Page - 106 - in Water, Energy, and Environment - A Primer

100 GW/year has been achieved. It is anticipated that annual installations will easily exceed the 100 GWmilestone through at least 2022. In the US solar energy (PV+CSP) has ranked first or second in new electric capacity additions in each of the past 5 years, and its increasing competitiveness against other technologies has allowed it to quickly increase its share of total USelectricalgenerationfrom0.1%in2010tonearly2%in2017. Solar cells are made from a variety of materials for a number of uses, ranging from terrestrial to space applications. First-generation cells were made of monocrystalline and polycrystalline silicon. Such devices today achieve conversion efficiencies (sunlight to electricity) of about 20%, while specialized cells designed for use at high solar concentration levels can achieve40%ormore. Second-generation cells utilize thin-film technology, which reducesmaterial demand and facilitates large-scalemanufacture. Examples are cells made from amorphous silicon, cadmium telluride, and copper indium gallium diselenide. Their efficiencies are approaching those of monocrystalline silicon. Third-generation cells include a number of thin-film technologies that are in active, pre-commercial development; manyuseorganometallic compoundsor inorganicmaterials. In general PV is a transformative technology that changes the way we generate and use electricity. It can be used wherever the sun is shining, e.g., in space to power satellites and space stations, in remote areas on Earth, and even on Mars to power robotic vehicles. It can generate power where it is needed without the need for power lines, it is modular and easily and quickly scaled up, and its cost is coming down dramatically as more and more PV is manufactured and deployed. Our infrastructure is already highly dependent on PV – think about satellites used for wireless telephone communication and GPS, and terrestrial PV that increasingly is supplying electricity to utilities as well as individual homes and businesses. Water,Energy, andEnvironment–APrimer106