If you wish to reduce your carbon footprint through solar power, you’ll want to know just how much solar energy you can get. These maps from the National Renewable Energy Laboratory (NREL) provide a great starting point.
You’ll notice two types of maps: photovoltaic (PV) and concentrating solar power (CSP). These are two different ways of generating electricity from the sun. PV panels use semiconductor materials to convert solar energy directly into electricity, and can be installed on a roof or in any open space. CSP uses an array of reflectors to focus a large area of sunlight onto a small central receiver, which then powers a heat engine (usually a steam turbine) to generate electricity. Because a CSP installation requires many acres of clear land, nearly all home and private installations are PV.
The PV map is color-coded, showing average kilowatt-hours per square meter of panel per day. Two major factors dictate a location’s solar potential: latitude and weather. The desert southwest (southern and sunny) has the nation’s greatest solar potential, peaking above 6.5 kWh/m2/day. This region is followed by the southeast (southern and cloudy), and then a band between the midwest and the interior northwest (northern and sunny). Next comes the northeast (northern and cloudy), and finally the Pacific northwest and Alaska (northern-er and cloudier), where a PV installation averages less than 4 kWh/m2/day.
NREL compiled these maps with data assuming a stationary PV panel oriented due south at an angle equal to the location’s latitude. Such an installation would point directly toward the sun twice a year, on the equinoxes at solar noon. Sun-tracking panels, which move to face the sun for all daylight hours, can increase the solar potential. (But sun-tracking panels are more expensive and take up more space.) More importantly, PV technology has improved since the maps were created in 2008-2012, so the values are conservative for a new installation today.
This Saturday, June 18, is Celebrate Solar Day in Vermont, with events statewide. Click here to find an event near you!