One of the oddest delusions is the idea that at high latitudes you can run a house, town, city, or country on solar panels coupled with batteries. The idea itself is so daft I often fear I am attacking a straw man to even discuss it. Yet, a reasonable number of people seem to believe this nonsense.
The most popular form of it comes in the following sound bite: “If you covered all of Britain’s roofs in solar panels, it would meet 100% of Britain’s electricity demand”. The claim itself is actually false, even if you simply consider total energy produced – and ignore the long stretch of winter when Britain’s solar panels might as well be disconnected from the grid. And what a glorious coincidence this would be, that covering all available roof space in solar panels would precisely match demand.
This belief in solar self-sufficiency has, unsurprisingly, reasserted itself in the wake of a Silicon Valley superhero (Elon Musk) creating a “game changing”/”disruptive”/”expensive toy for rich people” battery that can store electricity during the day from your solar panels. This, some hope, will let people disconnect from the grid. Here is how a BBC journalist recently finished a piece on “The town where one in ten have opted for solar power”:
However, moves to produce batteries to store home-produced energy could further revolutionise the economics of solar power. Should they prove effective, the town of Wadebridge would not only be self-sufficient in energy, but it could become a net exporter too. A British town exporting sunlight? Now you’ve heard it all.
Solar self sufficiency, or grid disconnection may be an option if you live in California – or maybe not, just think of getting through Christmas with a cloudy sky and nothing but solar panels and batteries to power the various activities. It will not be an option in Britain, or any other high latitude country.
The problem is rather straightforward: Winter. Britain’s electricity demand peaks at more less the exact same time as solar panels are producing minimal electricity. Let me reproduce below an old figure I created for Germany. In Germany, just over 5% of electricity demand is met by solar panels on average. However, on the worst days this can hit as low as 0.1%. For Germany to meet its year round demand from solar panels it will need something on the order of 1000 times more solar capacity than it currently has.
That’s if we assume they point put in place enough storage to store something like half a day’s worth of electricity demand, which is not an easy task. Alternatively, they could build less solar, but build enough storage to store a few weeks worth of electricity demand for winter. I could quantify why this is improbable, but that might be labouring the point.