PV solar panels generate power, not heat, by absorbing light. Therefore, the sun's potential for decreased intensity and shorter daylight hours throughout the winter may impact your solar system's output.
Depending on where you are located, the output decline can be different. The panel's brand, the system's size, and the panels' angle are some examples of variables that can affect these statistics.
Theoretically, the tilt of the panels should be increased in winter to line up with the sun's lower arc in winter to maximise production, and the panels' placement could be changed to prevent shade. Unfortunately, in practical terms, this rarely occurs, as solar panels usually get fastened in a fixed position.
Will my panels work during the winter? If so, how effective will they be?
Many homeowners believe in the misconception that their solar system draws electricity from heat. They become concerned because they think their system’s output will decrease in winter. This understanding is not correct.
Solar panels absorb light to produce electricity, not heat. In winter, yes, the temperature does fall, but the sun’s light does not disappear. However, the sun is lower in the sky and a further distance away in winter, meaning the rays do not hit solar panels at an optimal angle and with the same intensity.
Daylight hours are also less in winter, meaning less sunlight per day. So what does this mean for the output of your solar system in Winter?
What solar panel output should you be expecting during winter?
Your solar system will produce less electricity in winter than in summer. In Australia and NZ, the drop in output varies in each city. In winter, solar system output drops to 64% of its average daily production in Sydney. Brisbane has the best conditions in winter, only dropping to 73%. Melbourne has one of the bigger drops, where solar output reduces to 50% of winter’s average annual daily output. However, Adelaide is not much better, falling to 52% of the yearly average production. Perth sits at 56% in winter.
These include the panels’ brand and low-light performance, the system size, the panels’ angle, and many more. Use these numbers as a general guide, so if your output is reduced in proximity to the mentioned percentage, you know your PV system performs as expected. However, if you drastically drop further than these numbers, you should contact your installer for advice and maybe a site inspection.
The best angle for your panels during winter
The standard recommendation for the angles your panels sit at is the latitude angle of your home. While this angle will still be beneficial, the sun has a low arc throughout winter. This means to get the absolute most out of your panels, you would have a slight increase in the tilt of the panels. This will ensure your panels are still perpendicular to the sun, even with the lower arc.
It may be a hassle for you to adjust the tilt of your panels. So, if you struggle to receive enough electricity throughout winter, you can plan to set your panels with an increased angle from the initial installation. Of course, you will have less output potential in summer, but if it is an issue that your output drastically crops in winter, this may be worth it.
Then again, if you do not install on a flat roof, where tilt angles are an option, and install the panels onto an angled roof directly – the whole question is academic, as in 99% of installs, the installer will follow the angle of the roof.
Shading in winter
During winter, the lower arc of the sun causes more shading than average. This means your panels could have more shading, meaning less output. Again, you need to consider the potential of this happening during the initial installation. If there is already some shading on your panels that will be escalated during winter, adjust the positioning of your panels, or trim back some of the offending branches – in the case of trees.
So yes, solar panels work well through the winter; the overall output is less than in summer. So if someone assumes panels have no output during winter, this assumption is incorrect. If your system is bigger than 6 to 8 kW, it will produce adequate electricity to supply your home’s needs.