One of the most important facets of renewable energy, solar energy stocks are companies that produce electricity by harnessing heat and light from the sun. This is accomplished by the use of solar technology including panels and similar solar architecture. The four types of solar energy are passive solar gain, solar thermal, passive solar power, and passive solar gain. Some of the industry’s most popular stocks are First Solar and Sunrun, two companies that have helped make solar energy production mainstream. Investors can also gain exposure through the Global X Solar ETF.