The vocabulary, the units and the bills. The things everything else on the site assumes you already know.
Energy prices only go up, the argument runs, so panels and a heat pump protect you against inflation. This article checks that against what electricity, gas and savings accounts did from 2016 to 2025, for one solar roof and one heat pump.
Panels, inverters, heat pumps, batteries and cylinders all have different lifespans. Knowing which is which stops a normal replacement feeling like a failure.
Three numbers on your bill do all the work, and finding them takes about five minutes. They are also the numbers every calculator here asks for.
Bills, quotations and savings on this site are all counted in kilowatt-hours. What one is, and how to find out how many your house gets through.