Power of good: how solar sponge tariffs can be a win for your pocket and the planet

‘Swapping conventional immersion or gas-fired hot water systems for heat pumps is probably the best option for many, especially if you can use power from rooftop solar panels.’ Photograph: Tracey Nearmy/AAP

When our ageing immersion hot water system needed replacing, I wanted to install an energy saving heat pump.

They cost more but consume far less power, and I calculated we would get the money back by trimming $270 off our annual bills. Plus we’d be doing our bit to cut greenhouse gases and reduce demand on a stressed electricity grid.