What a Year of Solar and Batteries Really Saved Us in 2025

A detailed analysis of one year's worth of data from a home solar and battery installation in the UK shows significant cost savings. The setup includes 14 solar panels (4.2kWp), 3 Tesla Powerwall 2 batteries, and a smart tariff from Octopus Energy. By load-shifting electricity usage from peak (£0.28/kWh) to off-peak (£0.07/kWh) rates and exporting excess energy at £0.15/kWh, the household reduced their effective electricity rate to £0.03/kWh. Total annual electricity costs dropped from an estimated £3,633 to £557, saving £3,078. The £39,360 installation is projected to pay for itself in approximately 11 years, representing a 9% annual return on investment. The system also provided backup power during outages.