This week Caldera, the UK heat battery company, raised just £1.57 million on Crowdcube, from 1,364 investors. It was oversubscribed by 314%, having set out to raise just £500,000. It does not sell heat pumps, but instead focuses on the 15% of homes in the UK which are not connected to the gas grid – and which resort to the more expensive heat options right now of oil based central heating, typically for a larger, more poorly insulated, older home. CEO James Macnaghten, explains, “Our aim is to initially target the 3.7 million UK homes that currently use heating oil. Our heat store runs off cheap electricity, which can include solar, but is more likely to use off-peak pricing and…