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Comment by wmf | Hacker News Reader

For whatever reason, nobody is trying to build solar-powered AI datacenters. Maybe they can't find enough land.

The space required to install enough solar panels, especially in the places these things are going (like Ohio, where it's NOT ideal for solar generation), would far, far outsize the data center itself by a significant magnitude.

It takes 2.5 million solar panels to generate 1GW of electricity assuming 400W per panel and direct sunlight. 2.5M times 18 sq ft per panel is about 1000 acres or ~1.55 sq mi.

That would work for a 1 GW data center, during the day, without clouds, during the summer.

Is that supposed to be a lot? The US is some 3.8 million square miles.

A decade old Reddit thread estimated there are 60 square miles of just McDonalds. That is, a McDonalds footprint of solar panels alone is 39GW.

https://www.reddit.com/r/theydidthemath/comments/2bq7l2/so_i...

The US gov't owns at least 50% of every state in the west. Or they could just build in the middle of bum f*ck Texas and get fossil and renewables. Too bad Texas' grid is so piss poor

The Texas grid that already generates more TWh from renewables than any other state?

Half the time you get 0 solar power.

If only data centers had some kind of backup systems to prevent power interruptions, like inverters with batteries attached to them. They could call it an Uninterruptible Power Supply and then charge the batteries when other power is available and run on them when it isn't.

Not nearly big enough for data centers approaching 1 GW. Largest is 3 GWH which gets you 3ish hours.

Theoretically you can put as many batteries together but it'd be enormously expensive and run into the same supply chain issues.

Anything using 1GW of power is going to be "enormously expensive". The all-in cost of a 1GW data center is on the order of $50 billion. A billion dollars in storage batteries is ~2% of the cost, which is completely reasonable.

~1600 GWh of lithium batteries are produced each year and hundreds of GWh/year of production capacity have been added in each of the last few years, so ~12 GWh isn't going to upend the market.

UPSes are designed to run for minutes not hours. I guess enough Megapacks to run overnight would be more expensive than gas generators.

If grid storage batteries are economical in the general case then why wouldn't they be doubly so in a place where the inverters are a sunk cost and you're saving the transmission costs because the load is at the same site as the batteries?

The competition isn't the cost of generators, it's the cost of grid power, or the cost of operating gas generators every day.

They aren't economical in the general sense. They are economical to provide frequency stabilization, grid efficiency, and maybe a few hours of demand shifting. They're not yet economical to store solar power during the day and discharge it at night. We are getting closer but I don't think we are quite yet there.

As far as I can work out, the cost is competitive as long as you're using the capacity every day, especially when it lets you avoid paying transmission costs. The thing that doesn't work is to have enough battery storage to handle extended periods of low generation, because for that you need dramatically more storage capacity while only using the surplus on rare occasions. But a data center could use the grid or backup generators on those rare occasions while still using batteries overnight every night.

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