All life on earth is supported by the sun. This amazing resource radiates energy and provides us both heat and light by fusing hydrogen into helium at its core. We call this solar radiation. Only about half of this solar radiation makes it to the Earth’s surface. The rest is either absorbed or reflected by clouds and the atmosphere. Still, we receive enough power from the sun to meet the power demands of all mankind — millions of times over. Solar energy—power from the sun—is a vast, inexhaustible, and clean resource.
Sunlight, or solar energy, can be used directly for heating and lighting homes and businesses, for generating electricity, and for hot water heating, solar cooling, and a variety of other commercial and industrial uses. Most critical, given the growing concern over climate change, is the fact that solar electricity generation represents a clean alternative to electricity from fossil fuels, with no air and water pollution, no global warming pollution, no risks of electricity price spikes, and no threats to our public health.
The solar resource is enormous. According to the US Department of Energy, the amount of sunlight that strikes the earth’s surface in an hour and a half is enough to handle the entire world’s energy consumption for a full year. Just 18 days of sunshine on Earth contains the same amount of energy as is stored in all of the planet’s reserves of coal, oil, and natural gas.
And, once a system is in place to harness the solar resource and convert it into useful energy, the fuel is free.
Since 2008, U.S. installations have grown seventeen-fold from 1.2 gigawatts (GW) to an estimated 30 GW today, enough to power the equivalent of 5.7 million average American homes. Since 2010, the average cost of solar PV panels has dropped more than 60% and the cost of a solar electric system has dropped by about 50%. Solar electricity is now considered to be economically competitive with conventional energy sources in several states, including California, Hawaii, Texas, and Minnesota.