Mathias ReißenweberThe Green Consulting

Use case

Tenant electricity and PV in apartment buildings

Supplying solar power from the building’s own roof directly to tenants and owners in Germany. I support landlords, housing companies and owners’ associations from comparing the models to day-to-day operation.

Starting point

An apartment building has a free roof, but all electricity still comes from the grid. The landlord or owners’ association wants to use solar power directly in the building but is wary of the effort, metering and legal questions.

Two models, two levels of effort

§ 42a EnWG

Tenant electricity (Mieterstrom)

The landlord or a service provider supplies the solar power plus residual grid power as a full supply. The price may not exceed 90 % of the local default tariff, and the EEG tenant electricity premium may apply. In return, the obligations of an electricity supplier apply.

§ 42b EnWG

Shared building supply

Solar power is allocated to participating apartments using a fixed key. Residents continue to buy residual power from their own supplier. Far fewer obligations and simpler billing, but no tenant electricity premium.

Which model fits depends on building size, resident structure, consumption and how much effort you want to put into billing and customer service. I calculate this in advance for your property.

How it works

  1. Survey Roof and structure, grid connection, meter spaces and consumption of apartments and common areas.
  2. Model and economics Tenant electricity or shared supply, system size, storage, pricing and returns compared.
  3. Metering concept and grid operator Meter cabinet, summation or virtual metering concept, smart meters, registration and coordination with the grid operator.
  4. Contracts and billing Supply or usage contracts separate from the lease, selection of a billing service provider, informing residents.
  5. Construction and operation Tendering, site supervision, commissioning and monitoring, optionally combined with heat pumps and EV charging.

Example scenario

Apartment building with twelve flats plus common areas, meter cabinet in the basement from the 1990s. First I check the roof, grid connection and space in the meter cabinet. Then I calculate both models: tenant electricity with full supply and premium versus shared building supply with lean billing. For the chosen model I agree the metering concept with the grid operator, tender the system and meter conversion and support commissioning through to the first bill.

What you get

  • Model comparison with profitability calculation
  • Metering concept agreed with the grid operator
  • Tender documents and bid comparison
  • Implementation roadmap with dates and responsibilities

Why electrical know-how is decisive here

Whether a tenant electricity project works is often decided in the meter cabinet: metering concept, space requirements, conversion of meter spaces and the grid operator’s approval. That is exactly where my focus lies.

Note: the legal framework for tenant electricity in Germany is adjusted regularly. I check the current status for every project.