ᐅ Gas with solar thermal or heat pump? And possibly photovoltaic panels as well?
Created on: 18 Oct 2019 14:23
H
Hausbau129
Hello everyone,
We are a family of five building a solid-constructed house in southern Germany (160 sqm (1722 sq ft) living space + basement). Now we need to decide on the heating/hot water system. Since the question mainly concerns solar/photovoltaics, I hope this is the right place to ask.
We have chosen underfloor heating with gas. To meet the energy-saving regulations, an additional renewable component is required, such as a combination with solar thermal.
After consulting with the house provider, we have three options. Since I am unsure, I would be very grateful for some feedback on our situation.
Option 1:
Gas + solar thermal
Total cost: approx. €10,000
Payback period for solar thermal: savings of about €300 heating costs per year. According to the house provider, the solar system pays off in 15-20 years.
This seemed to me like a worry-free solution that works quite reliably.
Option 2:
Gas (only for underfloor heating) + separate domestic hot water heat pump Brötje BTW 300 (to meet energy-saving regulations instead of solar thermal)
The domestic hot water heat pump is installed in the basement equipment room and is intended to warm the domestic water using the ambient air in the basement.
Total cost: approx. €6,000
I like the low total cost. It is clear that we will have a higher electricity bill due to the heat pump. I wonder if the system produces enough domestic hot water for five people, especially if several shower one after another.
Option 3:
Gas + domestic hot water heat pump (like option 2)
+ photovoltaic system to partially power the heat pump with generated electricity
Total cost: approx. €15,000
Payback period for photovoltaic system: savings/feed-in tariff about €1,000 per year. According to the house provider, it pays off in 8-10 years.
The downside is of course the higher total cost. However, if you really "earn" or save €1,000 per year, that would be acceptable for me.
Question 1: Domestic hot water heat pump Brötje BTW 300
Does anyone have experience with this heat pump or similar systems? Does it produce enough hot water for five people? Are these systems mature and reliable?
Question 2: Photovoltaic system
So far, I haven’t really dealt with this topic because I thought it no longer made sense with the low feed-in tariffs. I do not want a battery. If any, just a photovoltaic system on the roof where part of the electricity is consumed directly and the rest is fed into the grid.
Would you currently still plan to install a photovoltaic system?
Question 3: Which option would you prefer?
We would like a system that requires as little maintenance as possible, is reliable, uncomplicated, and affordable.
I am very grateful for any feedback.
Best regards
We are a family of five building a solid-constructed house in southern Germany (160 sqm (1722 sq ft) living space + basement). Now we need to decide on the heating/hot water system. Since the question mainly concerns solar/photovoltaics, I hope this is the right place to ask.
We have chosen underfloor heating with gas. To meet the energy-saving regulations, an additional renewable component is required, such as a combination with solar thermal.
After consulting with the house provider, we have three options. Since I am unsure, I would be very grateful for some feedback on our situation.
Option 1:
Gas + solar thermal
Total cost: approx. €10,000
Payback period for solar thermal: savings of about €300 heating costs per year. According to the house provider, the solar system pays off in 15-20 years.
This seemed to me like a worry-free solution that works quite reliably.
Option 2:
Gas (only for underfloor heating) + separate domestic hot water heat pump Brötje BTW 300 (to meet energy-saving regulations instead of solar thermal)
The domestic hot water heat pump is installed in the basement equipment room and is intended to warm the domestic water using the ambient air in the basement.
Total cost: approx. €6,000
I like the low total cost. It is clear that we will have a higher electricity bill due to the heat pump. I wonder if the system produces enough domestic hot water for five people, especially if several shower one after another.
Option 3:
Gas + domestic hot water heat pump (like option 2)
+ photovoltaic system to partially power the heat pump with generated electricity
Total cost: approx. €15,000
Payback period for photovoltaic system: savings/feed-in tariff about €1,000 per year. According to the house provider, it pays off in 8-10 years.
