Zero consumption regulation for combined heat and power plant - Costs?

Our developer is constructing a combined heat and power plant for our three-party condominium owners' association, which uses the generated electricity entirely for the common areas; the surplus is fed directly into the power grid and compensated accordingly by the operator.

Unfortunately, it is currently not planned for the owners to use the generated electricity themselves.

Is it possible to retrofit something like this and, if so, what costs should be roughly expected?

Who is the operator? I imagine it is tax-wise complicated.

The combined heat and power plant is operated by the owners; by operator I meant the electricity grid provider, who then compensates accordingly.

In general, something like this is possible and is then called your tenant electricity model. The problem with the matter: The operator of the combined heat and power plant, i.e. the community of owners, thereby becomes the electricity supplier for the 3 parties and must assume certain obligations or outsource them externally. This particularly includes billing. Each party needs its own load profile meter in order to correctly allocate the electricity quantities. It may be possible to work with a normal meter if it is ensured that only quantities from the combined heat and power plant run through it and no electricity from the general power grid.

Are you really the operator of the combined heat and power plant as owners? You are certainly looking for a company that takes care of maintenance and servicing. How about gas procurement? Even without self-supply, combined heat and power plants are subject to a not insignificant number of notifications to, for example, the BAFA and the grid operator. Does a service provider take care of that?

With 3 residential units, it will probably be a combined heat and power plant with 5-10 kW electrical output. Whether that really makes sense (also, for example, due to noise emissions), I do not want to judge.