'Hours of free electricity' - maximizing the benefit
To get the most out of the ‘free’ hours, we have to do one of two things:
- Do something expensive during a free hour that we would otherwise do at some other time, or
- Do something during a free hour that we wouldn’t normally do at all.
(1) means that the activity involved could cost ~25p less than otherwise. (2) means we’re getting something for nothing.
It’s rare that I use 1kWh in any hour, with a couple of exceptions
- Using the electric shower. At 9kW, it’s the greediest appliance I have. From September to May, I have to defrost the bathroom using its 2kW wall-mounted fan heater to make it bearable in there. I haven’t needed to do that every time for the past few weeks, but it’s still uncomfortable if I don’t.
- Every couple of weeks, I do a frozen pizza - 16-18 minutes at 200ºC. Even less frequently, I do a plateful of frozen oven chips as a treat for supper - 20 minutes at 220º. These activities can cost up to 1kWh each, showing up as an alarming spike on the half-hourly usage chart.
- I can’t think of anything else …
So, I’ve been using the free hours - 10-11 and 11-12 - that OVO offers me on a Sunday morning to take a luxurious long shower. It feels a bit weird wandering around the house dirty in nightwear until the appointed hour, but the thought of a free shower makes up for that.
Then I have to work out how to make sure I only use 1kWh in each of the two hours. That’s easier said than done! The normal consumption 10-11 and 11-12 on a Sunday morning is about 0.1-0.2 kWh, so I have to use ~0.8 kWh before 11 and ~0.8 kWh after. That means 5½ minutes free showering each side of the hour (9kW is 0.15 kWh per minute, so 11 minutes is 1.65 kWh. The rest of the 2kWh is taken up by the 0.2 - 0.4 kWh I would normally use.)
I now have an alarm set on my phone for 10:54 tomorrow morning, giving me 30 seconds to dash into the bathroom and hop into the shower. Another goes off at 11:05 so I know to turn the shower off after another 30 seconds. Then I’ll have to wait a few hours to find out how I did by downloading my half-hourly usage data for the day so far - it’s usually a couple of hours old.
The first time I tried this technique, it failed pretty miserably. 0.623 kWh before and 1.464 after meant I’d got the quantity right (2.087 kWh in the two hours), but mistimed the start. Instead of 2kWh free, I’ll only get 1.623 kWh. At 25p/kWh, that means I miss out on 10p. Drat!
Does anyone have good ideas for maximizing the reward?
