Generating Solar Electricity in Mid Winter

Donnachadh McCarthy
Wednesday, 20th January 2016

Donnachadh McCarthy is generating so much electricity from a small solar array on his house, he is even able to switch on the heater and remain a net exporter of energy to the grid.

Coldest winter day and the sun heats my office. It is the little things in life that can make an ecological campaigner excited!

When I replaced my solar electric panels, I had hopes that over the year I would become a net exporter and carbon negative house again. My new solar array is a smallish 2.6kW system as that is all my small roof could take. The usual size is 4kW for a family home. It was a replacement last October for the original system installed in 1998 that I donated to local charity.

I had not reckoned, however, that the new (modest) system would help not only take care of my electricity carbon footprint but could also make a contribution to heating the house in winter also.

Electricity is about 30% of the average homes carbon footprint but many commentators forget in all the talk about electricity that heating makes up the bulk of a home's carbon footprint at 70%.

Anyway, Tuesday 19th January 2016 was the coldest winter's day so far in London. It was lovely and sunny and the dial on the solar monitor soared to about 1.1kW as lunchtime approached.

I suddenly thought about the electric oil heater that I have in case of emergencies when I am sick or unable to put on the high-temperature smoke-free zone compliant wood-burner that I usually use for carbon neutral heat in winter.

For some reason I always thought the solar panels would never produce enough to run an electric heater. But yesterday I got out the Watt monitor and found one section of the electric oil heater used 900 Watts and the other 1,000 Watts.

So I turned it on in my office/bedroom and was delighted to see the room temperature rise to 16oC (it was 2oC outdoors) and astonished to see even with the laptop and fridge on, I was still exporting to the grid.

Naturally it lasted about 1.5 hours but that was long enough to make the room warm by my standards and it remained above 14oC for the rest of the day, so I never put on the wood burner, when normally on a day as cold as yesterday, I would have gone through up to two baskets of locally sourced, untreated waste wood.

Of course, the major reason the heat lasted the rest of the day is because my bedroom/office is the best insulated room in my 1840s terraced cottage. It has solid wall insulation, triple FSC wood glazing and a thick loft insulation above it.

This little discovery whilst not a mega breakthrough, was enough to make me happily excited this week.

Solar Outputs in January

On a wider note, whilst it has not done it every day, so far in January the system has on average produced 1.5kWh electricity per day, which is exactly my daily average consumption, someting else that I did not expect in winter from the replacement system.

Since the solar feed-in-tariff was reduced on the 15th of January, the industry still claims that returns on investment are up to 5%. I reckon they are exaggerating but it is definitely a worthwhile way of investing between £5,000 to £7,000 if you have it to spare or can borrow it to help save the planet and keep the solar industry alive so it can continue to reduce costs, until it is cheap enough for everyone.

I have never bought a car in my life and really feel far happier having invested in solar panels instead.

Create a lovely (low carbon) day!

Donnachadh McCarthy is the co-founder of Stop Killing Cyclists and the author of The Prostitute State - How Britain's Democracy Has Been Bought.

Further resources

Learn how to build your own small-scale solar system in the new issue of Permaculture (PM87) out at the end of January 2016.

Energy Revolution

Also from Donnachadh McCarthy: UK government erodes eco-campaigners' right of free speech

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