ᐅ Photovoltaic system or geothermal heating

Hello,
The building is a multi-family house with 4 residential units.
KfW 55 standard is achieved through the building envelope and an air-to-water heat pump.
Additionally, a controlled ventilation system is planned for each unit, but this is not a strict requirement.

The question is:
- Should we stick with the air-to-water heat pump and also install a photovoltaic system for electricity generation,
- Or should we forgo that and use geothermal energy via deep drilling for heating?

What do you think makes more sense in terms of cost and/or KfW subsidy eligibility?

None of the additional measures will improve the KfW standard if 55 is already achieved.

If you want to use photovoltaic panels, my question would be about the intended use. Should the system feed all the electricity back into the grid, or should the electricity be sold to the tenants? Are you aware of the associated effort?

In principle, a photovoltaic system could generate a return in both scenarios.

Geothermal energy ultimately reduces the tenants’ consumption costs or operating expenses. You would need to recover the additional investment through higher base rent.

I wouldn’t do anything at all.

Hello,
for a purely rental property, I would not even have considered KfW 55, but rather stuck with the standard Energy Saving Ordinance or KfW 70.

Best regards.