Climate Friendly Retrofit Part 8: Solar, Microgeneration, and Energy Usage

  • When excluding hot water and vehicle charging, our home uses between 6 and 9 kWh a day depending on oven and washing machine usage. Sadly, oven usage is hard to shift out of the dreaded 4–7 pm window, but we’ve been able to shift our clothes and dishwashing to times where we know/see excess solar energy thanks to scheduling functions. The main point here is we haven’t changed our lifestyle/times we do things, only that we use the schedule function rather than starting things straight away.
  • Our hot water has nearly exclusively been heated by solar during this period other than a few places where I was still working out the automation. Our setup is such that the MyEnergi Eddi will divert excess PV into the immersion heaters on our Mixergy, and while this might be as low as .1 kWh at times, the tank can scrape 3–6 KWh over the day leaving us with a full tank by the end of most days (occasionally over 2 days). As we get to winter, we’ll see how we can get the solar to interact with Mixergy’s smart charging, and his interplay is going to require a blog of its own.
  • Our electric moped, which my wife almost exclusively uses to drive 16mi to/from work, needs roughly a 5.5kwh charge (30% of battery) per every commute, but because she goes in 2–3 days a week, we can normally grab that from excess solar if there is a day in between, otherwise, we can schedule charging to time with Octopus Go overnight tariff at 5p per kWh.
  • Our BEV (ID.3) has been the biggest change from what we expected. With our previous EV, when we lived in the city, we did not have a charger/driveway at home and had to get used to what EV driver’s call “grazing.” That is grabbing small amounts of electricity when out and about, at supermarkets, train stations, cinema, etc… We had anticipated charging primarily at home in this house, but with a battery that is nearly 1/3 larger than our last EV, our habits mean that we only really charge at home when there is LOTS of excess energy, or we need to leave at 100% charge for a long drive. In August, for example, this has only been 78 kWh (the equivalent of 283 miles or so of driving.

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