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Comment by nickik | Hacker News Reader

As for why nobody is building them. I would just point out that nobody is really building full solar with storage either.

That is starting but barley happening.

Utilities need to hit install some renewables and setting up some solar is easy. There likely is already a gas peaker somewhere so no need for storage.

I have not studied CSP in any detail so I can't say, but the reality is rational market actor in the current system does not optimize now for what the theoretical best solution is in 2040. They just need to hit their renewable quotas right now.

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Solar combined with “4 hours of battery backup” is 16+h of output.

Suppose you want 1GW of solar 24/7. Well 4h is roughly 1/2 the output of an array over a day. So to get 1GW during the day you need a 2GW solar array. Now your 4h batter is 4h x 2GW = 8GWh. Which means your 4h battery can provide 1GW for 8 hours a day combined with your 2GW array providing 1GW for another 8 hours, and less than 1GW for even longer.

Of course the grid doesn’t actually want X GW 24/7, demand is higher in the day and lower at night. On top of this 4h is sized based on maximum output, you need extra solar to cover cloudy days, but extra arrays also come with more grid storage. Thus at scale 4h battery backed solar arrays can roughly meet all of the grids energy needs.

Another factor is panels can be pointed slightly east or west if you want power earlier or later in the day. The tradeoff is less total output over the day, but with expensive storage and cheap PV it can be more profitable that way.

Why would anyone build solar with storage when the same amount of money is a much better investment for pure solar? There is no surplus of power during the day.

Storage to buy cheap energy and sell it back is also a completely separate enterprise. At the moment it looks like lithium iron phosphate batteries will work the best in the near future since they are the cheapest when taking into account the battery life time.

That's my whole point. We are not yet at a level of penetration where that is needed, so the problem solar concentrate plants solve isn't really solved yet in general.

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