ᐅ Heat Pump with Photovoltaic System vs. Gas Heating and Solar Thermal Energy
Created on: 7 Jun 2016 21:53
I
inconel
Hello everyone,
for my house construction, which will start next year, I would like to gather information about the heating system, specifically regarding the two options:
+ Gas condensing boiler, supported by approximately 12m² (130 sq ft) of solar thermal panels and a wood stove
+ Groundwater heat pump powered by a photovoltaic system
About the property:
+ Planned is a 10x11m (33x36 ft) house with two full floors, a basement, a hip roof with about 35m² (375 sq ft) of south-facing roof area, and approximately 200m² (2,150 sq ft) of living space.
+ Exterior walls made of 36.5cm (14 inches) perlite-filled bricks “Poroton T7”
+ Location: Bavaria, with an average annual solar radiation of about 1000 kWh/m²
Option 1: Gas condensing boiler
Advantages:
- Proven, durable gas condensing technology (efficient)
- Fast response time of the gas heating system, requires no long preheating
- From around April to October, the thermal energy from the solar panels is sufficient (no gas needed); in winter, supported by the wood stove for both hot water and heating
Disadvantages:
- Solar panels need to be cooled relatively early in summer, meaning little hot water is required but excess heat must be dissipated from the panels → increased electricity and water costs without added benefit
- Large domestic hot water storage tank needed to utilize countercyclical heating periods
Option 2: Photovoltaics with heat pump
Advantages:
- Autonomous heat and electricity production
- “Green energy”
- Additional support for other continuous electricity consumers (refrigerator, freezer, washing machine, dryer)
- Relatively low effort to install suction and discharge wells, as groundwater is already available at about 2.5m (8 ft) depth
Disadvantages:
- High investment costs for both photovoltaic system and heat pump (long payback period)
- Limited sunshine during months with high energy demand
- Complex and expensive, but still necessary, storage solutions for photovoltaic electricity
I hope you can understand my concerns and ideas, and I would really appreciate your feedback. How do you see the situation? What do you think is truly practical?
Thank you very much
Best regards
for my house construction, which will start next year, I would like to gather information about the heating system, specifically regarding the two options:
+ Gas condensing boiler, supported by approximately 12m² (130 sq ft) of solar thermal panels and a wood stove
+ Groundwater heat pump powered by a photovoltaic system
About the property:
+ Planned is a 10x11m (33x36 ft) house with two full floors, a basement, a hip roof with about 35m² (375 sq ft) of south-facing roof area, and approximately 200m² (2,150 sq ft) of living space.
+ Exterior walls made of 36.5cm (14 inches) perlite-filled bricks “Poroton T7”
+ Location: Bavaria, with an average annual solar radiation of about 1000 kWh/m²
Option 1: Gas condensing boiler
Advantages:
- Proven, durable gas condensing technology (efficient)
- Fast response time of the gas heating system, requires no long preheating
- From around April to October, the thermal energy from the solar panels is sufficient (no gas needed); in winter, supported by the wood stove for both hot water and heating
Disadvantages:
- Solar panels need to be cooled relatively early in summer, meaning little hot water is required but excess heat must be dissipated from the panels → increased electricity and water costs without added benefit
- Large domestic hot water storage tank needed to utilize countercyclical heating periods
Option 2: Photovoltaics with heat pump
Advantages:
- Autonomous heat and electricity production
- “Green energy”
- Additional support for other continuous electricity consumers (refrigerator, freezer, washing machine, dryer)
- Relatively low effort to install suction and discharge wells, as groundwater is already available at about 2.5m (8 ft) depth
Disadvantages:
- High investment costs for both photovoltaic system and heat pump (long payback period)
- Limited sunshine during months with high energy demand
- Complex and expensive, but still necessary, storage solutions for photovoltaic electricity
I hope you can understand my concerns and ideas, and I would really appreciate your feedback. How do you see the situation? What do you think is truly practical?
