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Solar Just Hit a Record Low Price in the U.S (earther.com)
456 points by toomuchtodo 11 days ago | hide | past | web | favorite | 339 comments





The true price of solar is the price to produce reliable, continuous energy. That requires something to smooth out the signal and store the energy, most probably a battery.

The solar + battery price is also going down, though not as fast as the solar only piece. But that's the metric we should be following. When that hits $30 per MWh, it'll be game over.


This comment gets made in every single solar article put on HN. The true price of solar is what the market is willing to pay for it. If the solar was ruining the grid or was way more expensive than what it seems, we would not keep seeing solar installed at this pace and at these costs.

We need to get out of the mindset that all power generators need to produce a steady amount of power 24/7. A flexible grid made of many power sources that can be ramped up and down can just as easily meet demand and may even be best since it is resilient when any one power source goes down for an extended period of time.

You can't just say that solar should be more expensive because it only works half the day. You could just as easily turn that argument around and say that nuclear and coal plants should be more expensive since they are only economical if run at a constant load and require long shutdowns every year for maintenance. There needs to be extra capacity on the grid to meet demand during nuclear/coal shutdowns, but no one states that nuclear and coal should be more expensive as a result.


You misunderstand the sense of "true" here.

The point is not that the "true" price in the sense of what it ought to be. It is the "true" price in the sense of what the market is actually paying for the service.

When people put out the number $23, they compare it with the cost of power and wonder why, if it is so much lower, it doesn't already swamp the current solution.

So the purpose of the comment is to explain that it is not a complete solution, and not reflective of the total ("true") bill.


I've thought about adding solar to my home and can't see any reason why I should even consider a battery for storage. I'm in Texas and so I get plenty of sun and my peak energy demand happens to coincide with that sunlight (due to HVAC).

Why should I worry about a complete solution?


Bob Bruninga has written and researched this a great deal. He's pretty well known and respected. He feels grid tie is the way to go for homes (no batteries). Lots of great info here:

http://www.aprs.org/off-grid-maybe.html

http://www.aprs.org/solar-now.html


The main reason I would consider a battery is for disaster recovery purposes. Being from the suburban NYC metro area, we've had multiple, multi-week power outages in the past decade.

We have a moderate sized portable generator, but running off that for weeks becomes a very unpleasant experience. Certainly far better than not having power, but unpleasant.

Driving 2 hours away to the nearest place we knew had unlimited fuel, turning my car into a rolling bomb on the trip back with dozens of gallons of fuel in gas cans, etc. And the endless droning of the thing running.

If those sorts of disasters are not a major concern for you, I don't think a battery makes much sense.


Do you have natural gas available?

You can also store quite a lot of propane in a small footprint without some of the issues that come with gas or diesel.


> we've had multiple, multi-week power outages in the past decade

That's a crass state, what causes these outages? Is it a investment backlog of the power grid?


Hurricanes and early in the year snow storms (trees fall down on power lines), cause these things to happen.

Might have something to do with being in a very dense area with some very old infrastructure.

It depends on how much your electric company will pay you for excess energy production. Currently you may get a good rate, but as more people install solar panels that rate is going to get worse, as it gets more expensive to deal with all the homes with solar. So figure out what the deal is in your location, don't get a battery until you need it. I Don't know, but I realize in the future if Austin Energy doesn't pay well for excess production I will.

You can also size your panels such that you never produce excess energy but you will be leaving a lot of roof space that could be making energy to waste. A sunny winter day still makes a ton of energy.


The sun goes down at night

And? I'm still connected to the grid.

I think you are talking about off-grid vs. grid, but the others are not. The cost of solar applies also to utility companies, and I think that’s what GP was alluding to.

The grid will switch to solar + battery if it becomes cheaper than alternatives (gas, coal, nuclear, etc.)


Unless battery/storage tech gets wildly better, you're still going to have to have the natural gas turbine plants that we're currently using for peak demand power to smooth out the inevitable spikes and troughs in supply from solar/wind renewables.

It's such a damned shame that so many decades of potential progress in nuclear power were stymied by misguided FUD.


You're replying to a comment about the true cost of solar being the battery + the panels, asking why anyone would think of buying a battery.

That's why.


That still doesn't answer their question. Why does the sun going down at night matter for people who are still tied to the grid?

If I move into a house with a grid connection only, I budget on power costs = cost of grid connection + grid power price.

If I move to a house with solar panels, I budget on power costs = cost of grid connection + X * grid power price + (1-X) * solar price (which is the capital cost of the panels smoothed out over their useful life).

The issue here is that I can't maneuver into a situation where my power price = solar price without sacrificing my ability to do anything after sundown without candles. Clearly, the true cost of power in a solar-enabled house is going to be higher than the cost of the solar panels.


Because you are also a taxpayer.

Huh? Are you talking about subsidies?

Not just that, also infrastructure investments.

Yet the market isn't "actually paying" for battery storage at anywhere near the amount of installed solar capacity...

Which was the point you misunderstood: dedicated storage installation are not needed at current production levels, and can be avoided even when solar's share of the energy mix grows.

Among the possibilities are "smart" appliances scheduling their demand to production peaks (dishwashers can often wait a few hours, cars might not need to charge right away). The same is true for industrial usage, where smelters, for example, have the natural capacity to store energy as heat.

A growing fleet of electric cars could also serve as distributed storage: if your car is parked for the night, it could feed energy back into the grid (partially, if you are paranoid).


You don't need 1:1 storage for solar production but it is a real problem. Germany and California are both facing the problem of the solar "duck curve", that is, high solar production during the day when demand is low and high electric usage at the end of the day when people get home from work as solar production is tailing off.

More than batteries they utilize gas peaker plants, inefficient, dirty and expensive plants that can ramp up and down quickly to match demand.


> You don't need 1:1 storage for solar production...

You seem to be referring exclusively to solar photovoltaic.

Solar thermal generation has quite a different, evening-friendly, distribution curve.


True, though the article was talking about PV.

I haven't followed closely recently but my impression was solar thermal has not delivered as promised. Things like Ivanpah was relying on natural gas more than expected. Is this an accurate impression?


> True, though the article was talking about PV.

Yet confusingly the article chose images of solar thermal. It's a bit of a worry when the journalists aren't conscious of the most basic aspects of the industry they are covering.


> True, though the article was talking about PV.

Perhaps, but we're better than conflating solar pvc with solar thermal - especially when we talk about large scale deployments, and even more especially when we talk about systems that incorporate Big Storage (batteries or otherwise).

Parent (to your comment) wasn't specifically PVC, parent (to them) wasn't either (more about true cost), and parent to them was bemoaning the common misunderstanding around how pricing works, rather than ethics / feasibility / ambiguity around underlying technology.

> I haven't followed closely recently but my impression was solar thermal has not delivered as promised. Things like Ivanpah was relying on natural gas more than expected. Is this an accurate impression?

My impression is that solar thermal is going to provide a much more scalable solution, especially in terms of avoiding the duck curve (or at least mitigating the impact of same). I see PVC + batteries being one of those tech combinations that works reasonably well in front of, as well as behind, the meter ... but solar thermal's definitely grid-level.


Ish, solar thermal has its own set of problems and limitations; they don't work during cloudy weather and the storing the thermal energy is tricky because you need a lot of high quality thermal mass

> Dirty

By coal standards?


>When people put out the number $23, they compare it with the cost of power and wonder why, if it is so much lower, it doesn't already swamp the current solution.

It is swamping the current solution - it just takes a while for new plants to be built and old plants to go offline.


However the amount of storage (battery or otherwise) for a network of renewable electricity producers depends on the full diversity of the complete network.

Which is to say, for example, that a grid supplied by solar and wind will need proportionally less storage per megawatt as the geographical size of the grid increases. A larger grid "averages out" the intermittent sources better as it gets bigger.


Not for solar. There are no grids nearly large enough to have half in the day time and half in the night time on average.

The type of renewable generator, ie solar, wind, hydroelectric, geothermal and tidal, or a combination thereof is another dimension of grid diversity.

You don't see it swamping thr competition for a bunch of reasons. You need capital in order to install solar, you also need to own your home and not be renting. A landlord has little incentive to install solar.

A state sized utility solar installation is non-trivial and that's why you don't yet see utilities providing solar themselves to the grid, and even if they did the price would be different.

So you don't see everyone using it because it's expensive to get started and because utility providers have yet to build solar plants capable of supplying a state. I don't think anyone has.

