June 20 (6:34pm ET) marks the summer solstice, which is the first day of astronomical summer. This is the day in which the most sunlight reaches the northern hemisphere, and when the sun is highest in the sky at noon. As a result, it is the day when the amount of incoming solar energy is also the highest.
However, the amount of solar energy reaching the ground depends on latitude and atmospheric conditions. Consequently, not all ground locations receive their maximum amount of solar energy on the first day of astronomical summer.
Locations with cloudier climates have a lower potential for electric generation during all times of the year, an important consideration when calculating how much electricity can be generated from solar panels.
Using a tool from the Department of Energy's National Renewable Energy Lab, we examined the solar energy potential in your market. The tool takes into account climatological conditions and allows the user to specify how solar panels are installed at their home or business. The web tool can examine the potential of solar panels installed in a zip code region and provide information on the value of the electricity generated by solar panels.
A modestly-sized solar panel installation facing south on the roof of a single family home in most parts of country can generate 400-500 kilowatt-hours (kWh) of energy during each summer month. In sunnier climates like Phoenix, the number can approach 700 kWh. Even in the winter, northern climates can produce 300 kWh per month, and cloudier climates can also see benefits.
A kilowatt-hour is 1000 watt-hours, the amount of electricity required to power a 100-watt light bulb for 10 hours. A few other examples of electricity consumed by appliances operating for one hour are below:
Desktop PC: 0.075 kWh
40” Television: 0.234 kWh
Dishwasher: 0.330 kWh
Clothes Dryer: 2.79 kWh
Water Heater: 4.50 kWh
While the amount of electricity use per household varies tremendously across the country, the average American residential customer in 2014 used 911 kWh each month, meaning that in most parts of the country, a modestly-sized solar array could provide the equivalent of roughly half of an average customer’s electricity use.
The price paid for electricity varies across the country, depending on how it is generated and other factors. But according to the Department of Energy, the average national price of electricity to residential customers is about 12 cents per kWh. If a home gets 400 kWh a month from solar, it would cut the annual energy bill for the average home by around $600.
Since 2008, the cost of generating electricity from solar panels has been cut in half. The number of U.S. solar installations have increased by a factor of 17 over that period, and they now have the capacity to power the equivalent of 4 million average American homes. With solar panel costs expected to continue falling, solar energy may become an increasingly attractive proposition to homeowners. Enter your address at Google’s Project Sunroof to see the potential for solar energy in your location.