Good morning friends!
During our Ask the Author feature, we got this question posted on our blog.
“I’m interested in putting up solar panels, but I live in a century home and I’m not sure if my roof can handle the weight of them. I have 10″ roof boards on the roof deck and the rafters are 2×4 fir with a small plate at the top joists, no other trussing. We installed knee-walls 4′ in from the edges several years ago to reverse some bowing. Would solar panels work? Is the return on investment worthwhile? Shingles were replaced 2 years ago.”
We get very excited when people ask these questions, these are the fun ones to answer. So first I would start by saying there is no blanket answer for whether houses can support solar panels or not. Each house should be evaluated on a case-by-case basis. Each house should be independently viewed by an engineer so they can get all the roof information (pitch, spans, type of roof, orientation, etc.).
The good news is that solar panels don’t add many pounds per square foot. Depending which panel contractor you go with, and the panels they use you could expect to see 2-3 pounds per square foot out of a 3×5 panel. So, this really isn’t a lot of added weight on a roof. The snow load factor used for calculating trusses is typically 40 lbs/sq/ft or greater in Winnipeg.
Now tackling return on investment… This one is typically a bit harder to calculate. This one you really need to consult with a solar contractor. They will determine roof slope, orientation of home, tree cover etc. to determine where to install panels to maximize their value (For Winnipeg the dream is typically a 7/12 pitch roof with a slight skew from straight south). They should be able to provide feedback on estimated generated electricity. From there it becomes a simpler math game to calculate expected payoff.
Some things to consider for expected payoffs: 1) If you can afford it up-front, it will reduce the cost to own down the road. 2) Are you planning to have a battery to store your excess energy, or will you sell to the grid? 3) What is the value of having some potential power source during an outage?
I hope this helps inform your decision. If you would like us to help you out along the path, contact us. We’ll get you connected to engineers and solar contractors to help make your decision!