In time though, a combination of rooftop solar and utility scale battery/renewable systems to cover baseline load will probably be how we power the nation. Perhaps some gas or other generators will stick around to provide the baseline.


It is swamping the current solution.

Not only that. Solar energy production follows the sun, which incidentally is what humans also follow and when they are typically active and using most energy. Hence, solar producing energy when it is actually needed and in most demand (peak energy). This is even more so the case in hotter places that need AC.

Typically peak residential energy use is actually early morning and evening. And those tend to be the worst times for solar.

Solar is great for businesses and schools, well basically anything that operates mainly or totally during the day.


Residential-only energy use is irrelevant. What matters is peak grid usage (ie. residential+industrial) and it is actually mid-day—perfect for solar. For example the UK's real time grid monitoring system clearly shows this peak on the weekly chart: https://i.imgur.com/wTIt5tg.png (source: http://www.gridwatch.templar.co.uk/)

A weekly chart like that isn’t really granular enough to show that.

This chart is a few years old, but it shows that the peak demand was in the early evening:

https://www.eia.gov/todayinenergy/detail.php?id=830

The peak demand will also vary at different locations and times of year. As the wikipedia article states:

>...It depends on the demography, the economy, the weather, the climate, the season, the day of the week and other factors. For example, in industrialised regions of China or Germany, the peak demands mostly occur in day time, while solar photovoltaic system can help reduce it. However, in more service based economy such as Australia, the daily peak demands often occur in the late afternoon to early evening time (e.g. 4pm to 8pm).

https://en.wikipedia.org/wiki/Peak_demand


Your chart is even less granular than mine (hourly vs half-hourly), and it has a timezone conversion error. The source they use (ISO New England - https://www.iso-ne.com/isoexpress/) shows the peak of a typical October month to be between 3pm-4pm and not 6pm-7pm: https://i.imgur.com/5rWlnVO.png (the 3 hours difference is the timezone offset between east coast and west coast.)

My chart, if you look closely, has a granularity of one half hour. If you want something even more granular, ISO New England data more clearly shows the peak to be between 2pm-3pm for a typical summer month: https://i.imgur.com/rX1JqoJ.png


>Your chart is even less granular than mine (hourly vs half-hourly),

I think you might have posted the wrong image to imgur. You linked to: https://imgur.com/wTIt5tg

I am not sure how you are getting half hour indications on that weekly chart.

>...ISO New England data more clearly shows the peak to be between 2pm-3pm for a typical summer month:

Yes, that was why wikipedia says:

>...It depends on the demography, the economy, the weather, the climate, the season, the day of the week and other factors. For example, in industrialised regions of China or Germany, the peak demands mostly occur in day time, while solar photovoltaic system can help reduce it. However, in more service based economy such as Australia, the daily peak demands often occur in the late afternoon to early evening time (e.g. 4pm to 8pm).

https://en.wikipedia.org/wiki/Peak_demand

The EIA web site was talking about October, not the summer months when air conditioning would be used.

As another data point, With PG&E pricing, the most expensive hours are noon to six:

https://www.pge.com/en_US/business/rate-plans/rate-plans/tim...

I think my point is that statements like "hat matters is peak grid usage (ie. residential+industrial) and it is actually mid-day—perfect for solar." can over simplify the problem. The amount of demand will vary in different areas at different times of the year and even when it is raining, there will still be demand.


«I am not sure how you are getting half hour indications on that weekly chart.»

See https://i.myimg.io/wi9J.png

«The EIA web site was talking about October»

This is why I also showed an October chart, with a peak at 3-4pm.

But, yes, peak can vary with weather, time of year, etc. All I'm saying is that in general—not always—peak PV generation coincide reasonably with peak electricity demand.


>...See https://i.myimg.io/wi9J.png

OK, for many reasons we are just going to have to agree to disagree on that chart. (I just measured https://imgur.com/wTIt5tg and on my machine it definitely is more than 41 pixels between each day but that doesn't mean each pixel is representing exactly x minutes of time, there is no indication on the chart each pixel actually represents 35 minutes or if it is interpolated data, etc. To me it gives a rough showing of energy demand over a week.)

>...This is why I also showed an October chart, with a peak at 3-4pm.

It isn't clear to me why there would be peak demand at 3-4 in the afternoon in an October day. As the EIA site says:

>...During this period, usually in the early evening, operators need more generating capacity–including more costly "peaking" units. Both day-ahead and long-term forecasts account for these peaks to ensure the assignment of adequate capacity.

>...But, yes, peak can vary with weather, time of year, etc. All I'm saying is that in general—not always—peak PV generation coincide reasonably with peak electricity demand.

I think we basically agree on that. Peak PV generation is probably closer to noon, but in general more energy is needed during daylight hours than at night. (And obviously a hot sunny day will spike energy usage for cooling and solar PV is a perfect fit at that time.) The problem to me is when people over simplify this issue. The amount of demand will vary in different areas at different times of the year and even when it is raining, there will still be demand. I've always been a supporter of solar power but there is a lot of handwaving going on when people say we can get 100% of our power from solar and wind without there being some huge advances in energy storage.


Most energy consumption in the world is industrial, right? We wouldn't need to have nearly as many power plants (of any kind) if all those power plants needed to do was to sustain residential usage.

If you think of it as two power grids, then "the big power grid"—the industrial grid—can be fully powered by solar, and the residential grid, i.e. "the small power grid", is kind of trivial to solve in comparison.


Industrial power is often more amenable to demand shifting though. I want my kettle to start boiling now, but aluminum smelters don't really mind if the throughput is highest at 3pm instead of 3am or vice versa, especially if that gets them a cheaper price.

Even for domestic users, electric storage heaters, water heaters and electric car charging are all amenable to demand shifting. Over time, those will probably become the largest users of electricity if prices keep plunging.

I think there's a lot of money to be made out demand shifting tech, especially if people keep erroneously believing that variability is a problem best solved with expensive lithium ion batteries.


Not sure if it falls under "industrial" but commercial use (shopping centres, offices, etc) fits with solar brilliantly, and at least where I live, offices are rushing to get panels on their buildings. We had it quoted for our co-working space, and the pay-off time was 3-5 years, which is amazing.

Air Conditioners alone use about 6% of all electricity, so non-industrial is a big chunk: https://www.energy.gov/energysaver/home-cooling-systems/air-...

Unfortunately not the case, solar output peaks in the afternoon and load peaks in the evening. It's been termed the duck curve. https://en.wikipedia.org/wiki/Duck_curve

Where it's hot, people come home from work as the sun is setting, and turn on the A/C. It can be 85F overnight in many parts of the world, which makes sleep very difficult.

If you leave your AC running all day on solar energy ($0 marginal cost), do you still need to run it at night?

Yes. Our house in Australia is reasonably well insulated, but if I turn off the A/C, it feels warm again within about 15-30 minutes. During summer, it can remain 30C (86F) overnight, and higher than that well into the evening. Recently in Oman, the overnight minimum didn't drop below 42.6C (108F) overnight.

A "reasonably well" insulated house by Australian standards is still laughably poor compared to modern European standards. We build rubbish houses here, and we can't insulate worth a damn.

For ACs and cooking lunch, yes. For cooking dinner and artificial lighting, no.

Dinner is relevant. Lights… take a standard lightbulb form factor fill it with batteries and coat the outside with LEDs, and it can last most of the night.

Now you’re right back where this started - accounting for the cost of batteries.

Oh, and my stomach says dinner is most definitely not irrelevant.


It is an irrelevant portion of total electricity usage. It doesnt matter if a very small portion of your electricity usage has high costs.

Said batteries cost about the same as the LEDs, which — combined — cost less than the electricity they use in their working life.

How long can molten salt make steam after the sun goes down?

>If the solar was ruining the grid or was way more expensive than what it seems, we would not keep seeing solar installed at this pace and at these costs.

This completely ignores the fact that the people buying solar get subsidies and they aren't the ones paying for the burdened grid.

In some states, distribution companies are paying retail prices back to solar producers. That means these people get to freeride on the grid and force the power company to deal with their unstable power supply for free.


This completely ignores the fact that every form of power generation is heavily subsidized, one way or another. For example, in the USA "some states" heavily subsidize fossil fuels by not raising any tax on gas. Somewhat of a nitpicking point you are raising here..

The point of the article is that in this case, even without subsidies solar would beat anything else. This is despite heavy import duties that were recently imposed.


>heavily subsidize fossil fuels by not raising any tax on gas.

Unless they are taxing solar, that's not a subsidy when comparing the two.

