like typically 77 deg F surface temperature. They may be running more like 120 deg surface temperature and they will produce less power with heat. The solar array on my house is rated as 4.2 KW but once warm produces more like 3.2 KW even though pointed pretty much directly at the sun. This matches the derating curves wrt heat. As the panels are turned away from the sun you will get a bit worse than a cosine function derating. In my installation, I didn't want to have them up on racks and have to turn them all the time, so it is a tradeoff.