Did I make a mistake?
Friday, June 21st, 2024 at 07:18pm
Today is the winter solstice and over the last few days it has been quite clear that winter has set in in Melbourne with headlines such as “Melbourne shivers through coldest winter day in four years…” so it seems appropriate I give some updates on how my solar, AC and heat pump hot water system are going.
A big question I asked myself was whether I made a mistake in getting my gas disconnected. Previously I would have the central heating on a schedule that I didn’t think about and my entire house would be warm at the times that I was awake. The AC units in my study (during the day while I am working and then in the evening) and bedroom (a bit in the morning for when I wake up and then a bit in the evening before I go to sleep) do a good job if I close the doors to those rooms, which means the other rooms (kitchen, bathroom, lounge) are cold.
It isn’t actually that bad, but it is noticeable when I move from room to room. Thanks to my monitoring I could also track that when I was in my study that the CO2 would climb to 1500ppm and at times I do feel a bit sluggish. My mitigation so far has been to get up every hour and go get a drink or go to the bathroom, this lets enough fresh air in to drop the CO2 down to around 600ppm from where it will start to climb again. The alternative is to leave the door open (like I used to do) but then the AC unit is trying to heat my entire house which is not efficient.
With the shorter and cloudier days there has been a noticeable drop in how much my solar panels are generating. At the peak of summer they would generate almost 30kWh over the day, but the best I have seen recently is 17kWh on a day that was sunny all day, but that is the difference between 13 hours of sun high in the sky versus about 8 hours of sun that is lower. Though even on a day that rained all the way through the panels managed to produce around 3kWh which was about a third of my consumption for that day.
I could also notice a pattern of the solar generation being best in the early afternoon, the day would start out cloudy and the clear up for a bit. To better take advantage of this I changed the schedule on my heat pump hot water from 10am to 1pm with the intent to run it both from solar that I am generating and also to be in a warmer part of the day so it should run a bit more efficiently. I don’t have a way to actually measure this, but it seems like the right thing to do. What I can also see is that where it would run for just over an hour when the ambient temperature was above 20°C, but now when the ambient temperature is below 10°C it is running for a bit over two hours.
All of this is just the detail, what really matters is the long term so it won’t be until the start of next year that I can sit down with the data and compare 2023 with gas heating and no solar against 2024 with solar and three heat pumps…
