This is a known problem. It is also known to be exaggerated. The remedy is simple.

Let's say you are going to have 20% less generation on REALLY hot days over, say 35 degC. And 10% less generation at 30 degC and higher. Meh. Build 20% more generation capacity and forget about it. OR double your solar and get one more inverter and get a refrigeration unit for the inverters and you are done.

With EVs, the solution seems to be "make the battery bigger" and with coal generation plants, the solution is "let's make more, and not clean coal either, let's do it dirty." Solar is not a "finesse" thing. More is better. And it is cheap, and you already have the hardware, just bolt on some more panels and stop crying.  It just works. So build more. Way more. You need more? Build more. It is a no brainer.

And enjoy your greater capacity the rest of the year too.

I consider it to be a non-issue. Really. As a solar owner, it has never bothered me. I guess you want to factor it into your original plans, but people usually overbuild systems anyway.

So overbuilding is the easiest workaround. There are others.

Floating solar gets support for protecting water resources, but the water and shade also cool the backs of the panels somewhat.

I have heard of active systems that do not actually refrigerate the backs of panels, but, for instance, swimming pool heating coils can be set up behind solar panels to pull some heat from under the panels and use it for water heating.

I suppose, if this were a hugely important issue, spraying clean water on the panels would clean them and cool them at the same time. Seems extreme to me, but the hottest areas are also those with a lot of dust buildup on panels, probably, so why not clean and cool them at the same time?

dyhchong: I wonder if you could just run town water through them.

Every time you turn the cold tap on, water runs through. Water the garden? That water is first passing through the solar panels. Etc.

It's not like it matters if the cold water tap is dropping is 10'C or 30'C.

It gets so complicated that all of the costs get out of control and it just becomes more trouble than it is worth... BUT....

Here is a convoluted solution. You could have a 500 gallon tank of water or water mixed with antifreeze/pglycol and then run your mixture through some simple heat exchangers behind the panels. Then you can run a compression loop/heat pump to take the heat from that tank for use with your water heater, or for home heating. That would give you high efficiency for your heat pump, but separate your system from icky hot hoses on the roof. And then of course, the solar can run your pumps AND your heat pump.

So it gives you some "products" in the winter and summer, which are hot water and higher panel efficiency.

There is another wrinkle, which is that you could you could make the heat pump work in reverse, so that the solar panels would chill the water. You could run it to cool your panels AND your house in summer.

All eminently doable. All synergetically operated. Heat pumps and solar are a great pairing of technologies.

But as stated above, just get a few more panels and skip all the plumbing and fuss.

Personally, I find that, and although some farkers hate the phrase, "supply creates its own demand." Whenever you have a lot of some resource, which might be compost, trees, myoga, wood ash, garlic, and PV generated electricity, you start looking for ways to use it because SOOO many things become efficient or give you "comparative advantage" when you have a cheap and plentiful resource that most people do not have.

Solar PV goes GREAT with plug in hybrids, greenhouses, AC, heat pumps, refrigerators, freezers, etc.

There will come a day when AC will be used in greenhouses in summer to grow spring and autumn crops because it will be cheaper than shipping them from the Southern Hemisphere. People will hang out in greenhouses in winter to keep warm and in summer to keep cool.

Solar PV man. We are being distracted from it. It could turn the world upside down.