There are 2 main technologies that are in use today for tapping into solar energy hitting the earth. The most common one is the photovoltaic or PV technology that converts light waves into electrical energy using special materials. The second type of solar technology is solar thermal, or concentrated, solar technology. This technology is primarily used for utility scale energy projects. It consists of thousands of giant parabolic mirrors installed in a circular pattern to concentrate the sun’s light into a heating area in the center of the circle located at a height. A molten salt-based fluid is generally heated where the sun’s light is focused which in turn is used to generate steam to run steam turbines. One of the big advantages of this molten salt-based solution is that it can maintain the heat for many hours after sunset to keep generating energy.
PV technology consists of individual solar cells arranged into rectangular solar panels to generate electricity. These panels are generally about 5 feet in length and 3 feet in width. There are various light sensitive materials that are used to make solar panels, depending on the application and budget. Silicon based panels are the most common and the cheapest panels available today. More expensive panels are sometimes used for utility solar projects and spacecraft to gain higher efficiency in a smaller area. Silicon panels typically have a commercial efficiency of 18-20% with panels in the lab reaching almost 25%. Just a few years back commercial efficiency was around 15%, so the industry is making rapid progress.
Some of the latest advances with PV include thin film technologies that use more expensive materials and perovskite technology that allows for flexible solar panels of thin sheets that can be applied on the outer structure of a building. These technologies are still not adopted at the same rate as silicon PV technology but are expected to make inroads commercially in the coming years.