Where fossil fuels are subsidized is in the externalities they don't pay for (i.e. environmental impact).


Highly polluting energy sources are not paying to clean up the environmental costs that they produce. Maybe THEY are the free riders.

From some externality to society perspective, sure. But that's definitely not true of a grid operation cost perspective.

A coal power plant does not get paid retail rates for the power it generates. The utility company charges more precisely to pay for transmission and the people to maintain it.


Ok, so what?

Let's punish the free riders and reward the people who are reducing the total societial cost of energy.

The fact that solar owners get access to the energy grid for free seems like a clever way to punish the free riders by increasing their costs in a roundabout way.

Don't want to pay the higher costs for your power grid? Then upgrade to cleaner energy! Sounds great.


You're punishing the wrong people, why is that difficult to understand?

The companies that operate grids are not the free riders. By having idiotic legislation that allows solar owners to free ride the grid, you only punished the utility company. Sometimes they own power plants, sometimes they don't.


I think you're looking at this only from an economical point of view and not factoring in environmental concerns.

In CA, though solar continues to be installed, we've reached a point--due to a lack of good/cheap storage ability--that at the end of the day (where Solar has been working fine all day), in order to meat evening demand, the only way to address steep demand is to fire up coal-fired plants. They work, but they're not only expensive, they're dirty.


> but no one states that nuclear and coal should be more expensive as a result.

Yes, yes we are.

The correct calculation uses the capacity factor, not the name-plate capacity.


False equivalence. A similar argument could be made of nuclear power (which needs to run at/near 100% output), or supercritical coal (similar operating constraint to nuclear). Do we need to add batteries to those as well to make an apples-apples comparison? (Incidentally, much of the pumped hydro in the US was built to integrate nuclear power).

Unless you're trying to power the grid with a single power plant (like on a small island), argument made above doesn't hold. The grid is a network of generators (and loads) with different operating characteristics.


Plus, just because the sun goes down doesn't mean all solar generating stations stop making electricity.

I'm not even remotely an expert in this field, but the towers at the solar furnaces I've seen continue to glow well into the night, meaning they're hot enough to still generate steam, and thus electricity, long after it's dark.

I don't expect they generate electricity all night, but maybe not as much energy needs to be stored as people assume.


the solar furnaces take time to heat up in the morning too, so its more of a skew of time, rather than a stretch of operating time, although depending on the efficiency, it may stretch too.

Not only that, but solar generated in one place can supply electricity to areas where the sun has not hit yet, and likewise after the sun goes down, those same places can draw power from further west.

I like the idea of having essentially a grid “wave”: in the morning your power comes from the East, in the evening it comes from the West.

From the article:

“Three years ago you almost never saw batteries as part of a new solar or wind project,” Naam said. “In 2018, we’ve seen battery storage frequently show up as part of these bids. Energy storage is becoming the new normal with solar bids.”

So they are already working on it with some of the projects at least, and there's no reason to think they won't scale up and start becoming competitive before too long.


I wouldn't bet on batteries, or at least conventional batteries, being the long term solution. There's interesting work being done with air pressure storage, flow batteries (the largest batteries currently under construction are mostly flow batteries in the 500MWh-1GWh range, though the technology is still in its infancy), and big scary vacuum flywheels.

All of these are far less developed than lithium ion cells, but have the potential to do a lot better on cost and longevity grounds.


Planet Money covered this recently: https://www.npr.org/templates/transcript/transcript.php?stor...

Here's an entry on the storage facility: https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...

"The biggest battery in the world is a giant lake tucked away in the Appalachian Mountains on the border between Virginia and West Virginia"

One of the more promising things is actually water-based storage using back-to-back reservoirs. Water has a lot of mass per volume and is really low tech. And it's a proven strategy that has been operational for many decades.


Pumped storage is great where the geography makes sense, but there are a limited number of good sites which can be economically connected where needed to grids. Long-term, I'd have more hope for currently emergent tech (flow batteries etc).

it is true that pumped storage and great solar locations are often in different locations.

maybe there is a possibility for retrofitting some existing dams that are used primarily as resevoirs and not power plants, since pumped-storage are net-neutral on resevoir storage.

example: https://en.wikipedia.org/wiki/Parker_Dam

...but i am NOT an expert by any means, and it's probably way more complicated than that.


I think the easy way to do this is simply to build extra generation capability on existing hydro dams, then letting the dams fill while the sun shines and the wind blows and empty out faster when they don't

It also introduces interesting financial arrangements. e.g. rather than profiting on the electricity directly, they make more money by selling options to sell at a fixed price at peak times.

As a child (25-30 years ago) I visited an hydroelectric plant in Wales. It always impressed me that such a simple technique could work so effectively. They also had a pumping system for use whenever say the nuclear plant had excess production..

One weird thought I had the other day: high voltage DC transmission lines are getting more popular. I wonder if it would be economical for a high voltage DC line to form a loop around the entire planet, so that the load can follow the sun through a complete cycle.

This has terrifying geopolitical implications, so probably no-one will want to depend on it anytime soon.

It's no different than data links, which have mostly worked without political interference.

In general, your data does not have value to me to steal it. Not so with power.

Data has plenty of value, and is often copied without authorization, but putting that aside, nobody would be stealing anyone's power. It gets produced in one region, used locally, and excess sold to the next region, where the same thing repeats. You already paid for the power entering your region so you can't steal it and you'll sell it on if it makes sense to do so. This is already how gas pipelines work for example. It's shit with gas because the flow is one way and shutting off the gas is often done for political reasons but with solar you'd have your own production ramping up a few hours later if the neighboring region either shuts it off or uses a higher percentage of what they produced. Either way the metering happens at regional boundaries so there's no stealing involved - both sides of the meter need to be in agreement before any power flows.

> Either way the metering happens at regional boundaries so there's no stealing involved - both sides of the meter need to be in agreement before any power flows.

Play that out a bit. Suppose you have a 500MW or 1000MW transmission line. It normally has a 1% loss. Today, you notice that it has 1.25% loss. Maybe someone's stealing power. What do you do? Shut off the transmission line entirely?


At the demarcation points is where power is measured. If you have losses you can tell which side they are on, and then that side can decide whether they are worth investigating or not.

They really haven't.

If only a different species had reached our level of intelligence first... This would be a cool solution.

In the US alone this would greatly aid a transition to wind and solar:

http://www.sciencemag.org/news/2016/01/better-power-lines-wo...


>In the US alone this would greatly aid a transition to wind and solar:

http://www.sciencemag.org/news/2016/01/better-power-lines-wo...

For all the talk about inventing new batteries, I wish improving the existing grid would be more prominent in the conversation. High-voltage longer-distance power markets are something that can be built right now.



Loss is still an issue

If the loss is less than about 75% in the worst case (i.e. 100 watts of generated electricity supplying 25 watts to the consumer), the benefits of optimal panel location combined with the lower cost of solar makes it better than or equivalent to current baseload power supplies like nuclear.

Batteries are pretty convenient though. They don't have any moving parts and can supply electricity on demand.

Not all lithium batteries are created equal in terms of longevity. A traditional lithium manganese battery might have 500 cycles in it before hitting 80% capacity. A lithium titanate [1] battery might be closer to 5000 cycles. A battery could be designed for long term usage and thus lower the long term cost, if not the upfront cost.

[1] https://en.wikipedia.org/wiki/Lithium%E2%80%93titanate_batte...


Another benefit is that if you can reliably get off grid, it reduces infrastructure costs at the community level. Say, for rural properties.

I think the key is that we can start to develop infrastructure just fine on lithium cells, and it might even accelerate the development of more efficient alternatives develop because it proves the market to investors.

The market of grid-level energy storage is already proven to investors and anyone in the utilities industry.

See CAES storage (Texas) and Pumped Hydro energy storage (https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...)


Some sort of battery based tech that is fairly unconstrained by site requirements, as well as complex construction engineering requirements seems to have much more potential.

The Bath County Pumped Hydro plant can give 3GW of power with over 10-hours of storage. That's 30GW-hrs. How many lithium ion batteries do you need to compare against that? "Small" Pumped Hydro Plants are hundreds of MW-hrs, and large ones are dozens of GW-hrs.

CAES in Texas was constructed inside of abandoned mine-shafts. Line the mine-shafts with steel to contain compressed air, and bam, cheap energy storage.

------------

The USA has lots of lakes and mineshafts. And electrical storage in one area can serve multiple states. Indeed, the Bath County Pumped Hydro plant contributes to the electrical stability of 16 or so states.

