No need for solar panels that get torn off with the first tornado, you can employ the very heat that tries to turn your house into a sauna. For everyone I know with an older house, you just can't get the upstairs cool without icicles in the basement.
I'm getting my roof redone with the full enchilada of a competent company (Walker). It's costing a mint because the house is a dog's breakfast of extensions. Even now they are having trouble with huge amount of siding that has to be removed for new flashing. But the best thing is that they upgraded the venting.
I got these huge things now, but you can't see them from the street. I call them my 'belfries'. They have a chimney effect, but the most the important is installing soffit vents on the old part of the house. This can be done by removing the plywood and installing the vents from the top. It makes the house so much cooler. The physics is excellent because the soffit vents lay down a layer of cool air, and this draws out air from the top with a powerful chimney effect. Much better physics than squeaky whirly things and all those useless small vents you see everywhere. They close up all those small vents, so the physics works.
The convection of hot air is a powerful force that saves our world from all the silly things like 'greenhouse effect'. I've never seen the cheap roofers in the neighbourhood change the venting. Do this and be happy.
ps. with the flat roof, it's amazing how the old roofer didn't have a clue. It wasn't attached at all, and the membrane just held down by weight. Still, it did last over 20 years. Amazing what you find when get somebody competent.