Additional heating with air-to-water heat pump and "solar power plant"?

Hello everyone,

after we had long focused on a gas condensing boiler and ventilation system, we are now reconsidering whether another heating system might be the better choice.
The additional costs for an air-water heat pump are lower with the standard included underfloor heating and ventilation system at a house provider than the price for gas condensing boiler + underfloor heating + ventilation system + gas line. So far so good.
Now we would like to discuss this scenario again with our current favorite Okal Haus. With that, we would additionally consider the "solarkraftwerk" = photovoltaic system with storage system.
My question now is: with a combination of air-water heat pump, ventilation system with heat recovery, and the solarkraftwerk—do you actually have to heat with electricity at some point? We live in the Rhine region—the temperatures here are the mildest in Germany—with temperatures below 15 degrees rarely expected—if at all.
The house will be a simple single-family home with 1.5 floors and approx. 150 m². We currently live as two...

Thank you very much for your help—additional tips that could make the choice easier are also welcome...

Regards
Jeanette

Heating with electricity? Whether your heating element on the air-water heat pump kicks in depends on the outside temperature. To keep the entire system running, including the ventilation system and heat recovery, you need operating power. If your photovoltaic system generates little electricity in winter due to clouds / fog / darkness and your storage is empty, you will have to purchase electricity for the heating system! Depending on the size of the storage and the photovoltaic system, it can also run completely independently,...

I would rather combine solar thermal energy if anything; it is not, like solar power, solely dependent on solar energy but also works with ambient heat from the air, for example (of course not with the effectiveness that the sun provides).

If at all, I would rather combine solar thermal, which unlike solar power is not only dependent on solar energy but also works with ambient heat from the air, for example (of course not as efficiently as the sun provides).

However, solar thermal can only produce hot water. What use is it to you if you can generate hot water from ambient heat (I doubt that really often brings significant yields, especially in winter!?) for relatively high investment costs but, for example, in summer, you only produce hot water instead of using the generated electricity to power the stove, washing machine, and so on?

The sun unfortunately shines when you need little or no heating water.

Besides, you need a large storage tank for solar thermal, which also needs to be heated when there is no sun, again using electricity...

Hello,

we have installed an air-to-water heat pump (hot water including ventilation) and an air heat pump (for underfloor heating). In addition, a 6kWp photovoltaic system (each 50% on the SOUTH and west side).

House size 171m2 with 2 full floors each. Including the compensation from the utility company (13.4ct/kWp), we came to heating and hot water costs of 15-20€/month in the first year of operation (2-person household).

However, this lower value is only achievable through intelligent control. There are many things to consider that a layperson would not think of, and heating engineers and electricians also find it quite difficult because the trades are not deeply interconnected.

If you want further information, just write me directly via PN.

Regards

Amin

We, living in a cold region and a 4-person household, have heating and hot water costs of €50 per month with a brine heat pump and controlled residential ventilation.
That means absolute numbers are meaningless since the properties and conditions are unknown/not comparable.

@ Jeanette: My opinion, especially for you who live in the warmest part of Germany: an air-to-water heat pump is sufficient – possibly also controlled residential ventilation for comfort reasons,
because proper ventilation is not always possible with modern houses and working residents.

Solar: the additional investment will never pay off. In winter, there is low yield anyway, and you also need a buffer storage, which significantly reduces the efficiency of the air-to-water heat pump. And in summer: 1-2 kWh per day for hot water – no solar system is needed for that.

Photovoltaics: realistically calculated barely profitable anymore, especially if financed externally. Solar installers and new photovoltaic owners often paint the picture a bit too rosy.
Good idea with a storage. But: the batteries are still very expensive and durability is not optimal. Economically calculated certainly not profitable.

The cheapest and most efficient option for you is an air-to-water heat pump – nothing else. My opinion based on the information given here.

@ Elektro1: An air heating system and additionally an air-to-water heat pump? Two heat generators?
In which climate zone is your house located, how insulated? What is your actual heat demand and consumption?