A couple of years ago I did an article and short video on how shade affects solar electric panels. Solar pool heating panels are different, and shade affects them differently.
While it’s always best to avoid shading with any type of solar panel, sometimes there just isn’t a suitable roof or there isn’t enough roof space. Sometimes the neighbors have a big tree they want to keep. Sometimes it’s your own tree that you want to keep. Man-made structures including buildings, towers, and other obstructions may shade your property at times.
The good news is that shade is not as devastating to solar pool heating panels, or at least they are affected differently.
First and foremost, solar pool heating panels collect heat from direct solar radiation, but also from the ambient air when it is warmer than the pool water. If the roof is warmer than the pool water, heat can also be gained via conduction from the back side of the panel. Tree shade and shade from narrow structures like chimneys and towers are not nearly as bad as they are for solar electricity. As the sun moves across the sky each day, only a portion of the solar panel is affected. The rest of the panel continues to heat the pool.
Is it ideal? Far from it. But if you are in this situation the best course of action is often to oversize the system. Sizing the system so that part of the solar panels are in the sun will achieve the same effect if the total irradiance on the array is the same.
If you have a suitable unshaded roof we will always steer you in that direction. You can install fewer solar panels to achieve the same results at a lower cost. But when there is just no other option, installing solar pool heating panels in the shade is an acceptable alternative, as long as there is some sun on all panels at least part of the day.
We can help guide you in how much you need to oversize your system to achieve the desired results.