Planning & sizing a solar sytem

In sizing a PV system the first two factors we work from are the sunlight levels or insolation values from your area and the daily power consumption of your electrical loads.

Insolation:

Insolation or sunlight intensity is measured in equivalent full sun hours. One hour of maximum, or 100% sunshine, received by a module equals one equivalent full sun hour. Even though the sun may be above the horizon, for example, 14 hours a day, this sit e may only receive six hours of equivalent full sun. Why? For two main reasons. One is reflection due to a high angle of the sun in relationship to your array. The second is also due to the high angle and the amount of the earth's atmosphere the light is passing through. When the sun is straight overhead the light is passing through the least amount of atmosphere. Early or late in the day the sunlight is passing through much more of the atmosphere due to its position in the sky.
Our sun trackers can help reduce reflectance but cannot help with the increased atmosphere in the sun's path.

Because of these factors our most productive hours of sunlight are from 9:00 a.m. to 3:00 p.m. around solar noon. Before and after these times we are making power but at much lower levels.

When we size solar modules, we take these equivalent full sun hour figures per day and average them over a given period.