In my previous post, I touched on some of the common myths surrounding solar. One of the most common misconceptions is that solar panels are ineffective in cooler climates. Let’s look at this in more detail.
Solar Panel Efficiency in Cold Weather
As I mentioned in the last post, solar panels harness sunlight rather than heat from the sun and therefore not only do they work in areas with cold climates, but they can be more efficient in cold conditions. The reason for this is that solar panel efficiency is determined by their operating temperature, which is influenced largely by ambient air temperatures and sunlight intensity. Sunlight intensity and duration are two important factors that affect solar panel efficiency. Yet surprisingly, higher temperatures can lower their energy output, reducing their overall efficiency, while efficiency is improved when temperatures are lower.
Furthermore, because prolonged exposure to high temperatures can reduce the lifespan of photovoltaic panels, solar panels are likely to last longer in cooler climates – bearing in mind that strong winds can also damage solar panels (either directly, or indirectly as a result of damage sustained from flying debris).
Temperature can affect that rate at which electricity flows through an electrical circuit (in this case your photovoltaic panel) by changing the speed at which the electrons travel. As temperatures increase, the flow of electrons in the PV panel become weaker, resulting in lower electrical current and reduced efficiency.
Solar Panel Efficiency on Cloudy Days
Because solar panels use sunlight rather than heat to generate electricity, they can still produce power on overcast days – they may lose some power, but will continue to produce energy as long as it is light outside. When clouds block out the sun, or during dark, stormy conditions, output will drop significantly. However, because of their reflective properties, in certain conditions clouds can actually enhance the output of your solar system. On days when there is light cloud cover, sunlight is diffused through the clouds to reach solar panels erected on your property. On partly cloudy days the sun will penetrate the gaps in the clouds and your PV panels will receive both direct sunlight AND light reflected by the clouds.
Does Snow Affect Solar Panel Efficiency?
Snow can have both negative and positive effects on the efficiency of solar panels. During a heavy snowstorm it is likely to be dark and dreary, which will lead to a drop off in the performance of your solar system. However, once the storm has passed the ground will be blanketed with a layer of fresh white snow that will reflect light to your solar panels, thus improving the energy output. This will improve even more once the sun comes out and reflects off the snowy landscape, resulting in an increase in light intensity.
Because solar panels are made of a smooth surface and are typically installed on a sloping roof or at an angle so that they are optimally positioned to capture light radiated from the sun, snow tends to slide off with relative ease. Also, PV panels are dark in color to prevent light from being reflected off their surface, and thus will also absorb heat as well as light. Consequently they will retain a certain amount of heat, which facilitates melting of snow that accumulates on the surface. During bouts of heavy snowfall, solar panel efficiency may drop significantly if a thick layer of snow accumulates on the surface of the panels; but once the sun comes out, this will melt relatively quickly and slide off the panel. Alternatively, they can be cleared by hand using a roof rake or something similar.
Optimal Climate Conditions for Solar
The most optimal conditions for solar power generation is in areas where it is cool and sunny. In fact studies have shown that some of the coldest areas in the world, such as the Himalayas and the southern Andes, have the best solar potential. Clouds and snow can improve efficiency by reflecting light onto the panels, while rain and snow can wash dirt and debris off your panels to keep them clean, thus improving their efficiency when the sun comes out again.