In short
- Paid back in
- 10.8–26.1 years 20 panels facing south in 20 cities.
- Net over 25 years
- −5 670 kr–172 180 kr The lowest and the highest of the cities.
- Solar per kW
- 880–1,035 kWh Per kW of panels a year, facing south.
The slope matters most
We calculated the same house in Stockholm with 20 panels and no battery.
Only the direction and the slope of the roof change. It is the same calculation as on our city pages.
- 1.0°: facing north 808 kWh/kWp, facing south 823 kWh/kWp
- 5.0°: facing north 777 kWh/kWp, facing south 851 kWh/kWp
- 10.0°: facing north 737 kWh/kWp, facing south 881 kWh/kWp
- 20.0°: facing north 654 kWh/kWp, facing south 929 kWh/kWp
- 27.0°: facing north 595 kWh/kWp, facing south 950 kWh/kWp
- 35.0°: facing north 530 kWh/kWp, facing south 964 kWh/kWp
- 45.0°: facing north 457 kWh/kWp, facing south 962 kWh/kWp
At a low slope, the difference is small. The steeper the roof, the larger it gets. At 45.0°, the north roof gives less than half of what a south roof gives.
Why a steep north roof gives less
In Sweden the sun is in the south at midday.
A steep roof facing north leans away from the sun. The panels then get mostly light from the sky and little direct sun.
A flat roof does not lean away from any side. It gets sun all day, whatever its direction. So the direction hardly matters when the roof is almost flat.
An almost flat north roof works
With 20 panels on a 1.0° roof facing north, the house gets 6 790 kWh a year.
It saves 8 145 kr a year. The system has paid for itself after 16.2 years.
A 27.0° roof facing south gives 7 984 kWh a year. It saves 9 484 kr a year and has paid for itself after 13.9 years. So the flat north roof gives a bit less, but it works.
Racks facing south on a flat north roof
On a flat roof, you can put the panels on racks that lean toward the south.
We calculated racks at 10.0° and 15.0° on a 1.0° roof facing north. The calculation includes the space between the rows and the shade from the row in front.
With racks at 15.0°, the roof gives 898 kWh/kWp a year. That is 7 539 kWh. The house saves 8 954 kr a year and the system has paid for itself after 14.7 years. That is almost as much as a roof facing south.
With racks at 10.0°, the roof gives 877 kWh/kWp. That is 7 363 kWh, and it saves 8 767 kr a year. It takes 15.1 years before the system has paid for itself.
Racks need space between the rows. On our roof, 80 panels fit flat on the roof, but only 50 on racks. For 20 panels, the roof is still large enough.
Our calculation uses the same price with and without racks. Racks cost more, so in real life it takes a bit longer before they have paid for themselves.
Malmö and Luleå
In Malmö, a 1.0° roof facing north gives 897 kWh/kWp.
A 27.0° roof facing south gives 1 035 kWh/kWp. With racks at 15.0°, the flat north roof gives 986 kWh/kWp and has paid for itself after 11.3 years.
In Luleå, a 1.0° roof facing north gives 749 kWh/kWp. It takes 30.5 years before it has paid for itself. A 27.0° roof facing south gives 895 kWh/kWp and has paid for itself after 26.1 years. With racks at 15.0°, it is 841 kWh/kWp and 27.6 years. So in the north it takes a long time, whatever the direction.
Check your own roof
Your roof has its own slope, direction and shade.
Enter your address and we calculate your own roof, also if it faces north.
20 cities: 20 panels facing south
| City | Paid back in | Net over 25 years | Solar per kW |
|---|---|---|---|
| Malmö | 10.8 years | 172 180 kr | 1,035 kWh |
| Lund | 11.9 years | 144 755 kr | 998 kWh |
| Växjö | 11.9 years | 145 305 kr | 921 kWh |
| Västerås | 12.4 years | 134 155 kr | 926 kWh |
| Helsingborg | 12.5 years | 132 430 kr | 953 kWh |
| Uppsala | 13.0 years | 122 680 kr | 928 kWh |
| Norrköping | 13.2 years | 118 630 kr | 948 kWh |
| Halmstad | 13.2 years | 117 455 kr | 934 kWh |
| Örebro | 13.5 years | 113 230 kr | 933 kWh |
| Göteborg | 13.9 years | 105 030 kr | 937 kWh |
| Jönköping | 13.9 years | 104 580 kr | 910 kWh |
| Eskilstuna | 13.9 years | 104 805 kr | 924 kWh |
| Stockholm | 14.0 years | 104 455 kr | 950 kWh |
| Linköping | 14.7 years | 92 605 kr | 945 kWh |
| Karlstad | 15.1 years | 86 280 kr | 948 kWh |
| Gävle | 15.3 years | 83 205 kr | 914 kWh |
| Borås | 15.4 years | 82 505 kr | 880 kWh |
| Sundsvall | 18.0 years | 51 255 kr | 891 kWh |
| Umeå | 20.9 years | 25 880 kr | 881 kWh |
| Luleå | 26.1 years | −5 670 kr | 895 kWh |
A worked example for one city is on the page about Stockholm.
Questions and answers
Can you put solar panels on a north-facing roof?
Yes. An almost flat north roof gives almost as much as a roof facing south. In Stockholm, a 1.0° roof facing north gives 808 kWh/kWp a year.
Do racks pay off on a flat north roof?
Racks at 15.0° give 898 kWh/kWp in Stockholm. But the racks cost more, and fewer panels fit on the roof.
How steep can a north roof be?
The steeper the roof, the less power it gives. At 45.0°, a north roof in Stockholm gives 457 kWh/kWp a year.
How we made this article
- Date of the numbers
- 2026-11-10
- Calculation
- Calculation engine v2, PVGIS weather (Oct 2026), example installer prices v9
- Text
- An AI model drafted the text from our data. A person at Numsolar checked and approved it before publishing.
- Grid fee
- Växjö: a typical grid fee, because Växjö Energi’s fee follows the spot price and the calculation cannot model that. Malmö, Örebro, Norrköping: a typical grid fee, because we have not been able to read E.ON’s price list.