Can you think of any other things that are important factors for using solar energy?

Demand and battery costs! If we want to use solar generated electricity when the sun isn't shining (like at night) we'll need to use storage technology (batteries) to capture excess energy for us to use when we need it. The only issue with battery technology is that it isn't cost-effective on a large scale for a long period of time, which means it isn't a good solution for the winter months.