We all know the sun warms us, gives us light, makes plants grow, and is an important source of electricity.
But does the sun’s light make electricity, or is it the sun’s heat?
The answer is both. Different technologies capture light or heat to generate power. It may be done on a large or small scale. That means homeowners, small businesses and power companies that run utility-scale solar farms all can rely on the sun if they have the right tools.
Here’s a look at the different kinds of sun power and how they are used.
Passive versus active solar energy
The sun’s power may be tapped for energy passively by locating buildings to make the most use of the sun. Good sun exposure, construction materials that capture the sun’s heat, windows that maximize sunlight, and built-in natural air circulation all take advantage of the physical surroundings.
Active solar power involves more machinery or technology to make sunlight into electricity. Some use the sun’s light and others use the sun’s heat.
Solar panels use the sun’s light
Solar panels use sophisticated technologies to convert sunlight directly into electricity. They’re technically called photovoltaic cells or PV. Solar panels are versatile, because they can be used on individual houses and commercial buildings as well as on large solar farms.
Solar panels can provide electricity to off-grid sites or feed electricity into the general power grid. A small solar panel can supply enough energy to power a few lights or a laptop in a place not connected to a power grid.
Electricity generated by rooftop solar panels can deliver power even after the sun goes down, if energy-storage batteries are used. Where power grids are equipped to accept it, excess electricity can be a moneymaker for small producers using distributed energy resources like solar.
Some sports arenas generate enough electricity from solar to power hundreds of homes in nearby neighborhoods.
A huge solar farm can power entire towns. Among the largest such projects are the Topaz and Solar Star plants in California, both run by MidAmerican Solar.
Mirrors use solar heat
Other technologies use mirrors or lenses to concentrate the energy from the sun to other devices, such as engines or steam turbines, which then create electricity. That’s called concentrating solar power, or CSP.
Here’s how it works. Thousands of mirrors concentrate beams of solar heat on towers that heat boilers. The heat produces steam that runs turbines generating electricity.
The SolarReserve Crescent Dunes plant in Tonopah, Nevada, is the first to commercially use molten salt as a way to store solar energy for later use. Molten salt storage can extend the availability of solar energy to customers as long as 12 hours, meaning overnight.