Thank you very much
Best regards
To the original poster: Yesterday, I worked out a calculation for myself, which really helped me finally make a clear decision on this somewhat unclear topic.
According to my calculation, based on my heating load, my gas consumption costs would be around €565. A heat pump would be somewhere in the middle at about €760, assuming a seasonal performance factor (SPF) of 3. However, what’s missing with gas are the annual maintenance costs for the chimney sweep and the service contract. I estimated €200 here: about €50 for the chimney sweep and €150 for the service contract. That makes gas heating look less attractive. We would save about €2700 in initial costs overall, but then also have a gas line installed in the house. With a seasonal performance factor of 3.5, the calculation favors the heat pump much more clearly.
Our advantage is that we’re building with a fireplace, which we can use to heat in winter if needed. But only because we enjoy watching the fire, not because we have to.
It also became clear that geothermal drilling won’t pay off for us. The cost is about €8000, minus a €4500 government subsidy (BAFA), resulting in €3500 net. If I assume a seasonal performance factor of 4.5 or 5 for this system, I’d save just under €200 per year. So, €3500/€200 = 17.5 years until payback. Who knows if the pump will last that long, or if the geothermal borehole will provide energy for that time. By then, new generations of heat pumps will be available, so I’ll probably just replace my old air-to-water heat pump with a new one.
For me, it’s clear: considering the 2050 climate goals and the cost advantage compared to geothermal, the air-to-water heat pump is the best alternative. Yes, it initially costs about €2700 more than gas, but then I don’t have to worry soon about fossil fuel taxes or pressure for renovations. Increasing electricity prices due to the Renewable Energy Act surcharge can be partly offset later with photovoltaic panels.
Geothermal only comes into consideration if I find a more affordable drilling company; otherwise, the decision stays with the air-to-water heat pump.
According to my calculation, based on my heating load, my gas consumption costs would be around €565. A heat pump would be somewhere in the middle at about €760, assuming a seasonal performance factor (SPF) of 3. However, what’s missing with gas are the annual maintenance costs for the chimney sweep and the service contract. I estimated €200 here: about €50 for the chimney sweep and €150 for the service contract. That makes gas heating look less attractive. We would save about €2700 in initial costs overall, but then also have a gas line installed in the house. With a seasonal performance factor of 3.5, the calculation favors the heat pump much more clearly.
Our advantage is that we’re building with a fireplace, which we can use to heat in winter if needed. But only because we enjoy watching the fire, not because we have to.
It also became clear that geothermal drilling won’t pay off for us. The cost is about €8000, minus a €4500 government subsidy (BAFA), resulting in €3500 net. If I assume a seasonal performance factor of 4.5 or 5 for this system, I’d save just under €200 per year. So, €3500/€200 = 17.5 years until payback. Who knows if the pump will last that long, or if the geothermal borehole will provide energy for that time. By then, new generations of heat pumps will be available, so I’ll probably just replace my old air-to-water heat pump with a new one.
For me, it’s clear: considering the 2050 climate goals and the cost advantage compared to geothermal, the air-to-water heat pump is the best alternative. Yes, it initially costs about €2700 more than gas, but then I don’t have to worry soon about fossil fuel taxes or pressure for renovations. Increasing electricity prices due to the Renewable Energy Act surcharge can be partly offset later with photovoltaic panels.
Geothermal only comes into consideration if I find a more affordable drilling company; otherwise, the decision stays with the air-to-water heat pump.
I don’t understand the problem you have with heat pumps.I don’t have a problem with heat pumps; otherwise, I wouldn’t be considering them. For me personally, though, I just don’t see a solution. I have already emphasized that everyone should form their own opinion based on different installations and their respective reasons.
It might not be worth it in your situation, but in other cases, heat pumps are definitely a good and cost-effective alternative. You just don’t want to admit that.I rather get the impression that you don’t want to acknowledge that there are also reasons against a heat pump. And a heat pump is not cheap. It may pay off over the years, but the initial investment is high, and that’s exactly why we are discussing this here…
Also: the higher the demand, the more important the operating costs are. That’s why all heating technologies have their justification.I agree with you 100%.
