Is solar energy generated by light or heat? If there is basically no sun in the weather now, is light enough? Can I understand as long as it's daytime?

In theory, the working principle of solar energy is a device that directly converts light energy into electric energy through photoelectric effect or photochemical effect. When sunlight strikes a semiconductor, part of it is reflected by the surface and the rest is absorbed or transmitted by the semiconductor. Of course, some absorbed light becomes heat, while others collide with valence electrons that make up semiconductors, thus producing electron-hole pairs. In this way, light energy is converted into electric energy in the form of electron-hole pairs.

So you can use other light instead of sunlight.