I think a lot comes from the solar as I was previously running the heat pump. For next winter I'm going to re-write the software for the solar controller to log hours it is active.
I think the biggest change is as a result of the under-floor heating as we have a huge thermal mass that gets charged up by the solar during the daytime. Even in mid winter on partly sunny days there was a big difference in power usage by the heat pump. The last week of January was very sunny and in 7 days our electric usage was only 166Kw. We're lucky to live near the Mediterranean where we don't suffer from very cold days and generally have lots of sunshine.
I must admit that I was very surprised at the low power usage, I had to re-check my readings more than once, especially as we had increased the heated space substantially.
Previously I didn't think that solar central heating was feasible but now, when supported by a heat pump, under floor heating and, essentially, good insulation, it certainly is.
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