A $5 billion project here and there will serve more people and in a wider area. If the USA can take advantage of natural resources, in a sustainable way (it doesn't seem like Bath County's Reservoir is damaging the environment), then it should happen. We know how to make hydro-plants that are safe for Salmon and other wildlife (we need to ensure that future Hydro plants need salmon ladders for example), but as long as environmental concerns are identified and addressed, leveraging our natural resources is the most obvious way forward.


I didn't intend to discount the projects you mentioned, there are lots of approaches being pursued. The more of them get a real crack at the market the better in my opinion.

I think what ARES is doing has the biggest potential: running heavy trains on a closed loop uphill to store energy and downhill to generate. They claim 80% charge/discharge efficiency which is quite good. The technology is very well understood and mature and the environmental effects are lower than building a reservoir.

No more than the true-price of Nuclear is the price to spin-up and spin-down nuclear as the electric grid demands.

There's "baseload power" (coal, nuclear, wind, solar is really good for this), and there's "Peaker power" (natural gas and hydro are really good for this).

Hydro is super-simple. Just block the water if you don't need energy, and unblock it when you need energy. Ditto with Natural Gas, which can spin up / spin down arbitrarily.

Solar, Nuclear, and Wind generate power on their own schedule and can't really be bothered. But you use OTHER forms of energy when the sun stops shining.

Natural gas is expensive to run 100% of the time. But if you can run Natural gas only 20% of the time, then you're still saving money.


Agreed. Without some alternative form of energy in the morning and evening we may have already reached the saturation point of solar energy. See the Duck curve [1].

Once the heavily regulated energy market has time to adjust to market conditions you are going to see this energy surplus during the day being adjusted for. Where solar panels make economic sense today they may not tomorrow when energy prices for mid-day use plummet due to oversupply.

[1] https://en.wikipedia.org/wiki/Duck_curve


Energy prices plummeting in the middle of the day creates an enormous economic incentive for energy storage or demand shifting, which in turn makes energy in the middle of the day more valuable.

Thermal storage is super easy for cooling and can be used to shift the evening load.

Just offer economic incentives to put ac on a timer.


Prices will not plummet due to oversupply, they will increase as demand decreases to increase profitability. Electricity prices reflect only one thing: how high they can be while still being "affordable". Even now, in most major cities, residential pricing is 10x-50x of business/industrial pricing ...in the same zip code. The cost of production of electricity is almost enitely irrelevant to its' pricing.

What electric companies have rates like that? In the Midwest it is like a factor of 2 for energy, maybe (residential energy in urbanized areas around here is $0.10-$0.15 per kW-h, with a day charge of ~$0.50).

Why can't existing energy infrastructure handle the gaps? Does it take too long to boot up a natural gas plant just for the night?

Would still make a huge dent to energy needs and the existing infrastructure already in place.


Because total load on the power grid peaks at 8 PM when solar is providing nearly 0% of the power [1].

This means that no matter how many additional solar panels you add to the system, you are not displacing a single fossil fuel plant. Sure it's good that those plants are running nominally fewer hours per day per additional solar panel, but the cost to own, operate, and maintain the panels is roughly constant.

This results in the effect of increased prices for fossil power in a way that can't be offset by solar.

[1] https://en.wikipedia.org/wiki/Duck_curve


Industrial usage makes up a large percentage of total energy usage.

Industrial energy usage can be time shifted.

Who cares about residential power, if it is a small percentage of total energy usage?


That's what's generally happening. It's a bit of a limiting factor, though. As you have more and more renewable, you need more and more gas plants which mostly sit around doing nothing, which isn't free.

There's also the opposite problem, particularly in the case of wind turbines; if you have enough, then your base-load (ie coal, nuclear, hydro) plus renewable may sometimes exceed demand. This happens from time to time in Ireland, for instance, due to a large installed base of wind. At that point you have to turn off renewable, and that's not always trivial or instant. Storage would help there, too, by absorbing the excess.


> As you have more and more renewable, you need more and more gas plants

This is only true if the load on the grid is growing. In North America, it is not. Otherwise, you already have enough dispatchable generation available when the sun isn't shining or the wind isn't blowing.


This is assuming that you're replacing old, bad power (ie coal, or old-fashioned unresponsive gas plants) with a solar/responsive gas turbine combo. The US still has a fair bit of coal that could stand to be replaced, but I doubt there's enough gas to take up the slack of a solar/gas system without building more.

Over the past decade (since the wide-scale commercialization of fracking in the US), coal plants have been retired or repowered (with gas) at a record pace. I believe the share of generation has dropped from 50% to 30% in that period.

> This is only true if the load on the grid is growing. In North America, it is not.

The article I saw the other day showed growth of 4.5% (comparing Q1 2017 with Q1 2018)

Surely that growth in production is matched by a growth in load?

https://renewablesnow.com/news/wind-solar-farms-produce-10-o...


> Surely that growth in production is matched by a growth in load?

It is not, although consumption growth may trend upwards again as transportation is electrified (and oil consumption moves to electrical consumption).

https://www.bloomberg.com/view/articles/2018-03-01/americans...


The North American grids will need to start growing again, if electric vehicles become common.

That is true, and existing infrastructure does (mostly) handle the gaps.

How much does "existing infrastructure" charge to handle the gaps? This calculation differs wildly from as low as $6 to as high as $15, but I think $12 is the right answer.

So add $12 to solar only as a rough rule of thumb. Note that this $12 still comes with transmission issues, and environmental impact.


Without a buffer (like a battery) solar energy fluctuates highly because of clouds and other things that get in the way for split seconds during the day.

That seems like a point where distributed rooftop solar has a pretty good edge over utility solar (ie huge fields of solar cells). Spread over a large enough area all those tiny peaks and fluctuations will even out largely.

Also the cost of installation. At least for home solar, installation makes up the majority of the cost.

I have an idea for a product to solve this if anyone is interested in chatting. I just don’t have the capital or hardware knowledge to get it going.

Your username suggests an option, but I shall hope you are focused on solar at the moment

Solar is fusion, right?

Just solar but rethinking things into something you can start using without installing.

There's a local cooperative here in Germany (named Energiegewinner if you want to look them up) that acts as a facilitator for this. They're approaching this from all directions:

1. You can buy power from them at normal power company retail rates. You get power from the grid that they buy at wholesale rates, profits go into building out solar.

2. You can become a member by buying any number of shares. Capital gets used to fund solar buildout, profits go back to each shareholder. Each shareholder has one vote regardless of the number of shares they own to prevent buyouts.

3. You can rent them your roof space. You get paid, other people put cells on. You get reduced-rate power from your own roof's cells, excess goes to grid.

4. You can buy solar panels and rent them to the cooperative. For every large installation they make, they'll ask people to buy panels. You get paid a part of what the panels produce for 20 years, at a guaranteed rate, and at market rate after that.

5. You can have them act as a solar installer and set up panels on your property for your own use. They'll buy excess production and sell you grid power when you have insufficient production. In this case you finance the install yourself.

They have excellent economies of scale from standardizing installs and they allow people with capital but no roof space to connect with people with no capital but usable roof space. Because retail rates for power are high and they've centralized installation costs they're making an okay profit. Maybe something like this can work where you are?


Yes, and any estimate of solar only costs is composed largely of financing charges which is another way of saying capital costs. These include the installation.

Not entirely. About 10GW of solar capacity would cover the entire air conditioning load peak for California[1] That's when power prices are the highest, and it doesn't need energy storage. Pretty soon, most air conditioning load will be on solar power.

[1] http://www.caiso.com/TodaysOutlook/Pages/default.aspx


But you do need storage and/or backup providers because not having air-conditioning run on cloudy days is not an option.

Cloudy days are usually cooler, and you still generate solar power on those days.

True, you still need an alternative source of energy in those cases. But realistically, cloudy days reduces the sun, which usually leads to lower temperatures.

---------------

Personally, I think that cold-energy storage (aka: run air-conditioners on overdrive to chill water. Then use chilled-water to cool your house) is the ideal.

https://www.ice-energy.com/

It turns out that a vat of 480 Gallons of cold-water has a lot of cooling potential. Chill the water to 40F and you can cool down homes for hours using fans alone. With proper compressors and such, you are like 95%+ efficient.

Your failure mechanism is the probability that your vat of water begins to leak its cold air. Certainly a problem, but way simpler and less of a problem than explosive Li-Ion batteries.


