Solar energy uses the light from the sun to produce power. Unlike fossil fuels, solar energy is available anywhere on earth. Solar energy is free, immune to rising energy prices, and can be used to provide heat, lighting, mechanical power, and electricity. Solar energy technologies include solar heating, solar photovoltaics, solar thermal electricity, among others, which can make considerable contributions to solving some of the most urgent energy problems the world now faces.

Solar Basics

Solar electric panels capture sunlight and convert it to clean power. Solar panels (often called modules) are made by combining many solar cells together. When solar panels are strung together in series and combined with other components, they become a solar electric system or solar array. A solar electric system can meet part or all of a home’s electricity needs.

Passive vs Active Solar

Broadly speaking, solar technologies can be characterized as either passive solar or active solar depending on the way they capture, convert, and distribute solar energy. Active solar techniques include the use of photovoltaic panels (solar panels) and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.

Discovery of Solar Energy

Solar electricity is the conversion of sunlight into electricity by certain materials that absorb photons of sunlight and release electrons. Electricity is produced when these electrons are captured. This phenomenon was first discovered in 1839, but the first photovoltaic module was not produced until 1954. Now, solar cells may power everything from calculators and remote highway signs to homes, commercial buildings, and large power plants. Solar cells power all satellites in space, making them responsible for the world’s communications products.

Capturing Solar

Power produced by a solar electric system is measured in watts (W). Solar panels are assigned a rating in watts based on the maximum power they can produce under ideal sun and temperature conditions. Consumers can use this rated output to estimate the number of panels needed to meet some or all of their electricity needs; however, the exact amount of energy produced by a solar electric system also depends on roof orientation and tilt, as well as other factors such as shading, dust, and system efficiency.