Articles & opinion
We show our working and update conclusions when the evidence moves. Reader data, corrections and counter-arguments welcome.
A 4 kWp roof in Surrey, a 5 kWh battery and a year of half-hourly meter data.
A 2.8 kWp system was sensible in 2019. It is not now, and the reasons are not just about price.
Three differences that matter, seven that the marketing pages want you to weight.
A semi in West Yorkshire. The 14 kW survey was wrong. Here is how to tell when yours is.
The cheapest unit rate is not the cheapest tariff. Twelve months of data to show why.
The vehicle-to-home story keeps getting closer. We tally what is shipping vs slideware.