Solar panels in Cologne

Modelled output of a 6 kWp system at 35° facing south (towards the equator), from PVGIS climate data (PVGIS-SARAH3, 2005 to 2023).

• Best month: June (730 kWh). Weakest: December (183 kWh), a 4x difference.
• May, June, July produce 36.1% of the year; January, November, December produce 10.8%.
• Year-to-year variation: about 316 kWh (5.3%, one standard deviation).
• Sunlight reaching the panels: 1,301 kWh per m² a year.

Rules set by the city or its region, on top of the national scheme. Each one was checked against the official source on the date shown.

• North Rhine-Westphalia

  NRW solar mandate for new homes and full roof renewals

  In North Rhine-Westphalia, new residential buildings whose building application was filed after 1 January 2025 must carry a PV system, and the obligation also covers buildings whose roof covering is fully renewed with work starting after 1 January 2026. New builds must cover at least 30 percent of the gross roof area; for homes with at most two dwellings the regulation allows at least 3 kWp as an alternative minimum size.

  Source: Land Nordrhein-Westfalen (RECHT.NRW.DE), Solaranlagen-Verordnung Nordrhein-Westfalen (SAN-VO NRW) (checked 2026-09-25)

• City of Cologne

  Cologne grant for PV, batteries and plug-in solar

  The City of Cologne pays flat grants for PV on existing residential buildings (completed at least five years before the application): 1,500 euros for 2 to 5 kWp, rising to 2,500 euros above 14 kWp, plus 500 to 1,300 euros for battery storage, limited to 60 percent of eligible costs. Plug-in solar devices receive 150 euros per dwelling.

  Source: Stadt Köln, Förderprogramm Photovoltaik: klimafreundliches Wohnen in Köln (checked 2026-09-25)

Cologne ranks 3 of 4 for yield among the cities we model in Germany, and 33 of 41 across every country on Solar Figures. Within one country the prices are the same, so a payback gap between these cities comes from sunshine alone.

Closest yield abroad: Antwerp (1,005 kWh per kWp), Rotterdam (1,000 kWh per kWp), Brussels (1,009 kWh per kWp).

Power you use yourself is worth the retail price (€0.37 per kWh); power you export earns €0.078. So the share you use at home, by running appliances in daylight or adding a battery, changes the payback. The system cost stays the same in every row (a battery would add to it).

• Net system cost after incentives: €7,800 for 6 kWp.
• Incentive modelled: 0% VAT (Nullsteuersatz), embedded in net cost.
• 25-year net savings at our default: €24,970.

At latitude 50.94°N, PVGIS finds the fixed tilt and direction that maximise yearly output. Our figures use a common 35° roof; the table shows what the optimum adds.

The optimum adds 0.2% a year over the standard roof in Cologne. Most of a roof's value comes from its direction: a roof facing away from the equator loses far more than a few degrees of tilt.