ᐅ Gas with solar thermal? Or heat pump with photovoltaic? Advice needed
Created on: 5 Feb 2020 08:57
M
Micha8589
Good morning to the forum,
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
K
knalltüte29 Apr 2020 17:02There is a specialized forum (Photovoltaics ... Forum ... de) where this topic is frequently discussed, often including the purpose of photovoltaics plus battery storage.
If I may summarize what seems to be the consensus there from my understanding:
If you install photovoltaics, then cover the entire roof and do so without a battery storage system (especially since battery storage combined with a heat pump and underfloor heating makes little sense, as the heat pump and underfloor heating themselves serve as storage for the photovoltaics – this mainly applies economically!)
Nevertheless, there are exceptions where a battery storage system can be considered "useful":
• Ecology – debatable (but I believe in it)
• Self-sufficiency – clearly
• With subsidies – economically better than without subsidies (obviously), especially long term (>20 years, if the battery lasts longer than 10–15 years (which nobody knows for sure yet))
P.S. We will likely fully equip our roof – about 23–25 kWp plus 10–15 kWh battery storage, ground-source heat pump, underfloor heating (also for cooling), controlled ventilation system. In our case: four small heat generators, KfW40+ standard = subsidies for almost everything …
If I may summarize what seems to be the consensus there from my understanding:
If you install photovoltaics, then cover the entire roof and do so without a battery storage system (especially since battery storage combined with a heat pump and underfloor heating makes little sense, as the heat pump and underfloor heating themselves serve as storage for the photovoltaics – this mainly applies economically!)
Nevertheless, there are exceptions where a battery storage system can be considered "useful":
• Ecology – debatable (but I believe in it)
• Self-sufficiency – clearly
• With subsidies – economically better than without subsidies (obviously), especially long term (>20 years, if the battery lasts longer than 10–15 years (which nobody knows for sure yet))
P.S. We will likely fully equip our roof – about 23–25 kWp plus 10–15 kWh battery storage, ground-source heat pump, underfloor heating (also for cooling), controlled ventilation system. In our case: four small heat generators, KfW40+ standard = subsidies for almost everything …
P
pagoni202013 Jun 2020 13:20@Mycraft
We are building a new single-family home and are considering the various options for heating and air conditioning. Unfortunately, there is no natural gas connection on our street, so some houses have installed propane tanks either above ground or buried underground. Generally, I like innovation, but in this case, I feel that heat pumps are too much in focus, and the efficiency of modern condensing boilers tends to be overlooked. Also, we prefer a simple and convenient heating solution.
We will have very large glass surfaces and might install solar control glass on the south side, plus external blinds (e.g. venetian blinds or louvered shutters).
Nevertheless, I am having the necessary pipe connections and outlets prepared so that an air conditioning system or an air-to-water heat pump can be installed later without much effort.
Therefore, my question is whether you would take the same position regarding liquid gas? Our lot is very large, so a propane tank (underground) is not a problem. Or does this only apply to a “normal” natural gas connection?
What should I keep in mind during the shell construction so that an air conditioner or air-to-air heat pump can be easily integrated later if needed?
Is it mandatory to install solar panels on the roof for gas heating in a new build?
We are building a new single-family home and are considering the various options for heating and air conditioning. Unfortunately, there is no natural gas connection on our street, so some houses have installed propane tanks either above ground or buried underground. Generally, I like innovation, but in this case, I feel that heat pumps are too much in focus, and the efficiency of modern condensing boilers tends to be overlooked. Also, we prefer a simple and convenient heating solution.
We will have very large glass surfaces and might install solar control glass on the south side, plus external blinds (e.g. venetian blinds or louvered shutters).
Nevertheless, I am having the necessary pipe connections and outlets prepared so that an air conditioning system or an air-to-water heat pump can be installed later without much effort.
Therefore, my question is whether you would take the same position regarding liquid gas? Our lot is very large, so a propane tank (underground) is not a problem. Or does this only apply to a “normal” natural gas connection?
What should I keep in mind during the shell construction so that an air conditioner or air-to-air heat pump can be easily integrated later if needed?
Is it mandatory to install solar panels on the roof for gas heating in a new build?
Condensing boiler technology is now well-developed and as efficient as it can be. It is also reliable enough that you could practically hit the boiler with a hammer and it would still keep running.
However...
You need to consider all costs, and if a gas connection is not possible, the balance tends to shift in favor of a heat pump.
You really have to calculate everything carefully here. A liquefied gas tank and gas deliveries are additional costs on top of that. It might be cheaper to install a heat pump with a horizontal trench collector instead.
Regarding heat pumps for cooling: you need to plan the system carefully to decide which technology you want or need.
The quickest and simplest option is an air-source heat pump. You only have to prepare the refrigerant lines, 5x1.5mm² (5x14 AWG) cables from outside to inside, and ensure condensate drainage at the locations where the indoor units will be installed.
However...
You need to consider all costs, and if a gas connection is not possible, the balance tends to shift in favor of a heat pump.
You really have to calculate everything carefully here. A liquefied gas tank and gas deliveries are additional costs on top of that. It might be cheaper to install a heat pump with a horizontal trench collector instead.
Regarding heat pumps for cooling: you need to plan the system carefully to decide which technology you want or need.
The quickest and simplest option is an air-source heat pump. You only have to prepare the refrigerant lines, 5x1.5mm² (5x14 AWG) cables from outside to inside, and ensure condensate drainage at the locations where the indoor units will be installed.
Follow up:
Dear all, also, or even primarily, thanks to the suggestions in this forum, I have now decided against an air-to-water heat pump and instead chosen a condensing gas boiler combined with solar thermal for domestic hot water heating.
Greetings to everyone who supported me in making this decision!
Dear all, also, or even primarily, thanks to the suggestions in this forum, I have now decided against an air-to-water heat pump and instead chosen a condensing gas boiler combined with solar thermal for domestic hot water heating.
Greetings to everyone who supported me in making this decision!
I
Iotafreak3 Nov 2020 12:18Mycraft schrieb:
Condensing technology is now well-developed and as efficient as it can get. It is also reliable enough that you could practically hit the boiler with a hammer and it would keep running.
But...
Of course, you have to consider all the costs, and if a gas connection is not possible, the balance tends to shift in favor of a heat pump.
You really have to calculate everything down to the last penny here. A liquefied gas tank and gas deliveries are all additional costs. It might be more cost-effective to install a heat pump with a horizontal ground loop collector instead.
Regarding heat pumps for cooling, you need to think about which technology you want or need.
The quickest and easiest option is an air source heat pump; in that case, you only need to prepare the refrigerant lines, 5x1.5 cables from outside to inside, and make sure condensate drainage is provided at the points where the indoor units will be installed. Hello,
We are still at the very beginning and just gathering ideas...
Is the gas condensing boiler with solar thermal only used for hot water or also for underfloor heating?
Do I then need two storage tanks?
What is typical... I have also read that it is only used for hot water, like for showers, etc...
Thanks for the answer
N
nordanney3 Nov 2020 12:38Iotafreak schrieb:
What is common.. I also read that it is only used for hot water, like for showers, etc... That is common and highlights the illogical situation where you have an abundance of hot water in the summer but rather little in the winter.
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