Additionally, I would have had to buy a gas/oil tank, which adds significant cost, ongoing expenses, and requires space. For me, a slightly higher investment means lower operating costs. What would the solution with a gas boiler + underground tank and fireplace have cost you?Which chimney sweep would approve that gas boiler setup of yours and allow you to operate it? Anyone — this is not a makeshift solution; it is built like this, especially if you don’t have space in the basement. Just Google heating in the attic.But in that price range, you don’t get a boiler with 95% efficiency at 25 kW output, do you? Yes, it is a Vaillant unit with a seasonal efficiency of 109%.I also already wrote that my COMPLETE heating system cost 12k (gas boiler Vaillant 226/4 23 kW, 2000 l (530 gallons) buffer tank, Vaillant solar station, chimney for the gas condensing boiler is a 50 mm (2 inch) plastic pipe, 7 m² (75 sq ft) solar panels from Wagner).
The additional cost for the water jacket was €1,500. The masonry heater (including chimney, water jacket, etc.) cost 13k. However, I would have installed the masonry heater anyway—not for heating, but for the ambiance and because I enjoy sitting by a warm stove and watching the fire. The idea behind the water jacket was simply that you can stoke the stove even when you don’t actually need ‘heat.’ That way, I can enjoy the fire even when it’s 20°C (68°F) outside and store the heat in the buffer.
And the fact that I’m not completely off track with heat pumps is shown by tabtab’s post.
The post by tabtab also demonstrates that heat pumps can be worthwhile, especially when you have a high demand. The lower the basic heating costs, the less you can save. Given your large demand, the operating costs clearly favor a heat pump. With an affordable electricity tariff (for example, enabled by solar power), an air-source heat pump could already work well for saving energy.
Regarding tank costs and space, I can only comment once I’m at home. However, just the space needed for a tank is worth several thousand euros, and gas from a tank is even more expensive than from a pipeline (which further increases the operating cost advantage of the heat pump).
Regarding tank costs and space, I can only comment once I’m at home. However, just the space needed for a tank is worth several thousand euros, and gas from a tank is even more expensive than from a pipeline (which further increases the operating cost advantage of the heat pump).
If you want, we can continue this in a private message, but I don’t think it makes much sense to keep discussing it here.
Your position is clear, and so is mine. In the coming years, neither of us will need to take action. However, for those who are building new and have to make a decision, I believe this discussion has been worthwhile.
Therefore, anyone installing a heating system and deciding on the energy source must first consider their OWN circumstances and then calculate what makes the most sense.
Personal preferences also need to be taken into account.
Personally, I love my tiled stove, and I could watch the fire for hours. I can sit there with a glass of red wine and relax, which is (not only) priceless TO ME!
Your position is clear, and so is mine. In the coming years, neither of us will need to take action. However, for those who are building new and have to make a decision, I believe this discussion has been worthwhile.
Therefore, anyone installing a heating system and deciding on the energy source must first consider their OWN circumstances and then calculate what makes the most sense.
Personal preferences also need to be taken into account.
Personally, I love my tiled stove, and I could watch the fire for hours. I can sit there with a glass of red wine and relax, which is (not only) priceless TO ME!
Tom1607 schrieb:
That’s why anyone installing a heating system and deciding on the energy source first needs to consider THEIR specific circumstances and then calculate what makes sense.
!That is, at the end of the day, the summary answer! (even if it doesn’t fully align with your previous statement that you should always use district heating)That’s exactly what I already wrote, only that for me, neither red wine, nor any other alcohol, nor fire is necessary for relaxation—in fact, quite the opposite. But in other threads, the general opinion was also that fireplaces are a matter of personal taste, and only really practical for primary heating if you can get wood cheaply.
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