Cold energy storage has always had the problem of utilization and capital cost. You need to buy the storage system and then that storage system may only be useful for 3-6 months of the year during 6 hours of the day. From a thermal efficiency perspective they're great but in general they get offed by the economics. For the price you'd end up gettinf better value off a battery storage system to do load shifting.

Ice storage seems uneconomical. But chilled water (40F / 5C) is reasonable.

If you see it from a total-cost-of-ownership, the chilled-water + air conditioning unit is overall cheaper than you'd expect. The air conditioner doesn't need to be rated for the peak-loads anymore, but can run more continuously at lower temperatures (ie: at night to store chilled energy into the water).

So you downsize your air conditioner, as you aim for average-loads... compared to everyone else who has to buy an air-conditioner sized for peak loads.

-------------

You seem correct about utilization. Now I wonder if a dual-use heat-pump / cooling system would be best. Heat up your house in the winter, cool down your house in the summer to double-duty the water-tank thermal energy storage.

-------------

The "Earthships" discussed elsewhere in this topic effectively use thermal energy storage in dirt itself to heat and/or cool the entire house. It seems to use a lot of land, but single-family home owners generally have a large-ish yard where the earth can serve as the energy storage mechanism.


Dealing with cold energy(coolth) storage whether it's in ice or chilled water is tricky mostly because of the capital cost involved with adding a storage system that can only do one thing, namely store cold. They're great for specific regions where you'll be using them on a daily basis. Chilling water outside of the peak times for use during peak cooling has been studied a lot in litterature there's a recent article here about storing excess solar energy in cooling energy:https://www.sciencedirect.com/science/article/pii/S221067071... , the main problem with the system is one of practicality. In order to effectively use the cold storage you need to use liquid cooling like the ones used in commercial buildings, that or switch to a water source chiller with a cooling tower. You can build it, but whether the total cost of that system is less than buying a bigger AC unit and paying more for power depends entirely on local conditions(seasonality,diurnal temperature changes, whether you pay for demand as well as power and whether you're on time of day metering).

------------ Using it for winter and summer does increase the utilization and would be best practice but places with winter/summer seasonality have a golden zone where you don't need active heating or cooling. If you're below 24c and above 18c you don't need much energy to maintain thermal comfort, provided you're not in a high humidity environment. During the winter it's better to use solar collectors with a thermal syphon for heat collection instead of stocking up heat since peak thermal demand occurs at night.

------------ They're known as earthpipes or earth hear exchangers and they come with their own problems, namely proximity to surface and thermal load imbalance over seasons. The earth is a really shitty thermal reservoir because it bleeds heat out the side and the top, the really big thing that it has going for it is that it's free. When you use the system in an environment thats either mostly hot or mostly cold you change the ground temperature in the long run, either increasing it or decreasing it over time. This in turn affects the ability of the system to condition air, there's also the problem that it can only bring the air temperature up to that of the ground during winter so you still need a heating system to supplement it; works great for cooling though. Basically the system gives you thermal energy at no operational cost(other than the fan) but you have to either accept whatever temperature it gives you or have a way to further condition it. Earthships generally use the sun in the winter to bring the temperature up during the day and have a thermal mass inside the house that maintains the temperature at night.


You realize the electrical grid means that excess power can go to other states right?

So... did you read the article, mr. top-voted comment?

> The Nevada auction also included a number of projects that link up utility-scale solar with batteries. Mastering solar plus storage will be critical for renewables to truly overtake fossil fuels, since they only generate power when it’s sunny or when the wind blows.

> “Three years ago you almost never saw batteries as part of a new solar or wind project,” Naam said. “In 2018, we’ve seen battery storage frequently show up as part of these bids. Energy storage is becoming the new normal with solar bids.”


There is an alternative. Don't "smooth" it out. Just provide double the capacity needed. If prices go low enough, you can solve the problem by just throwing more solar panels at it.

There's a lot of "lumpy" demand that peaks during the day, requiring no storage. E.g. all air conditioning would be perfect as a consumer of solar energy.

> reliable, continuous energy.

That's the job of the inverter, right? It uses free solar energy first and maintains reliability by supplementing it with costly grid power.


If you had actually read the article, you would have discovered that many of the projects covered in the Nevada auction included batteries.

How do you track it? What is it now?

To quote Dwight... "False."

It is true that a wide electrical grid needs a base load.

It is also true that solar isn't great at continuous power because of, you know, the Sun sometimes being behind the Earth.

But that doesn't mean you need necessarily need batteries. There are at least two scenarios where you don't:

1. You have an alternative to batteries for storage. This could mean using excess solar power to create some fuel that may well also be portable. This isn't an economic way of creating gasoline (yet) but in remote places this might not matter. It also might not matter if this power is essentially "free" (eg you need to build a certain capacity anyway which leaves times where excess power is being generated).

2. Power usage on electrical grids is also not smooth. It also peaks during the day when, as it happens, the Sun is also out. So your solar capacity is actually reducing your peak grid power requirements, which is incredibly useful.


With regards to #2: You should study the "duck curve" and "nessie curve".

In particular, in Solar-heavy situations, the peak energy is now 5pm. When the sun begins to set but there's still a large demand of electricity.

Batteries in today's form cannot solve the duck curve. So the only reasonable situation is to use natural gas plants to supply the grid with power. Future batteries need to be built more efficiently and cheaper to deal with the many Gigawatts and Gigawatt-hours (both power AND energy capabilities need to grow) to deal with the future duck curve and/or nessie curves.


I'm mostly gratified by what a "Dog bites man" story this is. Solar prices have been decreasing steadily for a long time so we should expect to see a story like this every few months until the adoption curve flattens out - which hopefully won't be for a while.

You'd think but photovlotaics have already been targeted as far as importing into the U.S., counterveiling and anti-dumping duties and what not.

They dodged this recent tariff change that took effect this week as 8541.40.60 tariffs currently aren't included in this tariff war with China but they could see more aggressive action.


The bit about storage becoming a routine part of bids was an interesting piece of information.

I was thinking the same thing. The gigafactory isn't mention in this, but could there be synergies with Tesla's (somewhat shady... pun intended) acquisition of SolarCity?

These sorts of installs aren't exactly the same thing, but maybe SolarCity needs to pivot to from distributed consumer to large scale utility.


Tesla has already deployed utility-scale storage in Australia and has contracts to build more for California utilities. Those are just the ones I know of.

Puerto Rico too.

Stock market hits all time high!!

Wonder if there is a bit of an Osbourne Effect limiting demand as potential buyers keep waiting to see if the next generation of panels are even better.

It doesn't seem to have slowed down TV sales.

TVs don't cost 10k. And they don't cost half as much every 5 years.


Oh yes, they do cost half as much in 5 years. I bough by 46" LCD 6 years ago for $1500, today you can buy a 55" for $600.

Slightly off topic... Interesting thing about solar in Utah (maybe everywhere? Not sure about the specifics): Utah gives every land owner pollution credits. They're allowed to pollute X units worth per year or something like that. Depending on certain criteria you're allotted a certain amount of credits. The problem is, these credits are transferable. So if I, for example, don't pollute, I can sell my credits off to someone who wants to pollute more than average.

Something (I think is shady) some companies are doing is selling solar for really cheap in dollars, but they subsidize the cost by selling it for credits. Average Joe is going to think he's polluting less, however since he sold off his pollution credits, his solar purchase has authorized someone else to pollute for him. Netting us nothing in the end.

(not an expert, so I may have misunderstandings and be oversimplifying things, but the point should be easy to understand)


I'm not familiar with Utah's program, but it sounds like an emissions trading / "cap and trade" program. https://en.wikipedia.org/wiki/Emissions_trading

There are two ways that this is netting something:

1. Utah gets to set the total allowable emissions/year. If this is set lower than what emissions would be, absent the program, then emissions will be reduced.

2. Companies have to pay for those credits. If the credit price ends up being high enough, then companies will invest in ways to reduce emissions, e.g. by purchasing carbon scrubbers.


It's not net zero impact to pollution, because polluters are forced to buy credits, which increases the costs of their pollution and incentivizes them to reduce it, while non-polluting technologies are subsidized by the income they can get from selling unused credits.

The key is how many total credits you allocate to begin with - they should be sufficiently scarce that large emitters need to buy credits - and continually ratcheting down the number of credits allocated annually.


> which increases the costs of their pollution and incentivizes them to reduce it

Or, they pass the cost to the very consumers that sold them the credits.


But that's fine, it'll increase the cost of whatever good is being produced and put pressure on the producers to reduce that price based on competitors polluting less making the same thing.

