Does rooftop solar on an apartment block pay off – and who benefits?

The short answer

Solar power on an apartment block pays off in most cases – just not equally for everyone. Who in the building benefits depends on the chosen model: tenant power (Mieterstrom, § 42a EnWG) with a subsidy and full supply, communal building supply (gemeinschaftliche Gebäudeversorgung, § 42b EnWG) without the subsidy but far leaner, or individual tenants’ own balcony solar units.

The large pot of funding many hope for is in fact small: the tenant-power subsidy sits between 2.51 and 1.57 cents per kilowatt-hour in 2026, and only on the electricity genuinely delivered to residents. The system earns its money through the power it sells and the power it feeds in – the subsidy is a top-up, not the business.

Tenant power, communal building supply or balcony solar – what is the difference?

Since the Solarpaket I of 2024, there are three clean routes for solar power in a multi-party building. They differ in who supplies, who is responsible for the remaining electricity, and whether there is EEG funding.

	Tenant power (§ 42a EnWG)	Communal building supply (§ 42b EnWG)	Balcony solar
Who operates	landlord or service provider	landlord, service provider or the owners’ association	individual household
Remaining electricity	comes from the tenant-power supplier (full supply)	stays with each resident’s own supplier	stays with the resident’s own supplier
Tenant-power subsidy	yes	no	no
Price cap for tenants	at most 90% of the basic-supply tariff	freely agreed in the building-supply contract	not applicable
Effort	high (supplier with all obligations)	medium (quarter-hourly metering, allocation key)	low (registration in the Marktstammdatenregister)

The decisive sentence from the Bundesnetzagentur is unambiguous: communal building supply “expressly excludes the use of the EEG tenant-power subsidy”. In return, the full-supply obligation falls away – and with it most of the bureaucracy on which classic tenant-power projects often founder.

What does the tenant-power subsidy deliver in 2026?

The subsidy under § 21 of the Renewable Energy Sources Act is paid on a sliding scale by system size, and the commissioning date decides the rate. For systems connected to the grid between 1 August and 31 December 2026, the Bundesnetzagentur states:

System segment	Tenant-power subsidy
up to 10 kW	2.51 ct/kWh
up to 40 kW	2.33 ct/kWh
up to 1,000 kW	1.57 ct/kWh

The reference point matters: the subsidy flows only for the kilowatt-hours actually delivered to residents – not for the entire output. The surplus that goes into the grid is remunerated through the feed-in tariff, as with any other rooftop system. The subsidy is therefore a premium on self-consumption, not a basic income for the roof.

What actually pays off on an apartment block?

A worked example makes the orders of magnitude tangible. Suppose a building with twelve residential units gets a 60-kilowatt rooftop system. At around 950 kilowatt-hours of yield per kilowatt, it generates roughly 57,000 kilowatt-hours a year. The following assumptions are disclosed and deliberately conservative: without a battery, around 30 per cent goes directly to residents, the rest into the grid.

Item	Quantity / rate	Amount per year
Total generation	~57,000 kWh	–
Direct delivery to tenants (assumed 30%)	~17,000 kWh	–
Tenant-power subsidy (tiered, 60 kWp ≈ 2.1 ct)	17,000 kWh	~€360
Grid feed-in of surplus (~70%)	~40,000 kWh	–
Partial feed-in tariff (60 kWp ≈ 6.4 ct)	40,000 kWh	~€2,560
Tenants’ savings (price cap, ~3–4 ct/kWh cheaper)	17,000 kWh	~€600

The figures show the honest order of the levers: the biggest item is the feed-in, then the power sold to residents, and the subsidy is the smallest wheel. The feed-in figure is an applicable rate for a 60-kilowatt system as a weighted average; the exact level depends on the commissioning month. Anyone who lifts self-consumption to 40 to 60 per cent with a battery shifts revenue from the feed-in into the higher-value self-consumption – that is the real profitability lever, not the subsidy.

Which model is worth it for whom?

Tenant power fits when the operator wants to act as a full supplier anyway and residents are to receive a closed offer with a capped price – the subsidy is then a bonus. Communal building supply is the pragmatic route for owners’ associations and for landlords who do not want to be responsible for the remaining electricity: fewer obligations, but no subsidy. Balcony solar is the solution for the individual household that does not want to wait for a landlord’s decision.

From my work on financing models in energy supply, I see the most common mistake as choosing the model by the funding. The correct order is the reverse: first clarify who in the building is to use the power and how much bureaucracy you are willing to carry – the funding is a consequence, not a reason.

What can tenants do without their landlord?

Anyone who cannot or does not want to wait for a building system has had their own option since the Solarpaket I. A balcony solar unit with up to 800 volt-amperes at the inverter no longer has to be reported to the network operator; the simplified registration in the Marktstammdatenregister is enough. It mainly covers the base load of your own flat – fridge, router, standby – and lowers your own electricity bill without the building community having to be involved.

What to do now

1. Check the roof: orientation, structural capacity and available area determine how large the system can sensibly be.
2. Estimate consumption in the building: the higher the simultaneous consumption of residents, the more direct delivery pays off over feed-in.
3. Choose the model: tenant power where full supply is wanted, communal building supply where lean effort matters – do not decide by the subsidy.
4. Run the numbers: set the feed-in tariff, sales revenue and subsidy against the current Bundesnetzagentur rates for the planned commissioning month.
5. Cost out storage: a battery lifts self-consumption and thereby the economically decisive share.
6. Draft the contracts cleanly: settle the price cap for tenant power, the allocation key for building supply and the quarter-hourly metering early.