ᐅ Is it worthwhile to use a cloud-based solution alongside an energy storage system?

We are planning to build a new house. Approximately 120 sqm (1,292 sq ft) of living space on the ground floor for two people (retirees), and a single one-bedroom apartment upstairs for a working individual.

A gable roof oriented east-west is planned. We intend to install a photovoltaic system and a heat pump with underfloor heating. According to our information, a ground-source heat pump is more efficient than an air-source heat pump, although the former has higher upfront costs. However, this is offset by higher subsidies for the ground-source heat pump.

A tradesperson also recommends adding a storage system for peak production times. This would result in an annual self-sufficiency rate of about 50%. Others suggest using a “cloud” storage option (instead of feeding excess energy into the grid with currently low feed-in tariffs), where energy that does not fit into the storage can be saved and then retrieved in winter. However, I wonder how this works, as everyone requires more energy in winter than they produce themselves. According to the vendor of this product, the “cloud” solution would enable autonomy of 70 to 80%.

Who can calculate which is the most practical solution?

Storage is not worth it; you can only do it out of interest or as a hobby. Cloud services are even less worthwhile—no one is giving anything away for free. You will end up being taken advantage of by the "seller."

I don’t fully understand the second part. If something is more efficient, it is usually more expensive, but as you write, there are subsidies that don’t really make up for the difference, unless you provide your own labor.

Heidi1965 schrieb:

A craftsman also recommends a storage system to handle production peaks. That way, you could achieve a self-sufficiency rate of about 50% over the year.

That’s not untrue, but autarky is a figure that benefits neither the environment nor your budget. Without storage, you might reach around 30%, depending on your usage profile. So who exactly benefits from that extra 20%, and how?

With storage, you pay for it or make less profit from photovoltaics, because the storage system itself doesn’t pay off economically. Photovoltaics, on the other hand, do pay off, so it makes sense to maximize the available surface area. More photovoltaics also mean a bit higher self-sufficiency during transitional seasons, if that’s a goal for you.

Exception: with standards like KfW 40+, storage systems are subsidized and can be economically viable.

If storage systems become cheaper, then it’s worth reconsidering.

Heidi1965 schrieb:

Others recommend using the “cloud” (instead of feeding excess electricity into the grid at currently low feed-in tariffs), where surplus energy that doesn’t fit into the battery can be stored and then retrieved in winter.

Just don’t.

I haven’t examined cloud solutions in detail. What I’ve understood is that sellers and providers benefit more than you do. These products are opaque for good reason. For example, you bear the risk for the storage technology, while receiving some kind of non-guaranteed flat-rate electricity with minimum take-or-pay agreements.

Cloud solutions are also complicated when it comes to taxes, which may generate further advisory costs.

Heidi1965 schrieb:

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

That’s generally correct, and here someone clearly had more expertise than many others.

Whether this applies in your specific case must be calculated individually. In particular, the purchase prices for the equipment matter. If you calculate this yourself, keep in mind that the heat pump will eventually have to be replaced, and you should factor that in. The savings from the higher efficiency are not huge in new builds. Ground-source heat pumps can be somewhat more complex if problems occur. The downside of air-to-water heat pumps is the outdoor unit. If you live in a very cold location or have issues with the outdoor unit, I would recommend ground-source.

For a heat pump, good planning is crucial for efficiency. This is not automatic, and you shouldn’t trust installers without control: have underfloor heating planned based on room-by-room heat load calculations for low flow temperatures (around 30°C (86°F) or less), avoid buffer tanks, and don’t oversize the heat pump.

None of the things you listed make financial sense. If you want to do them anyway because you have enough money, then go ahead. They are nice "extras."

Which heating system do you recommend?

It depends on personal needs, as there is no longer a right or wrong choice nowadays.

Overall, gas is still the most cost-effective option and a very reliable technology.

For those who do not like gas and find the idea of burning fossil fuels outdated, switching to an electric alternative is necessary.

Air source heat pumps are a good option. However, noise and the outdoor unit’s appearance in the garden should be considered. Combined with photovoltaics, this is a very good solution.

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