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Comment by NortySpock | Hacker News Reader

'money spent on storage is mostly wasted, because to charge it up you would need to burn fossil fuels'

Huh? Why would you not charge your utility battery bank with surplus solar or wind power?

Bonus: at the point when solar or wind power would be curtailed (when it is generating more supply than the grid demands), is also when the wholesale price per MWh is zero or negative, making it free or profitable to charge your batteries.

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> Why would you not charge your utility battery bank with surplus solar or wind power?

Because you spent the money on more generating capacity, instead, and displaced exactly that much more carbon emission.

You put any excess power on a transmission line to someplace else that would otherwise be burning fossil fuel, and collect revenue. Maybe spend that on more generation.

If you are maxing out your transmission lines, spend money building those out. The more of those you have, the more places you can get revenue from.

When it starts to look like there will be nobody left to sell your excess to, then build storage.

This is already a reality on several grids across the world though. On weekend days with lots of sun and wind (ie low demand and high supply), prices dip below zero.

Just from an economic standpoint it can also be a valid choice to build storage next to unpredictable generating capacity, for example if you build a wind farm and want to sell during daytime (when prices are highest) as much as possible.

Those negative price stories have been around for years but the last time I checked, they still weren't because we had 100% renewables, which people assume to be the case. There's someone paying that negative price and it's generally fossil producers.

(Technically, a 100% renewable grid could go negative I'd there were separate subsidies, but as soon as renewable goes below that level it would just be shut off rather than pay money to generate.)

The point is that until all fossil fuel plants are shut down, when you have “excess power” that means you could either shut down FF plant or charge some batteries. If you choose the latter then the FF plant is effectively charging the battery.

That is better though for when the renewable plant isn’t running.

Yeah, I dont know if its pointless to get in early (as if now is really early) given the subsidies in some areas. And it does seem realistic to become an energy independent home for not that much investment which 10 year old me still cant believe is actually a reality.

But I do like the idea that these industries might actually be motivated to progress faster now if people hold off on getting on board. Seems like its enough of a reality that they can justify r&d to make the last push toward real competitiveness.

Then again my brains fried from work and I don't know what I'm talking about.

All I know is I want me some solar panels and an electric F150.

Domestic is a whole different domain from utility-scale.

The best thing for a house power bank is a used-up electric car.

At least here in Germany, at the grid scale, there isn't a real surplus of renewable energy most of the time, especially if you subtract all coal and gas power going into the grid. Of course on smaller scales, batteries make much more sense. For example, it is profitable to combine your private solar generation with a battery, as you don't get much by feeding your surplus generated power to the grid.

Also most utilities will not let you charge from grid. Its very hard to get interconnect agreement if a battery is involved

A distributed approach may solve many problems, enabling charging with surplus produced by renewables, and discharge when people are at work/home (<=> most of them not driving their electric cars): https://en.wikipedia.org/wiki/Vehicle-to-grid

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