You're probably here because you saw an auto-tweet from my solar panels. Yes, that's right, my house is wired up to the Internet of Things!
Here are answers to some questions I get asked about them. If you've got any others, please stick them in the comments section or ping me a message.
How much did the panels cost?
What's the payback rate?
We're expecting the panels to pay for themselves in about 10 years. The government gives us tax free cash for every kWh we generate. Our electricity bills are lower. Any excess energy goes into our immersion heater to heat up water. The rest is sent back to the grid.
How much power do they generate?
It varies. According to this solar calculator we should generate around 3,400kWh per year. Obviously, that will vary throughout the year.
How much electricity do you use every day?
Based on our last four months (September-December), we use an average of 8.5kWh per day. There are only two of us in the house, but we have a lot of computers running. We've switched to eco-lightbulbs, and have high efficiency kitchen appliances.
According to the UK Government, the average household electricity usage is 3,300kWh per year. That's ~9kWh per day.
So, theoretically, we could generate enough solar power to offset our entire energy consumption.
Is British weather sunny enough to make this viable?
Yes and no!
Even in winter, close to the solstice, I was still able to generate ~10kWh on a clear day.
A perfect day for solar power in Oxford. No cloud cover means 10kWh generation! Not bad this close to solstice :-) pic.twitter.com/V5T6R8T6nL
— Terence Eden (@edent) December 29, 2013
A few days later, however, the rain and fog resulted in this pathetic specimen.
Today, my solar panels generated 1000 Wh! pic.twitter.com/SMoviCO5Wq
— Terence Eden (@edent) January 1, 2014
Can you go off grid?
Not really. If there's a power cut, the inverter stops feeding energy back into the grid lest it electrocute someone.
That said, all my battery powered gizmos charge during the day - so they'll be ready come the zombie uprising.
I am thinking of adding a UPS to keep my computers running in case of power failure.
How did you hook the panels up to Twitter?
What does "Feeding Into The Grid" mean?
During the day, if I'm out, I still have electrical appliances running - computers, security cameras, WiFi, fridge, etc. Let's say that the total draw of those is 500W.
If my panels are generating 600W, the electricity used by my appliances comes directly from the sun and not my electricity company.
The excess energy (600W - 500W = 100W) flows back through my meter and is used by everyone else on my street. It also has this side effect:
But solar panels don't work during the night!
An excellent observation. Luckily, I get to work from home a far bit. I also schedule my washing machine and tumble dryer to come on around mid-day. Anything I don't use goes into my hot-water supply. Anything left over after that goes to giving people on my street clean, green energy.