In the UK these are called "storage heaters". The efficiency is still 1:1 but you can charge them from cheap electricity sources (originally overnight electrici

In the UK these are called "storage heaters". The efficiency is still 1:1 but you can charge them from cheap electricity sources (originally overnight electricity) and have the heat released slowly over time. A unit the size of a typical wall mounted radiator (except thicker) can store over 10kWh of heat. https://www.elnur.co.uk/product/ecombi-hhr-high-heat-retention-storage-heaters/ https://www.elnur.co.uk/product/ecombi-hhr-high-heat-retenti... My parents use these as their main heat source, and once you figure out how they work, the work fine. If I was building new today I'd go with a heat pump, but they have no ducting or central heating, so retrofitting that would not be easy. These could still be useful as a supplementary heat source if you have solar, as they are much cheaper than batteries for storing energy.