The Highveld winter drought broke this past weekend with a two-day deluge. The soil needed the rain, but when you ordinarily heat your water with just the sun, it’s painful to switch the power on for the geysers. I cheered myself up with the thought that I could check how much electricity I would be using without my solar hot water system.
My home’s consumption for this sunless Saturday and Sunday averaged 30.5 kilowatt hours per day. In comparison, on the four previous weekends I was using 12 kWh/day. Assuming that hot water accounts for the difference, the sun ordinarily saves me 18.5 kWh/day, cutting my electricity bill by more than half. (I monitor my consumption using a customised spreadsheet you can download here.)
This is very close to the 19 kWh in savings I calculated in a different test here. My solar system is large — with 3 flat panels, 1 evacuated-tube panel and 600 litres of storage — and the rest of the home is very efficient, so I couldn’t promise such dramatic results on every house. But this gloomy weekend tells me that solar is saving me at least R9,000 a year, not to mention keeping 5 tons of carbon dioxide out of the atmosphere.
That’s a sunny thought no matter what the weather.