Photovoltaics and Solar Radiation

Solar and wind will power the bulk of a 100 percent WWS all-sector energy system worldwide. The main types of solar generators are photovoltaics for electricity; concentrated solar power for electricity and heat, and solar thermal systems for heat. The sun produces enough energy annually to power the world for all energy purposes with PV alone about 2,200 times over in 2050 if all energy sectors were electrified. Over land, PV could provide about 620 times the energy needed. Needless to say, the world needs to capture only a small portion of the sun’s available energy. For example, only 0.08 percent of all sunlight hitting Earth annually is needed to provide half of the world’s all-purpose energy from PV. Given the large potential of PV to power all energy needs, it is useful to understand PV panels and solar resources better. This chapter discusses both. The chapter starts with a history of solar photovoltaic cells, followed by a description of how modern cells work. It then discusses PV cell efficiencies, PV panels, and PV arrays. Lastly, it discusses solar resource availability and optimal tilt angles for solar panels.