BAFA innovation funding air heat pump

For example, in combination with his solar system. Even with a larger photovoltaic system, the storage can serve as an additional energy buffer if no battery is available.

ST+heat pump is a pretty suboptimal combo. Generally, a solar thermal system increases the heat generation costs (see BDEW heating cost comparison). A heat pump + photovoltaic combo is more sensible. You also don’t need the storage to store photovoltaic surpluses. These are firstly rather rare in the heating season anyway, and secondly screed (or even better capillary heating) can store additional heat much better than a normal buffer tank. Moreover, a stratified storage tank has a huge disadvantage in the case of a heat pump. Due to its construction, the heating system cannibalizes the hot water. Because of the higher hot water temperature, this is produced with a worse COP. This leads to the system having a worse overall annual performance factor. Basically, a heat pump should charge the underfloor heating directly (without a buffer). There are also corresponding studies from Fraunhofer that demonstrate this.

An alternative would have been the IDM, but I get the Kermi at a very good price. [...] We can get it, but then you need an annual performance factor calculation, right? Where can you get that from?

You can calculate the annual performance factor of the Kermi yourself. Unfortunately, the Kermi is rather mediocre and only reaches an annual performance factor of 4.24 at a supply temperature of 30°C. The other Kermi models do not seem to be better either. Not even with the reduction of the hot water portion does it reach a reasonable range. Therefore, it might be worth considering taking the more expensive IDM and then getting €2500 BAFA subsidy and thus maybe even ending up cheaper than with Kermi. The IDM iPump A2-7 reaches 4.51 at supply temperature = 30°C (which should possibly be feasible with a bathroom heating circuit), heating limit temperature = 12°C, NAT = -14°C. I personally have Nibe, but I like the IDM better... You can do the calculation yourself, but someone with the appropriate expertise has to sign it. It doesn’t even have to be your builder. There are often builders who have the relevant expertise due to their training. If necessary, you then have to prove this to BAFA.

Independently of the subsidy, wall heating in the bathroom also increases comfort. Due to the pleasant radiant heat, the air temperatures can then be around 22°C. The heat sensation is then like at 24°C air temperature.

Regards Nika

Therefore, it might be worth considering taking the more expensive IDM and then receiving 2500€ BAFA funding, which could potentially make it even cheaper than with Kermi.

2000€ is the maximum, right?

And how do you prepare fresh water then? A fresh water station needs a certain buffer from which the heat can be drawn, right?

that’s how I understand it too, but for that you would need a calculation of the system efficiency, right?

Yes and no... With air heat pumps, essentially only a system concept is subsidized...

2. Air/Water Heat Pump with Supplementary Heat Source Solar Radiation Combination of a subsidizable air/water heat pump with the supplementary heat source solar radiation. The collectors used must be eligible for subsidies according to the applicable guidelines. They must be integrated in such a way that an increase in the heat source temperature and thus an increase in the efficiency of the heat pump is achieved. The capacity of the collectors must be at least 1/3 of the standard heating load of the supplied building. The following additional conditions apply: For the used collectors, a heating capacity of 0.2 kW per m² gross collector area may be assumed.

[*]The bivalence temperature must not be above -6 °C, unless the heated building has a system for providing heat from biomass. [*]For (hybrid) heat pumps where the use of an electric heating rod is structurally excluded, the bivalence point may not exceed 0 °C. [*]A minimum system seasonal performance factor (SJAZ) of 3.9 must be demonstrated. Proof is provided by submitting a simulation calculation.

From my point of view, this system concept is technical and financial overkill. The subsidy does not even really cover the additional costs. I would rather forgo the subsidy and simply install photovoltaics. The benefit of photovoltaics on the same area is significantly higher. Additionally, photovoltaics finance themselves 100%. Photovoltaics could cover about 30% of the heat pump demand, supply other devices with electricity, and the surpluses are also compensated. Overall, it is then significantly more economical than the oversized solar thermal system from the system concept. Regards Nika

So we will probably do it that way. Either way, we are getting a photovoltaic system on the garage. The additional solar was supposed to go on the house roof.

There are only a maximum of 2000€, right?

And how do you then prepare fresh water? A fresh water station needs a certain buffer from which the heat can be drawn, doesn't it?

2000€ is correct. I was also thinking about DHW tanks. There is no 500€ combo bonus there. But as already mentioned, heat pump + DHW tank is counterproductive. Therefore, it would indeed be "only" 2000€.

Regarding fresh water station:
1. The note that a buffer is counterproductive refers to the heating buffer. For hot water, of course, a hot water buffer is needed, e.g., a "normal" domestic hot water buffer tank, a buffer tank with flow-through principle, or even a fresh water station. Which one is the most suitable depends on personal preferences and requirements. I prefer as simple solutions as possible, so rather a "normal" domestic hot water buffer.
I have explicitly not listed combination buffers, as these are efficiency killers with a heat pump.

2. Personally, I find a FWS not quite optimal with a heat pump, since heat transfer requires two heat exchangers in total. A properly sized domestic hot water storage tank would be more efficient. Nevertheless, a FWS also has advantages. There are heat pump specialists who rate the advantages of a FWS significantly higher than the disadvantages from the second heat exchanger. IMHO, everyone should decide according to their preferences/wishes/requirements. As long as the additional cost of a FWS is not too painful, from my point of view, there is nothing really speaking against it.

Regards, Nika

The additional solar should then have been installed on the house roof.

I recommend calculating the economic efficiency of the ST precisely. In general, refraining from it is more economical than installing it. Exception: high subsidy amounts. But even with high subsidies, photovoltaic systems are usually more profitable. Therefore, it might be more sensible to also install photovoltaic on the house roof, if at all... Regards Nika