Solar savings calculator

Turn your electricity bill into a clearer solar starting point.

Adjust your bill, tariff, roof potential, usage and battery choice to see how each assumption changes the result.

Calculate my savings How the estimate works

Starts with your billNot an unrelated example household.

Roof-aware assumptionsCompare stronger and more limited potential.

Battery comparisonSee how greater self-use changes the value.

No hidden guaranteeThe survey and written proposal confirm the design.

Build your illustration

Change the assumptions. See the result respond.

The calculator separates the electricity used in the home from the electricity exported, so the estimate does not rely on one blanket saving percentage.

01Your electricity

Average monthly electricity bill

Electricity import rate

p/kWh

Use the unit rate from a recent bill where possible. Standing charges are not changed by solar and are not included in the calculated saving.

02Possible solar system

3.6 kWpSmaller roof4.8 kWpTypical home6.0 kWpHigher demand8.0 kWpLarger property

Roof and daylight potential

03How the home uses energy

Lower daytime useMost demand is in the eveningBalanced useSomebody is often homeHigher daytime useHome working, EV or heat pump

Include battery storageModel a greater share of solar being kept for later use.

Advanced assumption

Export payment

p/kWh

This is editable because export tariffs vary by supplier and eligibility. Enter 0 if you do not want export income included.

How the estimate works

Four parts shape the result.

The calculator keeps the assumptions visible so the result can be understood and challenged rather than presented as a mysterious headline figure.

Estimate annual use

Your annual spend and import unit rate provide a starting estimate of how much electricity the property currently buys.

Estimate generation

System size is multiplied by the selected roof-potential assumption to illustrate annual solar generation.

Separate use and export

Electricity used in the property is valued at the import rate. Spare generation is valued at the entered export rate.

Show the direction

The 25-year figure holds current rates steady and applies a small output reduction. It is not a forecast of future tariffs.

What the calculator cannot see

The roof still decides the real design.

Satellite imagery, site measurements and electricity information help REST move from a broad illustration to a system that can actually be installed.

Usable roof areaObstructions, setbacks and suitable fixing zones.

Shade and orientationHow the array is likely to perform throughout the year.

Electrical routeInverter, battery, consumer unit and cable locations.

Future demandEV charging, heat pumps and changing household use.

Questions

Solar savings estimates, explained clearly.

Is this savings estimate guaranteed?

No. It is an illustration based on the figures and assumptions entered. A final proposal depends on the property survey, roof layout, shading, electrical arrangement, tariff, household behaviour, equipment and agreed system design.

Why does the calculator ask for my electricity unit rate?

Does adding a battery always create a better financial result?

Does the result include installation cost, finance or payback?

Is export income included?

How can REST make the estimate more accurate?

Turn the estimate into a real design

Ask REST to check the roof behind the numbers.

Share the estimate with the team and REST can review the property, usage and practical system options before preparing a clearer recommendation.