We can create a sun chart to plot how much direct sunlight your site will be exposed to each day. The sun chart helps us first to determine if solar power is a good option for a client, and then helps us evaluate where to place solar module panels. The sun chart shows the movement of the sun across the sky, and shows us the approximate amount of sunlight the site will receive over the year.
We use two angles to plot the position of the sun. The azimuth is the angular distance of the sun from a fixed line. Here in New Jersey or Pennsylvania, we use a line that runs directly south, because solar module panels are placed south-facing in the northern hemisphere. For example, at noon, the sun is directly overhead in the sky, so the azimuth angle is zero.
The second angle used to chart the sun’s position is the elevation angle. It is created using a line which is parallel to the ground and a line running from the ground up to the sun. For instance, at noon, the angle is 90 degrees. At sunset when the sun is on the horizon, the angle is zero. These two angles are used to graph the sun’s movement through the sky over a period of a day.
The sun chart can be used to plot the sun’s movement in the sky throughout all four seasons. The changing seasons affect the length of sun exposure each day. Charting the exact sunlight exposure for each season will help us determine the correct amount of solar module panels you’ll need to power your home or business through even shorter days, like the summer and winter solstices.
A sun chart also accounts for impediments in the skyline. Things like trees, buildings, and towers can block the amount of sunlight your site receives. The sun chart allows us to determine if these impediments will prevent your site from receiving adequate sunlight exposure. We may find that your roof is not an optimal location for placement of solar module panels, but there is an area of your yard that receives perfect exposure where solar module panels can be mounted.