How will shade affect the performance of my Solar Panels?

19 Jul

It’s common knowledge that vampires can’t stand garlic, that the Joker is Batman’s nemesis and that oil and water simply don’t mix. The same can be said about solar panels and shade. They simply don’t work well together.

Solar panels installed by Eco Alternative Energy at a house in Ontario

Solar System installed by Eco Alternative Energy

Solar modules are designed to convert solar radiation (otherwise known as sunlight) into electricity which will then either be sold to your local Hydro Company in a grid tie scenario or used to charge batteries in an off-grid system. When a panel is blocked by a shadow (either by a cloud, a chimney, or tree branch, etc), it can reduce the performance of your system dramatically.

Without getting too complicated, imagine a standard solar panel on its side, in a landscape position. Now divide the solar panel in two with a top half and a bottom half. Each half is a circuit interconnected together in series (30 cells in each half for a total of 60 cells). When you shadow any of the cells in either of these two half’s, the voltage of the solar panel will drop in order for the panel to protect itself. Even if only one of the 30 cells in that section of the panel is covered,  it will have a dramatic effect on that half of the panel and potentially on the system as a whole depending on whether you decide to go with a string or micro-inverter (future blog coming soon).

Some common shade considerations you will need to look out for include chimneys, hydro wires, dormers, TV antennas, snow, neighbouring houses and of course tree branches (doesn’t really matter if its winter or summer as the shadows of branches in the winter alone can still have a significant impact on your system). Do shadows from these obstructions mean that you can’t add solar to these areas of your roof? Not necessarily.

Solar Pathfinder: Eco Alternative Energy

Solar Pathfinder: Eco Alternative Energy

Your solar installer should have the knowledge and expertise in choosing the best areas of your roof to add your panels that will maximize your return on investment. He or she may avoid certain areas due to constant shade obstructions but it’s important to keep in mind that some shadows may affect a panel in the morning however may not affect the same panel the rest of the day – resulting in overall good performance. That’s  because shadows move throughout the day as the earth moves (but I know you already knew that).  Solar installers should have the tools, like a Solar Pathfinder, that will allow them to make educated decisions on the best places for you to add your panels. With the Solar Pathfinder tool, they should be able to predict your solar systems performance based on any obstructions you may have on your roof. It doesn’t matter what time of year they do the analysis – the tool is smart enough to give results for the entire year with surprising accuracy.

We hope you found this article on shade helpful. If you would like to have a shade analysis done on your roof, drop us a message here or call 1-888-907-5848. We have three locations to service you (Toronto GTA, Sharbot Lake and Peterborough) and we would be happy to help you out. You can also find out about other posts to many of your common questions here on our blog.

If you are in Ontario, Canada and would like a free online evaluation of your property for solar, feel free to fill out the short form below and one of our experts will get in touch with you in 1 business day.

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