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Comment by dv_dt | Hacker News Reader

People often mixup performance of some component of the system, with total system performance, and system cost performance. Even this breakdown is probably oversimplifying.

I would suspect you're right on simpler being better here. That doesn't mean this isn't worth exploring. But one practical tradeoff calculation to make to see how viable this is right now is take the component cost of the cooling system and put that into more "simple" solar panels and see what trade of power generated is.

If that benefit isn't a win of the cooling system, then a lifetime reliability of the cooling system being less than a lifetime reliability of the solar electric components can only make that tradeoff even worse.

But making that calculation might still give someone a target for cost, performance specs to become a viable market option.

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Based on the numbers I have provided for the best days a day (of which I might get 50 a year) we can get 9% more output, but over a year that is maybe a few percent. If the pump needs replacing on typical pump periods of 5-10 years that will cost more than I would gain as each is going to be £200 (100 replacement and 100 for the pump) and that alone is more than a few percent of the system. If it drops the life of the panels to 20 years or requires one maintenance on the roof all the savings disappear instantly. Also if the panels cost more than 3% more than the electrical gains aren't worth it alone.

The problem is the gains are just too small and the risks and extra costs far too high.

Its not really fair because what you would do is flow this hot water into a water cylinder and get ~6KWh of water heating out of it a day. It will produce a lot more heat than that, you get nearly 4x as much heating as you do electricity but i can't use it, I don't need 120Kwh of heated water for showers and in the winter its not going to be enough to heat the house. That is fairly substantial amounts of extra power but I don't need that amount of panels of water heating I likely only need 1 solar heater, the rest is going to be wasted and not help in cooling the panels.

Who ever its for its not for people like me.

I wonder if it would be interesting for a hybrid pool heating & filtration system where you are already in for a cost of a pump.

The differential cost would be for an additional panel array loop and some isolation valves etc.

Solar pool heating is very much an established thing, and it does eat up a good chunk of a roof. So yea, if the quantity of hot water is an issue, that would certainly be a good place to dump it.

On the other hand, pool water has chemistry which may make it unsuitable for using in combined panels. Especially if it's a salt water pool, you don't want that water anywhere near electronics. The typical pool solar heating panels are basically just thin black plastic that the water flows through.

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