The downside is of course the higher total cost. However, if you really "earn" or save €1,000 per year, that would be acceptable for me.
Question 1: Domestic hot water heat pump Brötje BTW 300
Does anyone have experience with this heat pump or similar systems? Does it produce enough hot water for five people? Are these systems mature and reliable?
Question 2: Photovoltaic system
So far, I haven’t really dealt with this topic because I thought it no longer made sense with the low feed-in tariffs. I do not want a battery. If any, just a photovoltaic system on the roof where part of the electricity is consumed directly and the rest is fed into the grid.
Would you currently still plan to install a photovoltaic system?
Question 3: Which option would you prefer?
We would like a system that requires as little maintenance as possible, is reliable, uncomplicated, and affordable.
I am very grateful for any feedback.
Best regards
H
Hausbau12920 Oct 2019 17:57Thank you very much for all the feedback. It really helps me to think things through further. We will now need to clarify a few facts and request some quotes. Then we can look at everything in a more concrete way. Thanks again for your responses. You have helped us gain a much clearer understanding.
L
lucciano-s12 Dec 2019 16:42Hello @Hausbau129, maybe you can help me. I want to install a gas heating system combined with photovoltaic panels. Can you tell me if this is compliant with the Energy Saving Ordinance? Unfortunately, I can't find any information on this. What did you decide?
We are building monolithically with Poroton blocks without an additional composite system.
We are building monolithically with Poroton blocks without an additional composite system.
lucciano-s schrieb:
Hello @Hausbau129, maybe you can help me. I want to install a gas heating system, but combined with photovoltaics. Can you tell me if this is compliant with the Energy Saving Ordinance? Unfortunately, I can’t find any information about this. What did you decide?
We are building monolithically with Poroton blocks without an additional composite system. That won’t work. The Renewable Energy Heat Act requires a renewable energy share for hot water generation and heating. You can only achieve this with photovoltaics if you use an electric heating element to consume the generated electricity. Of course, this is not economical.
Do you have a mechanical ventilation system with heat recovery? That can also be an option.
L
lucciano-s12 Dec 2019 17:21Thank you for your feedback. Can I use the photovoltaic system for both hot water preparation and private consumption? Why is this less cost-effective than solar thermal?
A mechanical ventilation system with heat recovery is not currently planned. However, I would consider it in combination with a gas system.
A mechanical ventilation system with heat recovery is not currently planned. However, I would consider it in combination with a gas system.
Generating one kWh of electricity from photovoltaic panels costs about 4 cents. If you use it yourself, you also pay roughly 4 cents in sales tax. Additionally, you forfeit the feed-in tariff of around 10 cents per kWh.
This means that one kWh of photovoltaic electricity converted into heat by an electric heating element ultimately costs you about 18 cents.
One kWh of gas costs 5 to 6 cents, which is about one third of that.
Photovoltaic electricity—yes, definitely. But converting it into heat 1:1 is not a smart choice. It’s better to feed it into the grid because that’s where you make a profit.
This means that one kWh of photovoltaic electricity converted into heat by an electric heating element ultimately costs you about 18 cents.
One kWh of gas costs 5 to 6 cents, which is about one third of that.
Photovoltaic electricity—yes, definitely. But converting it into heat 1:1 is not a smart choice. It’s better to feed it into the grid because that’s where you make a profit.
H
Hausbau12912 Dec 2019 17:33lucciano-s schrieb:
Hello @Hausbau129, maybe you can help me. I want to install a gas heating system combined with photovoltaic panels. Can you tell me if this is compliant with the energy saving regulations? I couldn’t find any information on this. What did you decide? We are building monolithically with Poroton blocks without an additional composite system. Unfortunately, I cannot really help with specific questions about the energy saving regulations. We also relied on the advice of our heating specialist. We have now decided on a gas heating system combined with a domestic hot water heat pump. No solar panels and no photovoltaic for the time being (but the system is prepared for it). We also have a controlled mechanical ventilation system.
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