Solar and battery tuned to time-of-use tariff
Self-consumption increased from approximately 40% to approximately 78% after retrofit and tariff optimisation.
- Location
- Exmouth, Exeter and Devon
- Property
- 4-bed Detached
- Service
- Solar + Battery
- Date completed
- 2025
The situation
Existing 4 kW solar system generating well but exporting 60% of generation during the day. Family at work and school until 4pm. On a standard variable tariff with no time-of-use benefit.
What we designed and installed
Retrofitted a GivEnergy 9.5 kWh battery, configured for solar diversion during the day and time-of-use charging overnight after switching to Octopus Flux. Monitoring set up and Evidence Pack issued.
| Component | Specification |
|---|---|
| Solar PV | Existing 4.0 kW |
| Battery | GivEnergy (9.5 kWh) |
| Monitoring | GivEnergy monitoring |
| Tariff configured | Octopus Flux |
How we set it up
Charge windows and discharge reserve were tuned to the household profile, with export behaviour and alerts configured for predictable daily operation.
Results
Self-consumption increased from approximately 40% to approximately 78%. Saving approximately GBP1,100/year (combined solar + battery + tariff optimisation). Battery payback projected at approximately 5 years.
| Metric | Value | Basis |
|---|---|---|
| Self-consumption | Approximately 78% | Estimated |
| Annual savings | Approximately GBP1,100/year | Estimated - Octopus Flux |
| Estimated payback | Approximately 5 years | Estimated (based on current tariff rates) |
Results labelled estimated are based on system modelling and typical usage patterns. Results labelled observed are based on actual monitoring data collected after installation. Observed results may differ from estimates due to weather, usage changes, and tariff adjustments.
The installation
Customer feedback
"The retrofit changed how we use power day to day and the tariff setup finally made the numbers work."
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