Thursday, 15 September 2011

Your solar panels will still work come Winter

Despite the UK averaging around 48% overcast days in the year, solar panels, both the electricity generating kind (or photovoltaic to give them their proper name) and solar hot water panels continue to operate.

But what about the Winter?

Surprisingly, solar panels work even better - especially after a fall of snow. Providing the panel itself isn't covered, the amount of light produced by reflecting snow makes it ideal generating weather.

Solar panels also operate more efficiently in the cold - something to do with the cooling effect allowing for higher voltages being produced which results in higher wattage.

Providing the panels are clear of snow themselves, which might sound like a chore but given they should be south facing, then they'll melt off pretty quickly.

Some owners have gone to ingenious lengths, constructing extendable brushes to clear the snow off. Be careful though that you don't scratch the panel surface or put your safety at risk by over-reaching or using ladders etc to gain access.

Most owners just wait for the sun to melt any accumulation naturally.

One other thing you might be able to enquire about is solar panels that may have an additional coating which aids dirt and deposit washing off through natural rainfall.

A bit like the coatings you can now get on self-cleaning glass - very popular with glass roof conservatories - helping your panels maximise your return.

photo credit: david wiley

1 comment:

  1. From the datasheet of the pv module ("the solar panel") there should be a value for the change in power per deg.C. This can be used to estimate how much better then panel is in cold weather. For example, my 235 Watt panels make an extra volt; 31 volts each in cold bright weather, which with proper inverters goes straight to extra power of a couple of %.

    For much of the time in winter, under a dull grey sky, best output is reduced. Current is in proportion to the amount of light arriving and voltage goes down a little bit too; to 25V and 5% of the rated current, down from 30V at 80% current under good sun. In unusually cold weather this shifts up a volt to 26V per panel at 5% current. So, expect to want at least eight solar panels to run the fridge and typical household baseload of 100W for free during a dull grey day. Be sure to get a trusted inverter plugged in to a big set, or start sooner with two good panels from anywhere and a grid tie inverter off ebay.