Green Energy

Solar panels that absord heat exist, those panels are used to heat water. For PV you want to capture photons that kick electrons from the valence band into the conduction band of the material to get an electric current. Basically the inverse of an LED, you turn light directly into electricity. Any heat here is wasted energy. The PV cells are optimised for specific frequency bands and in those bands they don't reflect well. If you want to capture visible light the panels are appearing relatively dark.