Solar panels: how much power your roof will give
Pick your municipality, system size and roof direction. The table below the result gives the output for every tilt and direction.
Yearly saving on your bills
PLN 3,425
6,300 kWh produced · 27 % used on site
| Used directly and from the battery | 1,698 kWh |
| Exported to the grid | 4,603 kWh |
| Deposit (×1.23) | PLN 1,569 |
| Deposit spent on energy | PLN 1,408 |
| Overpayment refunded | PLN 162 |
| Bill before / after | PLN 4,373 / PLN 1,110 |
| Pays back in 10 years up to | PLN 34,253 |
Hourly model of an average day in each month; surplus priced at the last 12 months of RCEm (PSE) plus the gain from negative RCE counted as zero. An estimate, not an offer; fixed charges excluded.
| Tilt | south | south-east | south-west | east | west |
|---|---|---|---|---|---|
| 10° | 5,724 | 5,591 | 5,569 | 5,242 | 5,210 |
| 20° | 6,055 | 5,823 | 5,770 | 5,182 | 5,107 |
| 30° | 6,252 | 5,950 | 5,868 | 5,086 | 4,972 |
| 35° | 6,300 | 5,968 | 5,870 | 5,020 | 4,893 |
| 40° | 6,312 | 5,960 | 5,848 | 4,936 | 4,797 |
| 45° | 6,287 | 5,923 | 5,801 | 4,836 | 4,694 |
A solar panel turns light into direct current, and an inverter turns that into the alternating current a house uses. How much energy the whole roof gives depends on three things: sunshine in the municipality, the direction of the roof and its tilt, and only then on the panel brand. According to PVGIS, 1 kWp on a 35° south-facing roof produces between 925 and 1,114 kWh a year in Poland. In Warsaw a 6 kWp system facing south produces about 6,300 kWh, and facing east or west about 4,893 kWh, which is 22 % less. An east-west roof is therefore no obstacle, and under net-billing it can even help, because it spreads output over the morning and afternoon, when the house uses more. The calculator above works out the output for your municipality, size, roof direction and tilt.
Checked by Radif Partners · Editorial policy · Method
Direction and tilt: 6 kWp output in Warsaw
The table shows the yearly output of the same system set up in different ways. Eastern directions give almost the same as western ones, so they are not repeated. Values come from PVGIS, with the monthly profile of the Mazowieckie region and 14% system losses.
| Tilt | south | south-west | west |
|---|---|---|---|
| 10° | 5,724 kWh | 5,569 kWh | 5,210 kWh |
| 20° | 6,055 kWh | 5,770 kWh | 5,107 kWh |
| 35° | 6,300 kWh | 5,870 kWh | 4,893 kWh |
| 45° | 6,287 kWh | 5,801 kWh | 4,694 kWh |
What matters more than the panel brand
The efficiency gap between common monocrystalline panels is now 1–2 percentage points, and it mainly means less roof area, not more kilowatt-hours from the same power. Shade changes far more: a chimney or tree covering one panel in a string can cut the output of the whole string. On a shaded roof, ask the installer about optimisers or micro-inverters.
The second thing is matching size to consumption. Since April 2022 surplus goes into net-billing and is valued at the market price, so a system twice as large as you need does not save twice as much. The pages on 4 kW, 6 kW and 8 kW show what size your house needs, and solar panel cost covers the price.
You can check the calculator’s figure in the PVGIS tool by entering the coordinates of your own roof. You will get the same number to within a few per cent, because we calculate for the centre of the municipality.