Cold, cloudy days in June were a good test of the energy cost for active heating to remain comfortable indoors. The total energy bill to live comfortably in our high-efficiency, all-electric home was a reasonable $2.50 per day.
During May, the colder, cloudier days meant the house changed from passive to active heating mode. The air conditioner was handy to keep the indoor temperature within the target comfort range. Less solar power production and higher electricity consumption left us with a $43 energy bill.
April marks the end of a long run of days of excess solar power exports and passive cooling. Shorter, cloudier days reduce power production. Colder temperatures mean the house has moved to passive heating, with just a touch of active heating using the air conditioner. It's still comfortable indoors but the monthly energy cost is expected to rise from here.
Longer, warmer days reduced the need for any form of heating to keep indoors at a comfortable temperature. The extra sunshine increased solar power production so we had more than enough electricity for household demand and charging EVs.
A few cold, but sunny, days allowed our home to show off what it can do with sunlight. Light streaming through the large north facing windows quickly warmed the house in daytime. Solar panels produced more than enough electricity to supply our all-electric home's needs.
A run of cold, cloudy days was the ideal opportunity to program the SolarEdge inverter to import offpeak power to charge the battery at night. Without this option, I would have paid peak power rates for electricity the next day when solar production wasn't able to meet household demand.
Learning how to help the passive solar design features keep us warm in Winter is a useful exercise. Sunlight is all we need on clear, cold days. When it's cloudy, we use the heat pump to stop the concrete slab thermal mass cooling too much.