Solar power is generated when photons from sunlight strike semiconductor cells and knock electrons free, creating direct current. Panel output depends on cell material, bandgap energy, sun exposure, and inverter type. Solar photovoltaic (PV) power generation is the process of converting energy from the sun into electricity using solar panels. Solar panels, also called PV panels, are combined into arrays in a PV system. PV systems can also be installed in grid-connected or off-grid (stand-alone) configurations. The sun's core is a whopping 27 million degrees Fahrenheit. This extreme temperature and pressure causes hydrogen atoms to collide and fuse, creating helium. There are two main types of solar energy technologies: photovoltaics.