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Comment by bryanlarsen | Hacker News Reader

Note that this is the raw number, it doesn't account for the low capacity factor of wind and solar. In other word it doesn't account for the fact that solar doesn't produce power at night, etc. So it might not be 25% of the energy produced. Although it'll probably get close -- the capacity factor of other sources is well below 100% and dropping quickly because of competition from cheaper sources like wind & solar. For example, the capacity factor of coal plants in the US is only 60%, not much better than wind's.

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Wrong, it actually DOES include capacity factor, "generation." Solar is around 5% of generation (i.e. kWhs of energy produced in a given year) if you include behind-the-meter[0]. Wind is at 10% [1].

Solar is growing at about 25% year on year, and the "Inflation Reduction Act" should help sustain this. So after around 3 years, solar will be about 10%. Wind is growing slower, but 15% of electricity from wind in 3 years is feasible.

Did you actually check first?

[0] https://www.eia.gov/electricity/monthly/epm_table_grapher.ph... [1] https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...

The article and OP were talking about available generating capacity as measured in Watts not Watt-hours. The capacity factor is absolutely necessary if you want to extrapolate that over time.

Please double check the reported solar capacity (the article) vs the reported power generation (your links).

The report shows 84GW of current solar capacity which, multiplied by the hours in a year gets you 735,840 GWhr if running at peak all year.

Your links shows a total of 204,110 GWhrs solar generated in the year of 2022. So the very information you shared confirms a solar capacity factor of roughly 28%. The sun doesn't always shine and solar panels don't always run at peak. This is common sense, but the article makes no reference to it.

The day/night performance of Solar is pretty interesting in the South, where solar's cycle nicely correlates with air-conditioning.

Even outside of air conditioning, generally the demand is higher during the day than during the night. It's often off by one hour or so though as there is often a peak in the evening.

In Texas they're currently seeing some solar plants producing above nameplate capacity exactly at the time when air conditioning demand is at record levels.

There's a simple technology called a battery that is being produced at twh scale per year now that addresses this. On sunny days, charge the batteries from sunrise until sunset. And then people can cook, run the AC, etc. Fairly easy problem to solve. Charge during the day, cool at night. Battery prices keep on getting more and more attractive.

Solar in the US is easy. Most of the US is south of most of Europe. If people in Germany at 52.5 (Berlin) degrees latitude can economically use solar, it should be no issue whatsoever for people at 40.7 degrees latitude (New York). Not to mention those lucky people blessed with long, warm sunny winter days at 25 degrees latitude (Miami), 29.7 (Houston) or 37 degrees latitude (San Francisco). Plenty of light there all year round. Most of the US actually matches Northern Africa in terms of latitude. Marakesh for example would be at 31 degrees latitude. That means a relatively stable and longish amount of time between sunrise and sun set. About 9 hours of daylight in New York around Christmas. More for anything south of there. Texas should be more than fine. There's a reason temperatures are so toasty there in the summer. It's at the same latitude as the Sahara desert. Plenty of light in other words.

For most of the US, solar should be usable throughout the year. It being cold doesn't mean it's dark. Also, solar panels actually work better when they are cool. So cold temperatures and sunny days are a good combination. Clouds are more of an issue, of course. But they are more of a local thing and they you don't have those every day. And even they let through some light. If you have to wear sun glasses to protect your eyes when you go skiing, it's an excellent day to be generating solar power as well.

We also have new battery technologies (suitable for grid style storage).

Such as Vanadium Redox flow batteries;

There was a big push for local salt reactors for cities or neighborhoods, but Vanadium Redox flow batteries could be a local solution to level demand from Solar/Wind -- or more simply, to balance load during the day; ie run ACs off of liquid batteries that charged last night.

More simply, there are thermal storage technologies that address it. Just precooling a building below the desired temperature at the peak, for example. Or, make ice. A cube of ice a meter on a side would be quite adequate for a single family dwelling.

It would help if Texas buildings had better insulation. The more insulated, the less quickly they heat up when the A/C is turned off/down, and the less storage needed.

That's actually a good question. Assuming need for energy storage, what would be more efficient? An insulated heat-capacitor (eg: a bunch of pans full of ice) inside the AC to be used when energy is in short supply, or a battery?

I think cost of the storage system would be more important than the efficiency.

Winter is not only worse for solar because the sun is less intense, but also because its cloudier.

variable pricing (within reason) will quietly solve all kinds of problems organically.

At 45 degrees north solar also nicely correlates with air conditioning needs.

it does not cycle well with heat in the North though.

It will also be interesting to follow how the development of solar and wind power will affect the stability of the electricity grid and the ability to prevent large fluctuations in frequency.

> solar doesn't produce power at night

I've always wondered, if we had a huge solar farm in a nevada or arizona desert, could we have a satellite with a mirror lens to redirect sun from above the horizon down to the panels so they can generate power throughout the night as well?

If you have the ability to put that many mirrors in space then you could just put the solar panels in space and beam the energy down to Earth as microwaves like this.

https://www.space.com/space-solar-power-satellite-beams-ener...

Aside from other issues mentioned, I think a lot of people would object to that sort of light pollution.

And if we are concerned about the damage to desert ecosystems that covering them with solar panels would cause, consider what the damage would be to an area that is now suddenly perpetually bathed in daylight, even at night.

That’s a very interesting concept. Even completely putting solar aside. Im just imagining a cluster of satellites redirecting light at will to make it daytime whenever we want.

Sounds like hell on Earth

Why do people keep writing comments like this as if utility scale batteries don’t exist?

Because they don't at close to the necessary scale. This site shows a projected July load profile for ERCOT (Texas) in 2035:

https://www.spglobal.com/marketintelligence/en/news-insights...

Note that Storage contributes for about four hours and at its peak comprises less than 7% of the total load serving capacity in the state.

I'm not saying batteries don't exist and aren't useful, but the scale is very small at the moment. Too small to be a comprehensive way to balance out the low load factors of Wind and solar. (Which are also a useful but incomplete component of the overall electrical portfolio.)

Going by that projection, they should build a lot more solar and wind rather than worry about batteries.

It costs somewhere around $300/kwh to build utility-scale storage. Say they can cycle 3000 times. We find that just the storage costs $0.10/kwh, which is in the range of generation costs themselves (probably double wholesale generation costs). So one cannot assume to be able to cheaply store power in utility-scale batteries.

That 3000 number is 0 - 100 - 0 cycles. You can get almost an order of magnitude more by using the sweet spot of the battery: 20 - 80 - 20 for standard nickel Li-ion batteries, and 30-100-30 for LiFePO4 batteries.

Is that an order of magnitude of cycles or energy throughput?

Cycles. Li-ion goes from ~600 -> ~3000, LiFePO4 from ~2000 -> ~9000. So "order of magnitude" is a bit of an exaggeration, and the 5x reduces to 3x when you use energy instead of cycles. But 3x is still pretty significant...

If storage costs are the same as generation costs, you’re just saying that storage is currently cost effective. Sounds like we should build a lot of it!

They exist and are finite in cycles.

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