> since he sold off his pollution credits, his solar purchase has authorized someone else to pollute for him. Netting us nothing in the end.

You're forgetting the 'cap' part of cap-and-trade. The point is minimize the cost of reducing the total amount of greenhouse gas (or whatever) pollution across society. The reason for allowing people to sell their credits is that it reduces the economic cost of reducing pollution. It doesn't matter whether any given individual is polluting more or less, what matters is that total pollution is continually decreasing until we reach safe levels.


Thanks for the explanation. You're right. I wasn't aware of the full system. The parts I did know seemed like a shady loophole for bigger polluters to take advantage of.

Thanks!


Chances are the solar companies themselves are selling for cheap and taking credits as an "alternative currency", which makes sense for Average Joe as they no longer need them (in theory) as (I assume) excess credits have no value.

From there, the solar company probably covers their own pollution level and then sells the remainder of the credits at auction and capitalizes on the spread.

Company pollution rates will likely not be affected until it eats into their profits; rather, they will likely just buy credits up to the point where there's a breakeven between the cost of a credit and the savings for a credit. Whatever money is saved won't be used to increase pollution but rather just be reinvested into other parts of the company or released to shareholders.

In this case, the pollutant is paying money to pay less in taxation, the solar company is providing access to renewable energy, and Average Joe is going to be polluting less at home. I could get behind that.

EDIT: Also, this means that Utah could theoretically wean the state's pollution credits lower and lower each year until the cost of polluting is so high that pollutants either convert or leave.


I'd suspect that if the actual net is anywhere close to even, then that scheme having the side-effect of further building up the solar industry, is a massive long-term win for renewable energy and the environment.

That's a good point. I didn't really think of that. It still feels a bit off, but that does help return some of the feel-goods back into buying solar :)

The status quo in most places is : pretty much people pollute however they want at zero marginal cost to themselves, without needing any credits, and passing on the costs to the environment as a whole.

The credits are an improvement, because polluters at least have to pay for pollution credits, which means they have an incentive to pollute less.


Seems a bit unfair to single out land owners. One would think even non-landowers should have claim to the air.

I've never heard of this. What is the name of Utah's "pollution credit" program and where can I find out more? Google isn't helping me.


That does look like the right info. I think Utah has a typical emission credit program. Maybe xahrepap was overstating the case when (s)he suggested that every Utah land owner has emission credits they can sell. Emission credits seem to be limited to certain large businesses.

Not sure on all the details. Maybe it's only certain power companies. I know this did apply to a relative who was a home-owner in a city that generated it's own power, so maybe they have their own program different than normal. He was telling me about it when he looked into some of the fine print from solar salesman.

I understand your perspective now. Thanks. I'll study this more.

It netted us more solar power installed so that the next person will have it at a lower price through volume, encouraging cheaper s.p. for everyone else.

It sounds like a fantastic loophole that allows companies to break regulations. I love capitalism.

Then you haven't done enough research on cap and trade, which the vast majority of environmental studies show is an extremely effective way to manage the problem.

Effectively the same as moving manufacturing to 3rd world countries. Out of sight out of mind

As a person who's built PV systems: The problem of generating enough kWh in a month is solved. In pallet load and container load quantities, good quality PV panels are now very affordable. Roof and ground mounting systems, DC power wiring and interconnect systems are highly developed, modular and easy to build with relatively unskilled labor.

The problem to be solved now is economical, reliable, long-lasting (in number of cycles) battery storage. Or some other form of storage to draw those kWh back from when the sun is down.


Relevant bits:

> “On their face, they’re less than a third the price of building a new coal or natural gas power plant,” Ramez Naam, an energy expert and lecturer at Singularity University, told Earther in an email. “In fact, building these plants is cheaper than just operating an existing coal or natural gas plant.”

> There’s a 30 percent federal investment tax credit for solar projects that helps drive down the cost of this and other solar projects. But Naam said even if you take away that credit, “these bids, un-subsidized, are still cheaper than any new coal or gas plants, and possibly cheaper than operating existing plants.”

(emphasis mine)


>> Relevant bits:

>> “On their face, they’re less than a third the price of building a new coal or natural gas power plant,” Ramez Naam, an energy expert and lecturer at Singularity University, told Earther in an email. “In fact, building these plants is cheaper than just operating an existing coal or natural gas plant.”

>> There’s a 30 percent federal investment tax credit for solar projects that helps drive down the cost of this and other solar projects. But Naam said even if you take away that credit, “these bids, un-subsidized, are still cheaper than any new coal or gas plants, and possibly cheaper than operating existing plants.”

I'm assuming that's without factoring in the health cost externalities.


Yes, this is solely for cost of power. The healthcare savings and quality of life improvements are an additional bonus on top of very cheap power.

https://www.sciencenews.org/article/air-pollution-triggering... (Air pollution is triggering diabetes in 3.2 million people each year)

https://www.scientificamerican.com/article/the-other-reason-... (The Other Reason to Shift away from Coal: Air Pollution That Kills Thousands Every Year)


>It will operate at a flat rate of $23.76 per megawatt-hour over the course of a 25-year power purchasing agreement

Does anyone have data on typical wholesale power costs?


You can look up Locational Marginal Pricing (LMP) data. Some Independent System Operators publish the information online. It varies pretty widely by region, and by time of day, time of year, condition of the grid, etc.

ERCOT: http://www.ercot.com/content/cdr/contours/rtmLmpHg.html CAISO: http://www.caiso.com/PriceMap/Pages/default.aspx MISO: https://api.misoenergy.org/MISORTWD/lmpcontourmap.html


Various data here: https://www.eia.gov/electricity/wholesale/

From my brief browsing, $23.76 is <70% of the average $/MWh price across the available data.


That's mind boggling. This is absolutely incredible. Our country has so000 much hot, sunny unused land in the west. Let's cover it up with solar panels and make use of the free sunshine.

Storage and transmission are the ongoing problems here. Also applies to wind on the Great Plains.

that is about $2 cents on kwh! Sounds about right for wholesale price.

Interesting headlines from the "Presentation PDF" found at [1].

> Installed prices are higher for systems at tax-exempt customer sites than at for-profit commercial sites

> Residential new construction offers significant installed price advantages compared to retrofits

> No clear relationship between installer-level pricing and installer volume

> Prices vary considerably across installers

> Installed prices in the United States are higher than in other national PV markets

> Installed price declines have been partially offset by falling state and utility incentives

> Installed prices continued to fall in 2016, albeit at the slowest rate since 2009 [emphasis mine]

> Module-level power electronics have a seemingly small effect on installed prices

> Ground-mounted non-residential systems are generally higher priced than rooftop systems

[1] https://emp.lbl.gov/publications/tracking-sun-10-installed-p...


There is an interesting part about solar generating electricity when its sunny - it will help population move to warmer climes. If you live in Ohio heating in winter is a problem, solar isn't going to keep you warm on a cold night (ok batteries can help but they're expensive). If you live in the South West though its perfect as Winter nights dont require much heat and the biggest loads are AC at the times when there is lots of sun.

Perhaps this will mean living in Southern California, Arizona etc will be increasingly popular as energy costs will be much more affordable. Of course water is the next problem, but cheap electricity can help that too.


In my experience, the perception that "solar isn't for everybody", especially when using housing examples, is fooled by hidden assumptions that were made during the time.

Consider the situation in 1950 when you are building a house, you can double or triple the cost of home construction by insulating it so that the net energy needed to heat or cool it is minimal, or you throw a oil burner in the basement which is burning fuel oil that costs a few cents per gallon and keep everything nice and toasty. The "obvious" choice there was not to spend the money on insulation but instead to just use really cheap energy to manage the temperature range. Makes everything much easier to engineer.

If, on the other hand, you design with the assumption that energy is extremely expensive and so you minimize the need to use it to regulate temperatures within a house, you can design a house that is temperature stable with the minimal amount of energy input for air circulation.

That gets you houses in the New Mexico desert that need no air conditioning (air cooling) and churches and office buildings in the northeast that need no additional heating.

Things that I have read about include extended depth insulated exterior walls. "Smart" glass windows that reject 97% of the infrared and ultraviolet spectrum (I've got film on my house windows that are not that good but they do a tremendous job of minimizing heat load in the summer). Passive heat exchanger systems that keep the temperature balanced between upstairs and downstairs, and solar roof tiles that provide both insulation and energy for running the house.

Does that help you if you're living in a 'mid century wood frame house', probably not. But it isn't that solar couldn't meet the heating and cooling needs, it is that combined with good house engineering this is already a solved problem.


