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Comment by AlexandrB | Hacker News Reader

> To put that in context: The total electricity consumption of the U.S. is about 4,000 TWh/year. The energy generated from 40 million acres of solar panels could theoretically meet U.S. electricity demand more than 13 times over.

How many batteries are required to make that generated electricity available at night?

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Depending on the the wind/nuclear mix in the grid possibly as low as zero.

But batteries are a very important innovation for power grids regardless of renewable energy goals. 50% of the job of an energy grid is just keeping the ac power supply stable when generation does exactly match consumption. Lithium batteries help smooth out spikes in demand over milliseconds and hours to save millions of dollars

Lithium grid scale storage is awesome no matter what happens with renewables.

Napkin maths would suggest something like 20% of a normal EV battery per household, so indeed a big investment, but perfectly reasonable. The harder part is that solar power production is much lower in the winter (depending on latitude), and seasonal battery storage is still a bit out of reach.

Zero. There are batteries that come in car shape and with wheels. People pay for them and there will be tens of millions, eventually 250m. They are mostly stationery (23+ hours/day) and are used 20 mins - 1 hour/day. They form a gigantic distributed storage reservoir, can absorb excess power (and get paid for it! energy prices go negative!) and supply power back to the grid when needed (and get paid again!).

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