Snow is a beautiful yet occasionally problematic part of life for much of Canada. While wintry weather allows us to enjoy snowboarding and hockey, Snow can also present challenges when it comes to managing many of the systems we take for granted; solar panels included.
Studies and user experience have shown that like our roads and buildings, solar panels can still serve their purpose even in snowy conditions but how does snow affect solar panels in Canada?
Do solar panels work in the winter?
A key concern when using solar panels in Canada is the fact that accumulated snow can block the rays of the sun from reaching the photo-voltaic cells inside of the panels. In reality, light snowfall will slide right off the slick surface of solar panels when they are installed on a typical pitched rooftop.
Even when accounting for heavy accumulating snowfall, our examinations of data from studies like this one from the Northern Alberta Institute of Technology (NAIT), have found that only around 6% of annual production is lost due to snow on typical roof angles. This low percentage of loss is also due to the fact that in Canada, we get fewer hours of winter sunlight and the incident angle of the winter sun is lower.
Other studies looking at the impact snow has on solar production, like the one featured in the below video, have produced similar findings that in most cases snow doesn't impact production as much as we might first expect.
Although that video featured information about a snowfall study by the Department of Energy in the USA, the information still generally applies to Canada.
Accumulating snowfall would certainly pose a problem for off-grid or stand-alone systems where the only source of power is the solar array, but even in these cases, manually removing the snow with a brush is an effective solution. We discuss this further later on in this article.
But how does that 6% loss translate into annual electricity budgets? If designed properly, the overall impact of snow might cause an annual energy loss equal to $20 or $50 for a residential install.
With net-metering, your system can be designed so that the credit built up in the summer will match your needs through the winter, so your net annual energy charges can still be close to $0 over the course of the year.
Can snow damage solar panels?
How about the extra weight of the snow? Can the weight of snow damage solar panels? Many solar panel models are designed to withstand this extra weight from snow. Solar panels like Hanwha Q-Cells and Canadian Solar CS6K series are built to withstand at least 5400 pascals of force on the frame due to snow loading which is the equivalent of about 112 pounds-per-square-inch.
With all of these factors considered, snow starts to look like less and less of a problem. Simply taking the time to consider expected snowfall in the design of a solar power system eliminates most, if not all the potential problems.
What about snow and off-grid solar?
Let's go back to off-grid and stand-alone systems for a minute because this is where snow management actually deserves a bit of extra attention. Like we mentioned before, snow can be manually removed from the surface of the solar panels with a soft brush, just make sure that your safety comes first!
We do not recommend climbing on top of a 20-foot-high roof in the middle of the winter to brush the snow off your solar panels.
Additionally, any activity that involves something like a brush contacting the surface of the solar panels should be checked to confirm it won't void the manufacturer's warranty.
If you have enough space, your off-grid or stand-alone system can be ground-mounted to allow for easier maintenance and snow removal. This ground mounted option also allows you to choose the tilt angle which can contribute to better overall system performance.
Can't we just melt the snow?
There are currently technologies that use some energy to heat up the solar panels and help with snow removal. One potential issue with this technology in a roof mounted situation would be that the heat could cause water from the melting action to drip and re-freeze on the roof.
Other technologies like heat-tape or electric heat-lines have been brought up as potential solutions but again, the melting and re-freezing is still a problem here.
This re-freezing water might contribute to ice damming which could endanger the water resistance of the roofing material.
Additionally, the added expense of purchasing, installing and maintaining these solutions would likely be more than the cost of the 6% lost annual production.
With this in consideration, snow melting technologies may only be viable in large-scale installations or remote applications where the solar power is absolutely critical and no one is around to brush the snow off.
Just plan around it
When it comes down to it, simply considering snowfall and making the proper choices in system size and equipment selection will handle the biggest concerns that many solar power users in Canada will ever have with snow.
Net-metering allows grid-connected solar power users to build up a credit to offset lower winter production and a simple soft brush will fix most snow issues for off-grid users.
All of the systems we design accommodate for losses due to snow and we do our best to ensure that you get the best performing system for Western Canada's unique climate.