Solar Battery Savings: How Much Can Storage Save You?

A solar battery saves money by shifting when you use your solar electricity. Here is the core mechanism, exactly as our battery calculator models it:

• Without a battery: roughly 45% of your solar generation is consumed directly during the day. The other 55% is exported to the grid at a low export rate — typically one-third to one-fifth of what you pay for grid electricity.
• With a battery: self-consumption rises to approximately 80%. The battery stores daytime surplus and discharges it in the evening, so you buy far less from the grid at peak rates.

The financial value of a battery equals the additional electricity you self-consume (moving from 45% to 80% of generation), multiplied by the difference between your retail electricity price and the export rate.

This is why batteries make more financial sense in countries where the gap between retail and export prices is large — and less sense where export rates are generous.

The economics vary dramatically by country. Our calculator uses these real-world rates:

Country	Retail Price	Export Rate	Price Gap	Battery Cost (typical)	Est. Battery Payback
Australia	A$0.32/kWh	A$0.05/kWh	A$0.27	A$9,450 (13.5 kWh)	7–9 years
United States	$0.16/kWh	$0.05/kWh	$0.11	$10,800 (13.5 kWh)	10–14 years
United Kingdom	£0.28/kWh	£0.15/kWh	£0.13	£6,000 (10 kWh)	9–12 years
Ireland	€0.30/kWh	€0.185/kWh	€0.115	€6,500 (10 kWh)	11–14 years
New Zealand	NZ$0.28/kWh	NZ$0.08/kWh	NZ$0.20	NZ$8,000 (10 kWh)	8–11 years
Canada	C$0.13/kWh	C$0.08/kWh	C$0.05	C$12,150 (13.5 kWh)	15+ years

Key insight: Australia has the strongest battery case (large price gap + high consumption). Canada has the weakest (small gap + cheap electricity). The UK and Ireland sit in the middle — batteries are viable but payback is longer.

Calculate battery savings for your specific situation.

Our battery calculator uses a detailed methodology to determine whether storage makes financial sense for you:

1. Daily energy split: the calculator assumes 30% of your daily electricity consumption happens during peak solar hours (10am–4pm), and 70% during evening and night. This means most of your usage happens when solar panels are not generating.
2. Direct self-consumption: without a battery, you only use solar electricity that coincides with daytime demand — about 45% of generation for a typical household.
3. Battery discharge: the battery captures daytime surplus and releases it in the evening. Round-trip efficiency is 90% (you lose 10% in the charge/discharge cycle), and depth of discharge is 90% (the battery preserves 10% of its capacity for longevity).
4. Savings comparison: the calculator computes annual savings both with and without a battery. The difference is your battery benefit. Dividing battery cost by this annual benefit gives you the standalone battery payback period.

This approach isolates the battery's financial contribution from the solar panels themselves — so you can evaluate the battery decision independently.

Our calculator recommends battery size based on your target self-sufficiency level. Here is how it works:

• No battery (baseline): ~30% self-sufficiency (direct daytime consumption only)
• Standard battery (80% target): typically 8–13.5 kWh for most homes. This covers evening usage without oversizing.
• Premium battery (90–95% target): 13.5–18 kWh. Diminishing returns — the last 10% of self-sufficiency costs disproportionately more.

The sizing formula caps battery capacity at two limits: you cannot store more than your daily surplus, and you cannot discharge more than your evening consumption. This prevents oversizing.

For a typical home with a 6 kW solar system generating ~16 kWh/day, a 10 kWh battery captures most of the usable surplus. Going to 15 kWh offers marginally more self-sufficiency but the extra 5 kWh may only be fully used in peak summer.

See how battery size affects your total savings over 25 years.

Battery payback period is calculated differently from solar panel payback. Our payback calculator handles both:

• Solar panel payback = total system cost ÷ annual savings (typically 5–9 years)
• Battery payback = battery cost ÷ additional annual savings from battery (typically 7–14 years)

The battery payback is almost always longer because:

1. The per-kWh savings from a battery are smaller than from solar panels (you are shifting usage timing, not displacing grid purchases entirely)
2. Round-trip efficiency losses (10%) reduce the effective value
3. Battery costs per kWh remain higher than solar panel costs per kW of generation

However, battery payback improves each year as electricity prices rise (at roughly 3% annually). A battery that looks marginal today may prove excellent over its 10–15 year lifespan.

Calculate your combined solar + battery payback period.

Based on our calculator data, a battery makes the strongest financial case when:

• Export rates are low — under $0.08/kWh (US, Australia). The gap between retail and export price is the battery's value driver.
• Electricity prices are high — above $0.25/kWh equivalent. Each self-consumed kWh is worth more.
• You use most electricity in the evening — the 70% evening/night consumption assumption in our calculator is typical, but households with even higher evening usage benefit more.
• You have time-of-use tariffs — charging the battery during off-peak solar hours and discharging during expensive peak evening rates maximises value.

A battery may not be worth it when:

• Export rates are generous (Ireland: €0.185/kWh — close to retail)
• Electricity is cheap (Canada: C$0.13/kWh)
• You are home during the day and already self-consume most of your solar

Not sure? Run the numbers for your specific situation. The calculator shows savings with and without a battery side by side.

If you have or plan to get an EV, the battery equation changes. Our calculator models EV integration:

• EV charging adds consumption: a typical EV driven 8,000 miles/year at 3.5 miles/kWh adds approximately 2,286 kWh annually. This is extra electricity that solar can offset.
• V2G (vehicle-to-grid): if your EV supports V2G, it acts as a secondary battery, exporting up to 5 kWh/day back to the home. This boosts self-consumption by an additional 5%, reducing the need for a dedicated home battery.
• Smart charging: charging your EV during peak solar hours (instead of overnight) dramatically increases self-consumption even without a home battery.

For households with an EV, a smaller home battery (or none at all with V2G) may be sufficient. Factor EV charging into your solar estimate using the advanced settings.

Battery prices have fallen steadily — from over $1,200/kWh in 2018 to roughly $600–$800/kWh in 2026. The question of timing comes down to:

• Case for now: you start saving immediately, electricity prices continue rising (3%+ annually), and current incentives may not last forever. Each year you wait costs you a year of potential savings.
• Case for waiting: battery costs are still falling, and newer chemistries (sodium-ion, solid-state) may offer better value within 2–3 years. Most solar systems can easily accommodate a battery retrofit.
• Best compromise: install solar now, design the system to be "battery-ready" (appropriate inverter, wiring, and space), and add the battery when prices hit your personal threshold.

Our calculator supports battery expansion planning — you can model adding a battery in a future year and see how it affects your 25-year financial projection. Try it in the advanced settings.

For current installation costs including battery, see our 2026 solar installation cost guide.