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Comment by destitude | Hacker News Reader

I'm fully off grid (even had utility power but had them remove it). Cook on electric, have electric water heater, using AC and have enough panels and batteries to not even need a backup generator.

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This is very cool. I'm guessing you must live somewhere with mild winters. Insulation can do wonders, but it can be overcast for weeks in the north.

Solar panels are so cheap that it makes sense to overbuild, such that even an overcast winter day meets your electricity needs.

I think that depends on where you are. I've heard of 20kW installations producing 500W in December.

Granted 500W isn't nothing, but what if it's snows?

That is about the numbers that we get in Sweden. Those months were solar production is lowest is also the months that consumption is highest for the average household, around 400% compared to the warmest summer months. As a result, energy prices are also significant higher during winter compared to summer.

My home's PV produces more energy than we use in a year, including heating. But the ~1:10 swing in generation from my roof in London UK between mid-winter and mid-summer is tough, and the storage to cover that interseasonally would currently cost about the same as the house and/or use ~50% of its volume. However, we import minimally in summer and export like crazy with the help of relatively modest storage.

Luckily there is this thing called a grid, and the UK has a lot of anti-correlated wind generation on it, which helps a lot.

All my detailed stats are here:

https://www.earth.org.uk/energy-series-dataset.html

Also see:

https://www.earth.org.uk/statscast-202012.html

In my experience this requires overbuilding by a factor of 10. That's not a good allocation of money.

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