Determining the Renewable Energy Source for You

Assessing Solar Power Potential At Your Location

Most locations can make use of solar power as long as where you would install the solar panels would have a clear shot of the sun for most of the day (e.g. 9AM through 3PM). Most solar electric panels rapidly decrease in performance with just a little bit of shading. Literally the shadow of a twig upon a solar panel could cause it to decrease it's output by 30% or more.

The amount of energy you can get from solar electricity at your site, depends on your location in the world and the time of the year. Obviously, sites closer to the equator will tend to receive more solar power throughout the year than one's far north or south of the equator. Generally sites north of the equator receive more sunlight between the months of April through September, and sites south of the equator receive more during the opposite time of the year (October through March). As you can imagine, sunlight is also affected by the weather. Sites that frequently have long lasting fog or are overcast during large parts of the year will have less available solar power.

The measurement for the strength of the sunlight striking the earth at your location is defined as solar insolation. Using this value, you can determine how much energy you can generate through out the year for your site. Solar insolation data for all over the world and at different times of the year has been investigated and recorded. The peak, average and lowest annual solar insolation values for several different USA cities and countries across the worled can be found in the Reference Materials area of our AltELibrary. If you live in the USA, choose the city closest to you in the table and that will give you a good estimate of the amount of solar insolation for your location.

To determine the average daily amount of energy you would produce at your location, you would multiply the average annual solar insolation value times the total wattage of your solar panel array. As an example, let's say that you had a single 100 watt solar panel and you lived in Columbus, Ohio, which has an average annual solar insolation value of 4.15 sun-hours. To determine your average daily energy output out of that 100 watt panel you would multiply 100 watts times 4.15 sun-hours (100 x 4.15), which is 415 watt-hours (or 0.415 kilowatt-hours). This amount of energy would be about enough to power a color TV for a couple of hours every day.