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
€60,000 for a heat pump? Then it must be covered in gold leaf, right? :x *duck*More like platinum.
Joking aside, I have a heating load of 25 kW and that capacity has to come from somewhere.
Back in 2012 when I bought the heating system, costs were in that range. I’m not sure if prices have changed much since then.
The brine-to-water heat pump itself costs around €10,000 (including accessories). The drilling is, of course, variable—and with higher heating loads, it becomes significantly more expensive. In addition, you generally cannot operate with a low supply temperature (unless the living area is around 500 m² (5,400 sq ft)). In that case, I would probably consider gas or pellets—simply more robust.
Alternatively, you could consider options to reduce the heating load.
Alternatively, you could consider options to reduce the heating load.
Tom1607 schrieb:
If you have a heating load of 8400 kWh, that corresponds to about 850 liters (225 US gallons) of heating oil (if gas is not available, then there would be liquefied gas with an underground tank). At current prices, that would be around €400 per year.
Why shouldn't there be an ROI? I would have to invest €60,000 for the heat pump solution versus €12,500 for the gas condensing boiler solution??? That would be €47,500 EXTRA COST – when would I get that back => ROI??
If I can get the heat pump solution for €30,000 in 10 years, then I would have the gas condensing boiler installed...
Where is my reasoning error here???
I don’t pay 20 cents as you do, but only 1.5 cents. Okay, I have to store the wood and start the stove, but I would do that anyway because I like this kind of warmth.
I don’t have a fireplace stove that 'glows'; my stove is 2.5 meters long (8 feet) and acts as a room divider between the living area and the kitchen/dining area. It slowly releases the stored heat into the room. If I add wood for the last time at 6 p.m., the next morning the surface temperature is around 30°C (86°F). When I sit on the stove bench with my coffee in the morning, I have a nicely warm back...
My energy supplier is the grid operator (Bayernwerk AG, formerly E.ON). I need to check if it is actually possible to change the supplier. However, I don’t know what would happen to the 10% of unreimbursable feed-in electricity. So far, it has been offset against my consumption... We are talking about around 3000 kWhI don’t have time right now, but your numbers don’t add up at all. Your stated 10 kg of wood costs €1.45 according to your own figures (that would make 100 kg cost €14.50 and 550 kg your stated price), and it produces significantly less heat than the heat pump for €1. You want to compare and talk numbers, but they are all wrong (including the heating oil figure). Calculate carefully!
ROI refers to a return as a ratio of profit to capital, but a heating system does not generate profit; it only costs money. This term at best applies to your solar system.
Also, you haven’t said anything about solar thermal yet.
And the reasoning error lies in the higher consumption of the gas boiler.
By the way, there are also heat pumps available for 50 kW load and higher without any problems.
your numbers don’t add up at all.That's correct.
1 cubic meter of wood costs €80 and weighs 550kg. With an efficiency of 80%, that equals 440kg usable fuel. At €1.81 per 10kg, 10kg of wood provides a heating energy of 10 * 4 = 40 kWh. Dividing €1.81 by 40 kWh gives a cost per kWh at 80% efficiency of €0.045 (I’m not sure where I made the calculation error before).
If I now consider your electricity price of 20 cents (I currently pay €0.31 gross) and a performance factor (COP) of 6, I don’t see any significant savings that would justify the higher investment in a heat pump system.
The heat pump was originally offered to me at a price far beyond what I was willing to invest. Besides, if I look at the investment from Sarrus for an 8 kW heating demand, it was €20,000; just the difference compared to my current heating system is already €7,500 extra cost.
For me, the ROI consideration is not just the heating system itself, but the ADDITIONAL COSTS that the heat pump solution would have caused me.
People say how great the heat pump is and how efficient and economical it is...
ONLY I DON’T SEE IT.
Maybe someone can explain where I’m wrong in thinking that I would be better off financially with a heat pump... Please help me see through my blind spot, because based on the numbers discussed so far, I don’t see any significant savings that would justify the additional costs.
Furthermore, you certainly can’t work with low flow temperatures (unless it’s a 500 sqm living area) – in that case I’d also consider gas or pellets – simply more robust. Areas:
Underfloor heating area: 240 sqm (square meters) (2583 sq ft) apartment on the ground floor, and 340 sqm (3659 sq ft) office on the upper floor,
without underfloor heating in the ground floor heating/technical room and garage of 100 sqm (1076 sq ft).
The brine-to-water heat pump itself costs around €10,000 (including accessories). The borehole, of course, is variable – and with higher heating loads that becomes significantly more expensive. A wall-mounted gas condensing boiler costs around €2,000. Installed in the attic with a 50mm (2 inch) plastic pipe through the roof for exhaust gases, and that’s it... No need to build a chimney or boiler room.
oleda222 schrieb:
You make completely unsupported claims and expect me to research them for you?
How about you put in the effort to provide evidence for your wild assertions?Why unsupported? Just because you lack the knowledge, or what? If you know better, why don’t you argue against it? Or instead, take the time to fill your knowledge gaps. Since when is that someone else’s job? Do you act like that at your job too?
In this price range, you won’t find a gas boiler with a 95% efficiency at 25 kW output. Which chimney inspector would approve this gas boiler installation in your setup, allowing me to operate it? It doesn’t get more obvious than that.
With your previous example using wood (with the buffer tank temperature), you didn’t achieve 40 kWh but 23 kWh with 10 kg. With my electricity price, the savings seem small (1 cent less), but percentage-wise that’s 25%. Besides, you haven’t mentioned the costs of the fireplace, water jacket, and large buffer tank yet. I only have the heat pump with an integrated storage unit to compare. So don’t just compare the costs of the boiler.
Additionally, I would have had to buy a gas/oil tank, which adds significant upfront costs, ongoing expenses, and requires space. For me, that means slightly higher investment but lower operating costs.
I don’t understand your issue with the heat pump. It may not be worth it for your specific situation, but for others, heat pumps are definitely a good and cost-effective alternative. You just don’t want to accept that.
Also, the higher the demand, the more important operating costs become. That’s why every heating technology absolutely has its legitimate purpose.
With your previous example using wood (with the buffer tank temperature), you didn’t achieve 40 kWh but 23 kWh with 10 kg. With my electricity price, the savings seem small (1 cent less), but percentage-wise that’s 25%. Besides, you haven’t mentioned the costs of the fireplace, water jacket, and large buffer tank yet. I only have the heat pump with an integrated storage unit to compare. So don’t just compare the costs of the boiler.
Additionally, I would have had to buy a gas/oil tank, which adds significant upfront costs, ongoing expenses, and requires space. For me, that means slightly higher investment but lower operating costs.
I don’t understand your issue with the heat pump. It may not be worth it for your specific situation, but for others, heat pumps are definitely a good and cost-effective alternative. You just don’t want to accept that.
Also, the higher the demand, the more important operating costs become. That’s why every heating technology absolutely has its legitimate purpose.
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