The full AgNes draft determination of the Bundesnetzagentur (“BNetzA”) contains a new cost rule for so-called prosumers. It may have considerable effects on decentralised supply concepts in multi-party buildings. While communal building supply (gemeinschaftliche Gebäudeversorgung) in particular may be burdened with additional grid fees, classic tenant electricity models (Mieterstrom) may benefit from their structure. The decisive factor is whether the market locations (“MaLo”) of the individual residents remain active or are set to dormant.
New Standing-Charge Surcharge for Prosumers
For prosumers at low-voltage level with an annual offtake of up to 100,000 kilowatt hours, the draft provides, from 1 January 2029, for a surcharge of between 70 and 90 per cent of the standing charge in addition to the regular grid-fee standing charge. A minimum generation-facility size of 30 kW does not apply to this prosumer surcharge; only plug-in solar devices are excluded from the definition of a prosumer.
The draft treats a low-voltage withdrawal point as a prosumer where, in addition to electricity from the grid, electricity from a generation facility behind the same grid connection is also drawn. The BNetzA justifies the surcharge on the basis that prosumers, owing to their self-supply, draw less electricity from the grid but still require the grid infrastructure for their supply, in particular at times of low own generation.
The prosumer surcharge is also to apply to existing facilities. The draft does not provide for grandfathering comparable to the transitional arrangements for feed-in charges. Grid operators are to identify the affected prosumer withdrawal points as early as 1 April 2028 and report them to the suppliers.
Communal Building Supply Particularly Affected
The BNetzA expressly addresses multi-party buildings with tenant electricity or communal building supply. In such cases, every participating consuming market location whose grid offtake is reduced by one or more generation facilities behind the same grid connection is to be identified.
For communal building supply, this may have considerable economic effects. The participating residents retain their own residual electricity supply contract and their active market location. At the same time, their grid offtake is reduced by the building electricity allocated to them. The participating market locations therefore in principle meet the requirements of the prosumer rule. In addition to the regular standing charge, the prosumer surcharge of between 70 and 90 per cent may therefore arise for each participating resident.
Particularly for smaller electricity consumption, the additional fixed burden may considerably worsen the economics of communal building supply. The standing-charge costs grow linearly with the number of participants and work against the economies of scale that have made the model attractive to date.
A Dormant Market Location Can Privilege Tenant Electricity
Under the classic tenant electricity model, the situation may be different. Where the tenant electricity supplier takes over the full supply of the participating tenant and that tenant’s market location is set to dormant vis-à-vis the grid operator within the respective metering concept, no separate grid-fee standing charge is billed for that market location.
This is decisive for AgNes. In its reasoning, the BNetzA expressly makes clear that the prosumer surcharge is levied only where a standing charge is also billed for the market location concerned.
Setting the market location to dormant may thus become the essential advantage of the classic tenant electricity model. It does not mean that the tenant’s consumption is no longer measured or billed individually. The tenant electricity supplier may continue to bill the tenant on the basis of that tenant’s individually metered consumption. The energy-industry dormancy of the market location vis-à-vis the grid operator is to be distinguished from this.
Where no separate grid-fee standing charge is levied for the dormant market location, the scheme of the draft determination suggests that the additional prosumer surcharge does not arise for that market location either. As a result, the grid-fee standing charge and the prosumer surcharge will regularly fall due only once in a tenant electricity project — at the summation meter.
Non-Participating Tenants Remain Unaffected
Residents of a tenant electricity building who do not participate in the tenant electricity model likewise do not become prosumers merely because of the generation facility present in the building.
Anyone who draws no electricity from the generation facility and continues to be supplied entirely via an active market location by an external electricity supplier has a grid offtake that is not reduced by the local generation. Under the draft determination, however, the status of a prosumer specifically presupposes such a reduction in grid offtake.
AgNes Could Create a Competitive Advantage for Tenant Electricity
The new prosumer rule may thus lead to a remarkable shift between the two decentralised supply concepts. Participants in a communal building supply retain their active market location and may therefore in future be additionally burdened with the prosumer surcharge. Under classic tenant electricity models, by contrast, this additional standing charge can be avoided where the market locations of the participating tenants are set to dormant and no separate grid-fee standing charge arises there.
For existing and new tenant electricity projects, the specific design of the metering concept thus gains considerably in importance. Under the new AgNes scheme, setting the individual market locations to dormant may become a significant economic advantage of the classic tenant electricity model over communal building supply.
However, AgNes is so far only a draft: it remains open for consultation until 18 September 2026, the determination is scheduled for the end of 2026, and whether the unequal treatment of the two models will still be taken up in the course of the proceedings remains open.
(11 August 2026)