… but solar panels don’t work in the winter!

I’ve had my solar panels since October 2011 (details about my system can be found on this post) and I’m always telling people how good they are. When I tell people about my solar panels, I get one question – “how much do they generate” and the second is a statement that always makes me want to bang my head against a brick wall – “… but solar panels don’t work in the winter!” Don’t they??

When I first started telling people they should buy solar panels, all I could them was how much electricity they would generate and potentially cut from their bill, but since then I’ve added monitoring to the system which uploads the data to the internet. After the person I’m talking to has used the infamous statement about not producing electricity in the winter, I then proceed to show them the stats from my solar panels.

In the UK, winter solstice is a day between 20th and 23rd December and for more than a week each side of winter solstice, there are less than 8 hours of sunshine in a day. It’s quite literally the worst generation time of the year for solar panels in the UK – especially combined with the weather that you can get at that time of year… But when the sun does shine in the winter, you can get very good solar output days!

This December gone, I checked my system from work during lunch (as I do most days! sad, yes I know…) and noticed the solar panels had heated the hot water. To heat the hot water, there has to be enough energy generated by the solar panels to not only cover the house’ standby usage (350 ish W/h), any additional power being used by family members and also the 1kW/h immersion.

What’s more impressive is that the date was 16th December!
(the red block indicates the immersion is switched on)

In fact we even had brief solar water heating on the 19th and 20th but they aren’t as visually impressive…

But what all three of those charts show is that solar panels do work in the winter. They can even generate enough electricity to cause a surplus and power devices around the home!

It is true that the panels do not generate as much electricity during the winter, due to the angle of the sun in the sky and the length of the day, but we still generate in the order of 100kW/h of electricity each December.

And on a perfect day, it’s possible to generate 9kW/h.

Home Monitoring (home made) – Results

And finally the results of all work!

There isn’t any change on the first graph which shows generation and import (yes, it should be consumption, but I have yet to work out the right values for the addstatus service).


The next graph is the result of all the hard work. I’ve set it to use v10 and v11 because of the colour contrast. As you can see in the graph, the solar hot water was powered a handful of times during the morning, boosting the temperature of the hot water a little. The results will be far more dramatic in the summer.


And that’s pretty much it, until next time! Maybe a weather station next time 😉