We have a small 15m by 15m garden here in Kuwait (we have a similar climate to Egypt if not a little more hot). To keep planting all year long, we run a “protect from insects” fine mesh over the entire garden and it feels significantly cooler while still allowing sunlight through. Not scientific enough, but we never thought to check the temperature drop or the sunlight reduction. I may do that this summer just to see how much light is blocked.
Plants don't use most of the sunlight that hits them, and too much will cause heat stress making them less efficient.
The right tarp or net that lets through the most useful wavelengths seems to help more than hurt.
A lot of places are starting to install solar over farm installations on a small scale. Yields are tending up while also generating electricity to run the operation
You still need more than you'd expect. Plants need CO2 to live, and with CO2 at just 0.04% of atmospheric air, you need to let a lot of air (and accompanying water vapour) in and out of your greenhouse to let the plants have the CO2 they need.
Or you burn natural gas to produce CO2 (and some water), but then your carbon sequestration goals go up in smoke...