> That gets you houses in the New Mexico desert that need no air conditioning (air cooling) and churches and office buildings in the northeast that need no additional heating.

Do you have a source for your NM desert example? I'm doubtful you can keep a desert home cool with just airflow.


https://en.wikipedia.org/wiki/Earthship#Thermal_performance

I've visited a couple of these places, they are pretty neat.


It's a dream of mine to build an earthship-like house some day. But before that I would like to figure out how far I much I can cost-effectively retrofit my existing conventional house to be more passively heated and cooled.

I'm surprised that architects don't propose passive heating/cooling on new builds and major renovations. I guess clients typically don't demand it.


To my original comment on this, the economics are generally not visible to people. If you tell someone "We can build it one way and it will cost $200 sq/ft that will be energy efficient, or another way at $100 sq/ft that will require 25% more energy to keep warm/cool" and the person will make the false comparison of "wow it would cost 100% more to build and I would only get an improvement of 25% in my power costs?"

(those are all made up numbers but I have had the exact discussion with a builder when I added on a room and insisted it was at least as insulated as the rest of the house, the builder thought it a waste of money, I knew that I expected to have the room for 25 years or more and that the lower energy costs would be a net win.)


If you live in Ohio that is a problem, solar isn't going to keep you warm on a cold night

Houses built to the German Passivhaus standard would do just fine in Ohio. I used to live in Ohio and Western Pennsylvania, so I should know. There was one Minnesota church built with polystyrene panels that had to start running air conditioning in the middle of winter, the insulation was so good.

If you live in the South West though its perfect as Winter nights dont require much heat and the biggest loads are AC at the times when there is lots of sun.

It can get pretty darn cold at night in the desert southwest. Again, insulation is the key.

Of course water is the next problem, but cheap electricity can help that too.

It's 10X as expensive to use techniques like desalinization. It's so much more expensive, that lots of desal plants get built, then get mothballed because it's that much cheaper to get water by other means.


>Houses built to the German Passivhaus standard would do just fine in Ohio. I used to live in Ohio and Western Pennsylvania, so I should know. There was one Minnesota church built with polystyrene panels that had to start running air conditioning in the middle of winter, the insulation was so good.

You'd have to level most structures and rebuild from scratch to manage that in large parts of North America to make a difference.

Never mind the fact heaters aren't the only thing that use electricity at night.


You'd have to level most structures and rebuild from scratch to manage that in large parts of North America to make a difference.

New construction built like this is a good start.

heaters aren't the only thing that use electricity at night

Know your orders of magnitude. Resistive heating is just ridiculous. Heat exchangers are much better, but are like running Air Conditioners. In a passivhaus, my wife and I would be running a laptop, a clock, and the air filtration/exchanger, and that's it.

Heating water is one of the big energy users, but Solar Water preheat based on heat pipes even works a treat in cloudy, chilly old England.


The biggest challenge probably being the 2x4 walls... if there's one code change to future-proof today's new housing stock, it might be adding 2 inches to the walls, either with 2x6 studs or 2 inches of rigid foam, for R-20 or so. Much of the rest is possible to retrofit, though not always easy.

Actually, while we're on the subject, subslab insulation might be another.


It's a shame that there isn't the regulatory flexibility to subsidize desalination plants, because desalination plants are sort of like insurance policies in that you usually don't need them that much until a drought hits and then you really wish you had them.

That sort of long term risk averse thinking is exactly where the market economy needs to be supplemented.


The market economy would charge the almond cartel and alfalfa growers a lot more money for their water abuse in California, which would instantly eliminate the water problems for the entire state. Versus allowing $10 billion of agriculture industry to hold a multi trillion dollar economy hostage.

Let's add cannabis to the list which will use huge amount of water.

Which plants use a lot of water is irrelevant to the discussion. Unless illegal cannabis growers in California were somehow having their water subsidized, which I do believe to be parent's main point.

Would it make sense to combine California's ability to produce solar and need for water? Build solar plants that run during the day that power desalination plants that fill reservoirs in the western mountainous area which then releases the water at night downhill to the main canal system while turning turbines on it's journey?

is the expense of desalinization the electricity? Which would go down with adoption of solar?

This is a decade old, but I think that the proportions are still about right: https://desline.com/Geneva/Banat.pdf

See the slide "Cost composition for a typical seawater RO (reverse osmosis) plant"

Fixed charges (primarily capital cost): 31%

Energy: 26%

Maintenance and parts: 14%

Membrane replacement: 13%

Supervision and labor: 9%

Chemicals: 7%

Really cheap solar electricity could reduce the second largest expense (energy costs), but right now that's just an improvement for daylight hours. Battery-stored solar electricity is getting cheaper but it's not cheap enough to actually reduce nighttime desalination costs yet. And if you run the plant only during the day, you get less value out of the very largest expense (capital cost).


That's reverse osmosis. In a scenario where energy is very cheap (even if only for part of the day) there are other processes which require less maintenance, but more energy.

The previous slide in that presentation also shows a cost breakdown for a thermal process, multi-stage flash desalination.

Fixed charges (primarily capital cost) 42%

Energy 41%

Maintenance and parts 8%

Supervision and labor 7%

Chemicals 2%

Energy is nearly even with fixed costs for MSF, but fixed costs are even larger here. Leaving this type of plant idle between dusk and dawn would again raise per-unit costs a lot.


I imagine the idea is something more like one way to dump excessive solar capacity would be to desalinate water during the times of maximum power generation.

Or perhaps I just steelmanned the argument.


You also have to maintain equipment, but I think the electricity is the major thing.

> If you live in Ohio heating in winter is a problem, solar isn't going to keep you warm on a cold night.

(a) In any realistic scenarios where a grid goes mostly-solar, you'd expect that it would have adequate storage.

(b) Storage heaters are a thing (and far more economical than batteries).

(c) Modern "passive houses" and similar standards require surprisingly small energy input to heat, even when it's very cold outside. For whatever reason these mostly haven't been adopted in the US, but are becoming common in parts of Europe.


You could probably invest in a thermal mass hybrid HVAC system e.g. use solar during the day to heat or cool a large thermal mass (thick interior concrete wall/floor to whatever temperature you need it to be at night.

Actually maybe a well insulated house could be considered a "thermal battery". If you look at the CAISO reports, a significant chunk of the duck curve is related to heating/cooling. If you had a super well insulated house, you could do the heating/cooling during the day.

Instead today, people fire up the AC on overdrive when they get home in the evening to cool/heat the place down/up. What happens if your Nest could just fired it up at 3pm while the sun was still shining.

In fact the opposite is done today to take advantage of early morning peak pricing, commercial buildings cool/heat at 3am to get optimal energy pricing.

https://www.greentechmedia.com/articles/read/retired-cpuc-co...


Yes, this is a good idea, just expensive.

There are both passive and active options.

You need to drill pretty deep and have multiple wells, or have alot of land surface area and excavate (not too deep though).

Other option is using water from a well or spring and dumping that water back into another well or stream (with an increase in water temp.).


Aren't they using molten salt for this? I think I heard about molten salt being used in a few cases for energy storage. Too bad I can't recall the details. Have you heard about this?

Oh sure, I more meant at the consumer level. At the production level molten salt is used to smooth out energy production rates at concentrated solar arrays. My understanding is that concentrated solar is no longer able to compete with photovoltaic production in most geographies.

Why does it have to be electric heat? Natural Gas is doing a good job right now. Let's work on supplying electricity, for things that require electricity first. When we've moved away non renewable energy sources for electricity generation, then move onto the heating issues in colder climates.

But even with natural gas, don't you end up needing electricity to move the heat through the house?

Depends on the delivery mechanism. Our boiler (hot-water heat with radiators) has a pump that uses ~30 watts, and before we modernized our system it was entirely gravity-fed—hot water goes up to the living quarters, cold water comes back down to the basement. I haven't checked exactly, but I think our system uses around 100 watts total, and extracts 95% of the possible BTUs from the natural gas it consumes. The old system consumed basically nothing (just a bit to operate the thermostat controls), but was 80% efficient at best.

Not surprisingly, forced air blowers consume more electricity—100-500 watts, according to my quick Googling.


Very little, generally. The pumps on a water-based radiator system are typically tiny.

Yes Gas is great, but in 100 years it wont be cheap. I wasn't really talking about the next decade.

In a 100 years, at this rate there might not be any cold climates.

