National consumption has been sourced from the money week website

https://moneyweek.com/personal-finance/605440/will-energy-prices-go-down

National consumption per year.

• Gas 11,500 kWh
• Electric 2700 kWh

Using this document, we can predict the customers savings per year with the following information.

Example below

• Customers consumption is 2700 kWh per year.
• Solar PV generation of 4000 kWh per year.

Usable battery capacity (example Tesla Powerwall 12.1 to 13.1 kWh)

And “Home all day”

Solar PV only savings

The customer will save 22% of the Solar generation 880 kWh (22% of 4000 kWh) with solar PV only.
The customer give a saving of 32.6% of the customer electric bill per year for the kWh they would normally purchase per year. (32.6 % of 2700 is 880 kWh)

Solar PV and battery storage savings

The customer will save 57% of the Solar generation 2280 kWh (57% of 4000 kWh) with solar PV and a Powerwall battery installed with usable capacity of 12.1 kWh to 13.1 kWh.

This will give a saving of 84.44 % of the customer electric bill per year for the kWh they would normally purchase per year. (84.44% of 2700 kWh is 2280 kWh)

Please note standing charges are not included in these calculations and these will still have to be paid as normal.