8 kWp solar system: cost and payback
The calculator starts from an 8 kWp system in a house with a heat pump that uses about 7,433 kWh of electricity a year. The system costs about PLN 44,800, saves about PLN 3,785 a year and pays back in about 11.8 years. With lower use the payback gets noticeably longer.
Example: 8 kWp, the house uses 7,433 kWh a year
Simple payback: about 11.8 years
saves about PLN 3,785 a yearabout PLN 315 a monthcost after relief and grants about PLN 44,800
- Used straight away: 2,110 kWh, 26%
- Exported: 5,890 kWh, 74%
Power you do not buy: about PLN {avoided}. The deposit for exported energy covers about PLN {deposit} of your bills.
Cumulative balance over 25 years
After 25 years: about PLN 40,862
With degradation and upkeep the balance turns positive for good after about 13.5 years.
Electricity price from 11 October 2026, estimate
| Year | Output | Saving | Costs | Balance |
|---|---|---|---|---|
| Year 1 | 8,000 kWh | 3,785 PLN | 0 PLN | −41,015 PLN |
| Year 5 | 7,841 kWh | 3,739 PLN | 0 PLN | −25,991 PLN |
| Year 10 | 7,647 kWh | 3,681 PLN | 0 PLN | −7,469 PLN |
| Year 12 | 7,571 kWh | 3,658 PLN | 5,500 PLN | −5,641 PLN |
| Year 15 | 7,458 kWh | 3,624 PLN | 0 PLN | 5,265 PLN |
| Year 20 | 7,273 kWh | 3,566 PLN | 0 PLN | 23,209 PLN |
| Year 25 | 7,093 kWh | 3,507 PLN | 0 PLN | 40,862 PLN |
Assumptions and formulaElectricity price from 11 October 2026
output = 8 kWp × 1,000 kWh = 8,000 kWh used on site = 2,110 kWh, exported = 5,890 kWh, bought = 5,323 kWh saving = 2,110 kWh × PLN 1.04 + deposit PLN 1,590 = PLN 3,785 a year payback = PLN 44,800 ÷ PLN 3,785 = 11.8 years
- Yield per kWp
- 1,000 kWh/kWpPVGIS 5.3 (JRC): Warsaw, south roof at 35°, about 1050 kWh per kWp, 1000 to be safe
- Price per kWp
- 5,600 PLN/kWpKB.pl, solar prices 2026: PLN 5200-6300 gross per kWp
- Electricity price
- 1.04 PLN/kWhURE G11 tariffs 2026 (PGE, Tauron, Enea, Energa), average with distribution
- Value of 1 kWh exported
- 0.27 PLN/kWhPSE RCEm for April-July 2026 weighted by PV output, times 1.23
- Part of the bill the deposit covers (G11 energy)
- 0.62 PLN/kWhG11 energy prices of default suppliers, URE Masz Wybór comparison
- Deposit: multiplier and refund of unused money
- × 1.23, refund up to 30%
- House with heat pump
- 26 %KosztyDomu.pl hourly simulation on PVGIS 2020-2023 data, Warsaw, 1000 kWh/kWp
- Panel degradation
- 0.5 %/yrNREL, Photovoltaic Degradation Rates: median 0.5% a year
- Inverter replacement
- 5,500 PLNSystemy-fotowoltaika.pl: 5 kW inverter replacement with fitting PLN 5000-6000
- Thermal modernisation relief
- No relief
An estimate. Self-consumption comes from a simulation of a typical house near Warsaw, with net billing settled over a year. Fixed charges, changes in the law and battery replacement are not included. Compare at least three offers before you buy.
How electricity, gas, pellet and coal prices have changed, month by month. Price history
Ready-made calculations
How to use the calculator
- Enter your yearly electricity use from the last 12 months of bills. If you plan a heat pump or an electric car, add their use.
- Enter the system size and the price from your quote, per kWp or in total. Below the size you will see the upper limit of a sensible size for your use.
- Choose whether the house has a heat pump. The calculator then estimates self-consumption from our hourly simulation. If you know yours, set it on the slider.
- Check the electricity price and the value of exported energy, pick your thermal modernisation relief rate and add a home battery if you want one.
- Click Calculate payback. The result keeps updating as you change inputs, and you can copy a link to it.
Who 8 kWp suits
In a house with a heat pump using about 7,433 kWh, an 8 kWp system produces about 8,000 kWh and the house uses about 2,110 kWh straight away, 26%. A saving of about PLN 3,785 a year means payback in about 11.8 years, or about 10.4 years with the 12% relief.
In a house using 4,000 kWh the same system saves about PLN 3,323 and pays back in about 13.5 years. There the deposit exceeds the energy part of the bills, so the supplier refunds only about PLN 209 a year of the surplus.
Paperwork above 6.5 kW
An 8 kWp system needs design approval from a fire safety expert and a notification to the fire service. Ask your installer whether the quote includes it.
Frequently asked questions
How much does an 8 kWp solar system cost in 2026?
According to the KB.pl price review, about PLN 41,600-50,400 gross with fitting and 8% VAT. The calculator uses PLN 5,600 per kWp, which is PLN 44,800.
Does 8 kWp pay off with 4,000 kWh of use?
Less well than a smaller system. In our simulation 8 kWp then pays back in about 13.5 years and 4 kWp in about 10.8 years. A larger size makes sense when a heat pump or an electric car is coming soon.