Lumo’s saving calculations are based on the actual household consumption and solar generation data from a test solar & battery system over a 12 month period between 1 July 2024 and 30 June 2025.

Our test solar & battery system consists of 12 panels (5.4kWp) and a 3.6kW hybrid inverter coupled with a 10.4 kWh battery. The panels are located on a flat roof of a 3-bedroom terraced house in the East of England.

The optimised savings are estimated by running Lumo’s optimisation algorithm every hour during the 12-month period to determine when to charge or discharge a battery based on a given tariff to minimise costs.

The tariff used in this simulation is Octopus Flux, which has 3 tariff windows, namely 02:00-05:00 during which import and export prices are 15p and 5p respectively, while 16:00-19:00 import and export prices are 36p and 28p respectively. At all other times, prices are 26p and 14p respectively.

We also calculate various baselines, including no solar, solar, and solar & battery (load matching) to provide additional information and to help understand the additional savings that Lumo can unlock for homeowners.

Saving results for 2-bedroom and 4-bedroom houses have been based on scaling household consumption from the test 3-bedroom house to 2750kWh and 4,000kWh respectively, but keeping solar generation unchanged.

Lifetime savings calculations are based on annual optimised savings multiplied by 5, 10, 15, and 20 years to provide an indication of longer term savings potential but exclude the potential impact of inflation or tariff changes.

Our savings calculations are based on simulations carried out in September 2025, and are subject to change as our optimisation algorithms improve and as energy markets evolve.