While solar panels generate electricity when exposed to sunlight, they do not have any means of storing this energy. And it is precisely this ability to "store the sun" that is making storage a valuable ally for those seeking energy. Even the most ardent solar evangelists can agree on one limitation solar panels have: they only produce electricity when the sun is shining. But, peak energy use tends to come in the evenings, coinciding with decreased solar generation and causing a supply and demand issue. The thing is, solar. The technology behind solar panels has evolved significantly over the years. Solar panels are made up of photovoltaic (PV) cells designed to capture sunlight and transform it into usable electrical energy.