ᐅ Pellet-Solar Combination – Issues During Summer?

If you are going for photovoltaics, then install as much as possible. If you choose solar thermal, then 4-5m² (43-54 sq ft) is recommended, and if your gut feeling is undecided, just go with both. You can occasionally see this on new roofs, although it is still rather uncommon.

You can use the excess electricity generated in summer to power an air conditioning system.

XxTankerxX schrieb:

How much does a small heat pump usually cost?

It should be around 2,000 euros (plus or minus, depending on installation). This applies whether it’s Buderus, Wolf, or Vaillant.

XxTankerxX schrieb:

What do you think about this?

The man is thinking ahead. Once the hot water tank is heated through by the pellet system, the maintenance energy or reheating needed for summer consumption is manageable. Of course, an electric heating element isn’t as efficient as a heat pump, and @nordanney is absolutely right about that. However, using the heating element with surplus energy from the solar panels does have its appeal. With a feed-in tariff significantly below 8ct per kWh, which you can expect, and electricity purchase prices three to four times higher, this will have a neutral to positive effect on costs. Additionally, it feels good to use your own climate-friendly electricity.
Many of us still receive a feed-in tariff at a level that makes every square meter of photovoltaic roof space a no-brainer. That is gradually changing. Economically, optimizing self-consumption is becoming more important, as selling excess electricity back to the grid is less and less profitable.

Solar thermal has now been on the roof for 13 years (old house), still watertight, no pressure losses or need to refill glycol. Unfortunately, the roof is too small and too old for worthwhile photovoltaics, and in at most 15 years "a digger will be going through the house anyway" 😎. The new house, however, has plenty of photovoltaics installed.

But 15 kW is quite something—how large is the property, or is there a pool to be heated as well? 😉

As previous posters have already mentioned: just fill the roof with photovoltaics and optimize self-consumption (but not necessarily “force” it with a battery). There have never really been “limits,” only minor hurdles. So if 30 kWp can fit on the roof: go for it!

A heat pump likely provides a baseline electricity consumption, just like freezers and other continuous consumers. But heat pump plus pellets? High-temperature and low-temperature systems are not an ideal combination. The production costs of self-generated photovoltaic electricity currently tend to be above feed-in tariff rates if you only consider the depreciation/feed-in tariff period of 25 years. But the nice thing is that the system doesn’t just disappear after 25 years—instead, it is expected to still retain over 90% efficiency (starting at 100%).

hampshire schrieb:

The guy thinks ahead. Once the hot water tank is fully heated by the pellet system, the maintenance energy or reheating for summer consumption is manageable. Of course, an electric heating element does not have the same efficiency as a heat pump, and @nordanney is absolutely right about that. However, using the heating element with surplus energy from the solar panels is quite appealing. With a feed-in tariff well below 8 cents per kWh, which you can expect, and a purchase price three to four times higher, this will have a cost-neutral to positive effect. Besides, it feels good to use your own climate-friendly electricity.
Many of us still receive a feed-in tariff that makes every square meter of photovoltaic roof area a "no-brainer." That is slowly changing. Economically, maximizing self-consumption is gaining ground, as feeding electricity back to the grid is becoming less worthwhile.

Thank you very much for your detailed explanation.
The heating or building services technician told me that there are now smart controls available that use surplus energy for the heating element, also known as the instantaneous water heater, while the rest is fully used for the house—after one or two nights, I actually find the concept not so bad anymore. This way, I could probably size the buffer tank much smaller than with solar thermal systems. That could also offer hygienic advantages in the long run (regarding legionella, etc.).

For this reason, I no longer fully agree with the motto "as much photovoltaics as possible," especially since, as you said, the feed-in tariff is currently so low. I wonder if it might be more economical to size everything (panel area, inverter, etc.) to cover self-consumption (plus a small buffer for future needs). Am I wrong to think this?

What is this actually about? Renovation, refurbishment, or new construction?

In the case of new construction, I find it hard to fully understand the focus on the pellet heating system.