We've built oil pipelines, why not "electricity pipelines" made of refrigerated, super conducting cable?

High voltage direct current lines can already cover vast distances. Siemens has started supplying equipment for a Chinese HVDC project that will transmit 12 gigawatts over 3300 kilometers:

https://www.siemens.com/press/pool/de/pressemitteilungen/201...

That's a long enough line to stretch between California and East Coast states.

Getting rights-of-way for big interstate transmission projects is harder than actually building the projects after those rights are secured. Superconducting cables can carry more power per cross section than HVDC lines, but they're a lot more expensive and immature. Nobody has yet found a project that would justify full-scale superconducting lines over more conventional high voltage lines built with ordinary resistive conductors.


The technology that's being deployed right now for this is high-voltage DC:

https://pv-magazine-usa.com/2018/07/09/eia-examines-hvdc-for...

It's an infrastructure investment that would pay dividends, but requires getting through a quagmire of politics.


At 3% loss per 1000 km (625 miles) HVDC is already good enough I'd say.

We have a loooong way to go before cost of living in southern California is offsetting energy prices in Ohio.

My house faces south westish. I have a lot of roof on the back side that I think would be good for solar but all the automated online stuff seem to indicate it was be expensive and not pay off for a LONG while. At least around here in MN there's not a lot of residential push for it. Hopefully as prices drop it becomes more viable.

Solar is quite location (and latitude) dependent.

Duluth gets about half of the annual Global Horizontal Irradiance that Tuscon does, and that's before accounting for the fact that snow will sometimes cover the panels. In addition, Minnesota has significantly lower electricity prices than the big coastal states (partially due to the great wind resource in the SW corner of the state, partially due to political reasons).

There are other things you can do to make an impact in MN, though. An obvious one is roof and window insulation...


I've always wondered if it makes any sense (if you have the property) to setup a windmill instead of solar panels. I don't think there's much market in smaller / single home windmill installations and so the costs are probably much, much higher.

Small wind turbines are usually not terribly practical (noisy and highly visible), and also ineffective because of low hub height and wind shade in residential areas.

The multi MW giants that are erected these days on tall towers just make so much more sense.


There's some talk of combined solar/wind residential use.

Here's a video I found of a comparison of residential wind turbines, https://www.youtube.com/watch?v=opP13e-TvHM&t=1402s. This is a DIY resource, though.


I wondered the same. There are small windmills I've seen on cabins and such for intermittent use.

I’d get three quotes from solar installers [1] and have them include your 30% federal tax credit, state incentives, and any utility or SREC incentives. Your payback period is most likely less than 10 years, and your ROI on cash invested would be higher than the S&P500 [2]. Ensure you’re not paying more than $3/watt pre-incentives if you select a quote to proceed with.

[1] https://www.energysage.com/

[2] https://solarpowerrocks.com/infographics/solar-infographic-s...


Online calculators over-estimate costs for large systems. You can find newer installers who are more willing to negotiate prices, and play them off each other. I negotiated one company down from ~$3.5/W to $2.30/W (before 30% credit) on my large residential system - and these weren't budget panels either (Sunpower E20).

If you do the discounted cash flow calculation of solar, at $2.3/W, electricity costs you around 5c/kWh: http://databin.pudo.org/t/19ece6


I think your numbers are pretty optimistic. You're neglecting depreciation for one. Panels have a lifetime in the range of 20-30 years, inverters have a lifetime in the range of 10 years. 4% is also an optimistic interest rate for a loan that lasts the lifetime of the system. You may be able to get that for a ~5 year loan, but then you need to include the higher opportunity cost of the money that was used to pay that loan off which will be tied up for 20+ years.

Ok, I've updated the spreadsheet to properly account for discounted energy (discount rate: 4%) and degradation (at the rated 92%/25yr). It comes out to 6c/kWh, which is about 20% larger than my first number. Half of that increase was due to the degradation, the other half from the limited time horizon - and assuming the system will be worthless after 25yr (!!).

http://databin.pudo.org/t/4cb861

This is all just a thought experiment for me, because my electricity costs 22c/kWh :)


The cost of the system includes buying a new one in 30yr. I didn’t include deprecation of the panel, but modern panels such as Sunpower or Panasonic degrade at around 8% over 25 years, so maybe add a multiplier if 1/.92 to the cost to fudge that in.

As for the 4% interest rate, which in this case is really a time value of money discount rate, I’m comparing it to mortgage loan amounts (which is pretty much the average consumer's risk free rate of return). I’m assuming the buyer can afford a cash system.


I don't se how it includes the cost of a new system in 30 years. 2.3 * 30,000 = $69,000 and your cost listed is only ~$59k. 8% over 25 years is much better than I thought for the panels, but you still need to include about 10%/year depreciation on the inverters since you'll need to replace them every 10 years or so (at least that was about their lifetime last time I checked in Arizona, it may be different in cooler climates)

I'm including the 30% tax rebate and assuming solar panel installations will be 50% cheaper in 30 years which is pretty conservative given their price history.

Microinverters last 25 years.


Still not seeing $59k.

2.3 * 30.000 * 0.7 = $48,300 (30% tax credit)

2.3 * 30.000 * 0.5 = $34,500 (50% cheaper)

Total = $82,800

Regardless, adding up the cost of the second one in 30 years doesn't make sense for calculating kWh prices, depreciation and cost of capital are the only factors that matter and you are only including one of those.


Sure, looking at my spreadsheet I also discounted the cost by the same interest rate after 30 years, (1/1.04)^30.

Agreed that including the second system doesn't really make much sense, but I wanted a quick-and-dirty estimate without having to individually discount each year's production (as you would if you had a finite time horizon).


ROI for cash invested in your solar install is greater than 4% in almost every state.

I didn't say it wasn't. We're talking about the cost per kWh which depends on the interest rate that you can finance it with, not your ROI.

You should always be paying cash whenever possible for the remaining system cost (after incentives). Failing that, you should be able to get a HELOC, home equity loan, or roll the system cost into a first mortgage at low (~4%) fixed rates (that might also be tax advantaged).

Higher interest rates would change the equation, but I don't know of people who are using high interest loans (like an unsecured loan) to finance residential solar.


You have 30kW of panels? That's a large system. Most people cna't fit that many. The more panels you get the lower the price gets per kWh.

I have found it to be surprisingly proportional. I'm sure it gets slightly cheaper per kwh with large systems, but not by a lot. I had quotes around $2.5/watt for 9 kW systems and $2.5/watt for 15 kW systems.

Fair point since $2.5/W is over two thirds installation. If you buy the panels and install them yourself you'd save a lot of money.

Same situation as you. It does seem expensive, and my cost of energy in MO is really quite cheap.

I'm looking at DIY solutions. At least I can scale it as I have a few hundred at a time instead of trying to make $20k work in a budget.


This is truly good news, but is it really worth calling out that a record was broken when it's been trending down regularly over time?

It’s one of those rare feel good things that hasn’t been yet flooded by negative view points that often follow a wave of positive news... there is probably a name for this?

Measurable technological advancement?

See also Moore's law.


pre-backlash

The record being broken is just the headline of the article. The body is about the trend. The first sentence makes that perfectly clear.

Yes. Especially since it's a continuous trend of records.

It is still news when a wining team adds another victory to their streak and progresses towards the championship,

Also, as pointed out elsewhere, TFA was mostly about this good trend.

What point were you trying to make?


Key milestone awareness is important. The more people who know the raw economics, the better choices that can be made.

This isn't a key milestone though, pretty much every week it breaks this record. That said the more headlines we can get about renewable energy the better, the recent moves to prop up coal are super disappointing.

The article mentions that too.

It broke a record that was set [checks calendar] last week.

But I think the headline is being a little click-baity—the article's real strength is analysis. It discusses broader trends—for example that location is important here (Ohio isn't going to get these low bids because it just isn't sunny enough)—and is fun to read.


True, but calling out the milestone of beating operational cost of state of the art coal/gas plants is worth doing.

If you extrapolate the downward trend, it's very obvious that anything you build right now that burns fossil fuel is going to be a problem in terms of being able to compete throughout its projected life span. Prices are trending to the point where it will become economical to shut down existing and operational plants in favor of replacing them with solar or wind.

The next milestone will be when existing coal/gas plants will start getting decommissioned. This will start with the older ones but very soon after may be followed by the new and shiny ones Trump is trying to build right now. That is if he manages to get investors to back that at all. It would be kind of a dumb investment given the above.

And to preempt the battery comment, batteries were included with this bid, as is common these days.

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