Does Plug-In Solar Work With an Economy 7 or Storage Heater?
Storage heaters and Economy 7 are common in properties without gas central heating — a lot of flats, older houses, and properties that have never been converted to gas. If you have storage heaters you already understand peak versus off-peak. Solar fits into this picture, but not in the way most people assume.
The fundamental mismatch
Economy 7 gives you cheap overnight electricity — typically midnight to 7am. Storage heaters charge up during this window from high-density ceramic bricks, then release heat gradually during the day. Your biggest electrical load runs entirely at night when solar produces nothing. Daytime solar generation offsets smaller daytime loads — the fridge, television, router, standby — not the storage heaters.
This is still useful, but the scale is smaller than with a well-matched load profile. At the Economy 7 daytime rate (typically 26p to 30p per kWh), each unit of daytime solar saves you the daytime rate, which is the more expensive part of an Economy 7 bill. Annual savings from an 800W system on Economy 7 at typical self-consumption: around £40 to £80, depending on how much daytime load there is to offset.
Does a battery help?
Potentially, with deliberate setup. Standard battery use on Octopus Go (solar charges battery by day, battery covers evening house demand) does not interact with storage heater charging at midnight. But if you have a smart battery system like the EcoFlow STREAM Pro or above, you can schedule it to charge from overnight cheap electricity and discharge during peak morning hours to supplement the fading heat output from the storage heaters. The STREAM’s scheduled grid charging function enables this.
More usefully: switching from Economy 7 to Octopus Intelligent or Octopus Go gives you a comparable cheap overnight window while adding a well-priced daytime rate and better smart tariff integration with solar. If you have storage heaters and are considering solar, a tariff review is worth doing at the same time.
For tariff comparison and how Octopus products interact with plug-in solar, see our energy tariff guide.