Solar Electric Panel Shading

Because of partial shading one part of the solar panel generates lower amount of energy as compared to the other non shaded part.

Solar electric panel shading.

A solar panel consists of a number of cells in series which makes up a total voltage of around 17 to 23 volts for a 12volt panel. Setting up the solar panel where there is no shade is the best way to avoid the loss of output. What we learned about shading. Many residential properties are situated in green spaces and constantly growing trees and foliage can encroach on solar panel setups.

This is great for a sailboat with lots of shadows from lines mast boom etc or a cabin in the woods with varying shadows throughout the day. Intuition suggests that power output of the panel will be reduced proportionally to the area that is shaded. Although it probably goes without saying shading is not good for solar panels. However this is not the case.

Each panel works independently. A shadow cast on even just part of one solar panel in your solar array can potentially compromise the output of the whole system. When a solar cell is shaded it loses power. A typical solar panel is made of 60 individual solar cells wired together.

But this is not always possible. That loss of power increases electrical resistance within the cell which in turn blocks the flow of electricity coming from upstream solar cells. As the amount of power generated in shaded non shaded parts differs it leads to overheating which in turn reduces the total power output of the solar panel. In his book renewable energy and efficient electric power systems stanford university s gil masters demonstrates how shading just one out of 36 cells in a small solar module can reduce power output by over 75.

When shade hits them the first thing that happens is the current goes down. When there is shade on solar panels it will reduce the current of that panel. What fewer people understand however is just how important it is to avoid shading as much as possible. Now if shade comes over the panel the current could drop to 3 amps but the voltage stays the same resulting in 52 5 watts 3 amps x 17 5 volts.

It is possible for a panel to put out quite high voltage and no significant current. For this reason it is hugely important that your solar energy system remains out of shade throughout the day wherever possible. Shade on your solar panels can come from several sources. Diodes regulators and solar panels.

Solar panels in parallel and series is a really important topic though especially if they re shaded so we ll leave the best till last. Let s say you have a panel that has a rating of 17 5 volts and 5 8 amps it will produce 100watts. If one panel is shaded it will not affect the entire solar array.