Octopus Cosy is better for us than Octopus Go (with a heat pump and EV, but no home solar or battery)
This is our air source heat pump install week. More on that another time, but one of the choices we have to make is what energy tariff to switch to.
This is problematic as we have an EV tariff called “Go” that gives us 8.5p kWh at night and we have trained ourselves to shift energy into that time slot. Moving away from 8.5p is emotionally challenging.
The alternative on offer from our energy supplier, Octopus, is called “Cosy” which has blocks of ~13p kWh energy during the day and late evening, and a punishing ~40p rate during peak early evening.
How to compare these options? I have three useful sources of information:
- Our home EV charger gives us how much energy we put into the car at home each year. It’s about 1,400 kWh which amounts to ~£120/year.
- Our current home energy usage from our bills: 10,200 kWh over the last 12 months.
- The EPC (energy performance certificate) generated as part of the heat pump pre-install. This estimates the home energy usage with the heat pump will be 3,767 kWh.
A couple of things: wow, charging our car at home is cheap; and wow again, that’s a huge drop on energy use when switching from gas to a heat pump.
My conclusions from twiddling with these numbers: even allowing for time shifting hot water heating into the Go cheap rate, it’s better for us to switch to Cosy.
The car charging goes up from £120 year to £185, but the heating cost dominates and we end up saving just under £300 year by switching. Which is exactly what Octopus estimated, almost like they know what they are talking about.
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Here’s our referral link for Octopus which gives you £100, and us £100 in energy credits. If you’re not using Octopus, I’m told Heat Geek are very good.