Overview

• The study estimates about three million multi‑family buildings—some 20.4 million apartments—could host rooftop PV, adding roughly 60 GW of capacity.
• Tenant electricity costs could fall by about 2.5–5 cents per kWh, or roughly €125–€250 per year for a 5,000 kWh household, because network fees and power tax are avoided.
• Modeled returns for owners range from about 3.6% to 18.5%, with a 30 kWp system plus storage and smart metering yielding nearly €90,000 profit over 20 years in IW’s example.
• Despite the potential, only around 5,400 Mieterstrom installations are registered with the Bundesnetzagentur, compared with more than four million PV systems overall.
• IW cites complex metering and billing rules, non‑harmonized procedures across 866 distribution operators, and burdensome permitting as key barriers, while a new energy‑sharing law enables communities from June 1, 2026.