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A SMALL SPACE. A LITTLE SUNSHINE.

Balcony solar
payback calculator.

Know your numbers before you buy. Estimate savings using your costs, net annual generation and electricity prices. See what a battery really adds.

Calculate your paybackSee how it works
Free to useNo account neededYour inputs stay here

Calculate your balcony solar payback

Start with the example, then make it yours.

Build your scenario

1Your solar
kWh / yr

Use measured output or a PVGIS / PVWatts estimate for your actual panel position. Losses already included.

total

Include panels, mounting, inverter and installation, after any confirmed upfront grant.

2Your electricity
/ kWh
/ kWh

Enter 0 for export if you receive no payment. Currency changes labels, not your prices.

40%
NoneAll generation

Share of solar used as it is generated. This is your assumption, not a share of your electricity bill.

Battery comparison
total
60%
NoneAll surplus

Assumed share of remaining solar sent into a battery. Only include energy your system can store and later use.

%
years
Longer-term assumptions
years
%
/ year

Battery replacements use its initial cost, at the end of each battery life. No replacement is bought at the period’s endpoint. Energy prices and other costs stay constant.

The starting values are an editable example, not local prices or a generation forecast. Your inputs stay in this browser.

Your solar, on paper

Estimated first-year savings

£95/ year

850 kWh generated · 340 kWh used at home in year one.

Whole-system payback
6.9 yrs

Estimated year-end balance stays nonnegative through year 20.

20-year net savings
£1,166

After modeled costs. Undiscounted.

Based on your assumptions. Compare the lower-generation case before deciding.

Solar only

£95 / year

Upfront: £650

Solar + battery

£172 / year

Upfront: £1,450

Battery adds £77 in first-year energy value, before its extra purchase and replacement costs.

Your cash flow over time

Example cumulative solar cash flow over 20 yearsSolar only ends at £1,166 and with battery at £1,037. These are editable example assumptions.

View annual cash flow
Cumulative net savings at the end of each year
YearSolar onlyWith batteryBattery replacement
0-£650-£1,450—
1-£555-£1,278—
2-£460-£1,106—
3-£366-£936—
4-£272-£766—
5-£179-£597—
6-£86-£429—
7£6-£262—
8£98-£95—
9£190£70—
10£281-£565£800
11£371-£401—
12£462-£238—
13£551-£76—
14£640£86—
15£729£246—
16£817£406—
17£905£565—
18£993£723—
19£1,080£881—
20£1,166£1,037—

Leave room for cloudy days

Compare lower and higher solar generation

Compare 20% less generation, your starting estimate and 20% more. Prices, direct-use share and storage capture stay the same. These are illustrative scenarios, not probability ranges.

Lower output−20% sun

£76

First-year savings

8.7 yrs to break even

680 kWh / year

Your estimateBase case

£95

First-year savings

6.9 yrs to break even

850 kWh / year

Higher output+20% sun

£114

First-year savings

5.8 yrs to break even

1020 kWh / year

Small solar. The full picture.

A useful estimate looks beyond how much electricity a panel can generate.

Your real electricity prices

Directly used energy avoids imports. Surplus earns only the export payment you enter.

The battery difference

Compare the extra value of storage with its cost, efficiency losses and replacement.

More than a payback date

See the full cash flow, including output decline, upkeep and the lower-generation scenario.

A transparent estimate

How we calculate solar savings and payback

A useful estimate shows its working. Here is what your numbers mean, and where this simple model stops.

Annual value = avoided electricity purchases
+ export income − annual upkeep
01

Start with electricity you actually generate.

Enter first-year net AC generation from readings or a PVGIS estimate. Your location, mounting angle and nearby shade matter. We do not deduct system losses a second time.

02

Give each kWh the right value.

Directly used solar avoids your import price. Surplus earns only the export payment you enter. Storage returns the captured surplus multiplied by efficiency; that energy loses its original export income. See SAM battery metrics.

03

Follow the money through the whole period.

Cash flow starts with the installed cost. Each year adds net energy value and deducts battery replacements. PV output declines at your chosen rate. Our payback uses the last interpolated crossing above zero, so modeled replacements are included.

All assumptions & limitations
  • Direct use and storage capture are user assumptions. Annual totals do not verify battery capacity, power limits, seasonal timing or household demand. Assume all delivered battery energy offsets electricity you would otherwise buy.
  • Payback is for the selected whole system, not the battery alone. It means the estimated balance remains nonnegative at year-end through the selected period. Fractional years are interpolated. This differs from first-crossing simple payback.
  • Battery life triggers replacements at the initial battery cost. There is no replacement at the period’s endpoint. Intermediate battery capacity fade and additional standby use are not simulated.
  • PV output falls by the entered compounded annual rate. Electricity prices and upkeep stay constant. No financing, taxes, discounting, residual value, grid charging or time-of-use trading is included. Other replacements require a separate allowance.
  • Direct savings include avoided variable import charges, export income and upkeep; fixed grid charges remain. Export payment defaults to zero. Only enter income you actually qualify for.
  • All starting costs, output and percentages are examples. Currency changes formatting only. Calculator inputs stay on this device. Optional visitor analytics are controlled through Analytics preferences.
  • Method sources: JRC PVGIS, SAM cash-flow payback, Energy Saving Trust storage guide. Reviewed 30 October 2026.

Before you buy balcony solar

Three practical guides to help you bring better numbers to the calculation.

01 / FIELD NOTES

Is balcony solar worth it?

Estimate whether balcony solar fits your home using installed cost, usable generation, electricity prices and realistic self-consumption.

Read the guide02 / FIELD NOTES

Do you need a battery for balcony solar?

Compare the extra cost of a solar battery with its incremental savings, including round-trip losses and foregone export income.

Read the guide03 / FIELD NOTES

How to estimate solar generation

Find a realistic annual solar generation estimate for your location, tilt and shading, and avoid counting system losses twice.

Read the guide

Balcony solar payback questions

Clear assumptions make for a clearer decision.

Does this work for my country?

The calculation uses your own generation, costs and electricity prices, with no assumed national subsidy or export scheme. Select a currency and enter every price in that currency. Check local installation requirements separately.

Do I need a battery to save money?

No. Solar used directly can avoid grid purchases without storage. A battery adds value only to the extent it can shift unused solar to later demand, after losses and costs. Compare both scenarios rather than assuming storage is always better.

Why can a battery make payback longer?

The battery adds upfront and replacement costs. Its extra energy value may not cover those costs, especially when direct use is already high or exported solar earns a good payment.

Is this an installation quote or a generation forecast?

It is a financial scenario based on the numbers you enter. It does not inspect your balcony, calculate local shading or confirm connection eligibility. Use measured generation or a suitable production model and include your actual installed costs.

YOUR NEXT STEP

Let your numbers
do the talking.

Try the example, compare both setups, then see what changes with your own costs.

Use the balcony solar payback calculator