Do solar panels really work during the winter?
I’ve mentioned solar power here on My Zero Waste before. While it doesn’t really come under the remit of ‘zero waste to landfill’, it certainly ticks all the boxes for a more sustainable lifestyle, and I know many of you are aware of the bigger, ‘green’ picture in your day to day lifestyle choices.
Here at Zero Waste Towers we have two small solar panels that we use to run the downstairs lighting. Mr Green has built some high spec LED light bulbs as these are several times more energy efficient than CFLs. When you’re generating your own electricity every watt counts!
While this winter wasn’t exactly harsh, I don’t know about you, but I noticed just how DARK it was. I use a SAD light box and I really needed it this year. It seemed that the skies were grey a lot of the time and the light didn’t really get through the clouds.
Our solar panels are photovoltaic and, during the daylight hours, they charge a 12 volt battery system made up of leisure batteries. These in turn provide low voltage energy to power all of our LED lighting.
If you read about solar panels you’ll be told that they work even on cloudy days, which is true, and, whatsmore – and somewhat ironically – they are more efficient when they are cold.
Cloud and snow
However, unless they are at that mysteriously perfect angle to the sun that seems to require the brains of a professor to figure out (and of course changes throughout the year), then the light-to-electricity conversion is less than optimum. This means that in the winter months, when the sun is lower in the sky, there is less electricity generated. In addition, less daylight hours and more likelihood of cloudy conditions further reduces the amount of electricity generated. So, on a cloudy winter’s day, the amount of electricity generated can be reduced by as much as 75 per cent compared to a summer’s day of full sunshine.
This power reduction during wintertime is very significant because it’s during the darker days and longer nights that we demand more electricity, especially for lighting. Another wintertime issue is that solar panels, depending on the pitch of the roof, can become buried under snow, so their light to electricity conversion drops to zero.
An investment for the future
The way to win is to have an excess of solar panels in order to compensate for the significant loss of conversion during the winter months and cloudy days, but then you need to take the cost into consideration. I appreciate the companies that are honest about this. For example, MyRedlandRoof, who advocate solar power roofs point out that the chief disadvantage of solar panels is the initial cost of installation. However, the cost of producing solar energy appliances is falling as technology develops and, as the cost of fossil fuels continues to rise steeply, solar energy becomes an increasingly attractive option.
Many people who have solar don’t run low voltage fittings such as ours: they feed the power from the solar panels into a mains inverter, then any electricity not used gets fed back to the grid for the householder (or solar company if it’s a free installation) to benefit from the Feed In Tariff. For most people solar energy is only advantageous during the day because there is no battery backup or store, making them reliant on utility providers at night-time.
What I love most about our setup is that even during a night-time power cut we can still run the lights! The bottom line is that, yes, solar panels DO work during the winter months but they are much less efficient. In an ideal world I’d have other sources of sustainable energy to use as well, such as a small wind turbine to generate electricity, geothermal for heating and biomass for hot water.
What about you – do you use any renewable energy sources at home? I’d love to hear about your experiences as we are still pretty new to all of this!