Alaska’s Willow solar farm is sited a few hundred miles south of the Arctic Circle. While 85% of the northernmost US state has some level of permafrost, it is surprisingly sunny. And solar panels do not need heat; they need sunshine.
“Colder temperatures do not have a massive impact on solar panel efficiency,” says Ross Mains-Sheard of Versofy Solar.
“In fact, you may lose efficiency when the temperature gets too high. Solar panels do not convert heat energy into electricity; they convert solar radiation into electricity by making use of the photovoltaic effect.”
Fewer sun hours = less power generation
Ross explains that the main reason solar generation is reduced in winter months is fewer sun hours. The angle of the sun is also much lower in the colder months compared to summer months and this can mean that some users may be affected by a 50% generation loss in winter. Less direct sunlight reaches the panels and therefore production is reduced.
The ultimate solar panel angle for production fluctuates over the course of the year. In summer and the warmer months, it would be at 30°, while in winter the angle would be closer to 45°.
“Moving panels and changing the angle with the seasons may increase generation but the costs associated with this will be very high,” Ross warns.
A solar tracking device (which points panels directly at the sun, following its movement for better production) and optimisers that reduce losses caused by shading do improve generation. But Ross says they are not used much in the residential market due to prohibitive costs.
“Rather identify your generation peak for summer and winter months and ensure that your panels get close to that level on a regular basis,” he advises.
“These tests can only be done in ideal weather conditions.”
“If you use an experienced, professional installer, they will study your site and establish the best spot for the panels – ideally in a space that is north-facing and never in shade. They will then mount the panels at a 30–40° angle. This will give you the best summer and winter production.”
Shading is a solar array’s worst enemy. While solar panels can still generate power after a rain shower (because light travels through the water), on an overcast day, your panels will generate electricity at an incredibly low rate.
“Interestingly enough, scattered clouds on a sunny day often cause a phenomenon called Edge of Cloud,” Ross adds.
“This is a sudden increase in the amount of light energy due to reflection from the passing cloud, which focuses more sunlight onto your solar panels, giving you a spike in production.
Most debris will slide right off
Does the accumulation of environmental factors (hail, frost, leaves, debris etc.) affect solar panels’ structural integrity and electrical performance?
“Because the panels are mounted and installed on a mounting structure, the weight is distributed evenly, and due to the angle at which they’re installed, most debris will slide off,” Ross answers.
He emphasises the importance of washing off dirt and dust every six months to ensure there are no generation losses.
“Dust and dirt can affect your generation by approximately 5%. You can clear the panels simply by spraying them with water from a hose pipe.”
Is ice a problem?
“Like rain, ice is clear, and it does not block sunlight from reaching the panels therefore generation losses are at a minimum. Solar panels do not convert heat energy into electricity but with that said, the panels still generate their own heat and therefore any ice will melt during the course of the day.”
Heavy cloud cover and shorter hours of daylight will affect your solar system’s generation capabilities, but cold temperatures, rain and ice will not – as long as the sun is out and your panels are not in the shade, your solar array will still produce electricity.