Is the cloud solution also sensible alongside a power storage system?

We are planning the new construction of a house. Approximately 120 sqm of living space downstairs for 2 people (retirees), upstairs a single flat for a working person.

A gable roof facing east or west is planned. There will be a photovoltaic system, a heat pump with underfloor heating. According to our information, a brine heat pump is more efficient than an air heat pump, although the former is more expensive to purchase. However, this is offset again by the higher subsidy for the brine heat pump.

A craftsman additionally recommends a storage system for production peaks. This would result in a self-sufficiency rate of about 50% over the year. Others also recommend the "Cloud" (instead of feeding into the grid at the currently low remuneration rates), where what does not fit into the storage can be stored and then retrieved again in winter. However, the question arises for me how this works because everyone needs more in winter than they produce themselves. With the "Cloud" solution, one would have autonomy of 70 to 80%; according to the seller of this product.

Who can calculate what the most sensible solution is?

Storage is not worth it, you can only do it out of interest/playfulness. Cloud is even less worthwhile, no one gives you anything... There you will be nicely ripped off by the "seller."

I don't quite understand the 2nd paragraph, if something is more efficient, it is usually also more expensive, but as you write, there are subsidies, but they do not compensate for this, except in the case of own contribution.

A craftsman additionally recommends a storage system for production peaks. This would result in a self-sufficiency rate of about 50% over the year.

That is not a lie, but autonomy is a metric that benefits neither the environment nor the wallet. Without storage, you might have about 30%, depending on the usage profile. For whom exactly do those 20% make what kind of difference now?

With storage, you pay for it or have less profit from photovoltaics because the storage system itself is not cost-effective. Photovoltaics, on the other hand, pay off, so try to use as much surface area as possible. More photovoltaics also means somewhat more autonomy during the transition period if that is a goal for you.

Exception: For Kfw 40+ the storage is subsidized and can be cost-effective.

When storage systems become cheaper, then you can consider it.

Others still recommend the "Cloud" (instead of feeding into the grid at the currently low feed-in tariffs), where what no longer fits into the storage can be stored and then retrieved again in winter.

Just leave it.

I have not dealt with cloud solutions in detail. What I have understood is that the sellers and providers of these products profit more than you do. The products are non-transparent, for good reason. You, for example, bear the risk for the storage technology, and in return get some kind of non-permanently guaranteed flat rates for electricity with minimum consumption.

Also, cloud solutions are difficult to handle from a tax perspective, which may involve additional advisory costs.

According to our information, ground-source heat pumps are more effective than air-source heat pumps, although the former is more expensive to purchase. However, this is compensated by the higher subsidies available for ground-source heat pumps.

That is generally correct, and someone had more expertise than many others.

Whether this applies in the individual case must be calculated individually. In particular, it depends on the purchase prices for the technology. If you recalculate, keep in mind that the heat pump will eventually have to be replaced, and this should be included. The savings through the higher efficiency are not huge in new buildings. Ground-source heat pumps can be somewhat more complex if problems arise. The disadvantage of air-water heat pumps is the outdoor unit. If you live in a very cold location or have issues with the outdoor unit, I would choose ground-source.

For a heat pump, it is very important for efficiency that the planning is good. This is not a given, and you should not trust craftsmen without control here: have the floor heating planned based on room-by-room heating load calculation for low supply temperature (around 30°C or less), no buffer tank, do not oversize the heat pump.

Everything you listed does not make financial sense. If you want to do it because there is enough money anyway, then go ahead. They are nice "playthings"

Which heating system do you recommend?

That depends on personal needs, nowadays there is no right or wrong anymore.

Overall, it can be said that gas is still the cheapest option and a very reliable technology.

For people who do not like gas and find the idea of burning raw materials outdated, they have to switch to an alternative with electricity.

Air heat pumps are good. The disadvantages of noise and the appearance of the outdoor unit in the garden must be considered. In combination with [Photovoltaik] a very good thing.

Pellets are an option if there is a high heating demand or no gas connection is available.