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
For me, the big question is always that when I need heat (winter), the sun shines too little (electricity drawn from the grid). But in summer, the sun is intense, and I don’t need heating.
My solution is a gas condensing boiler + solar thermal system + masonry stove with water jacket + photovoltaic system (30kW). In summer, the hot water is heated by solar thermal. During transitional seasons and winter, stove + gas are used. Photovoltaics cover self-consumption and feed-in.
A concrete example of the photovoltaic system’s output in 2015: January, February, October, November, December → 4,400 kWh. In April alone, the system produced 4,600 kWh! Over the entire winter (5 months), the total electricity generated is about the same as in April... And with that, you want to heat the house...
This shows how twisted this whole situation is. Storing the excess energy from summer is not practical. That’s why I would ALWAYS use solar thermal, whether with gas or heat pump. Controlled mechanical ventilation is essential for me anyway (with today’s well-sealed houses).
My solution is a gas condensing boiler + solar thermal system + masonry stove with water jacket + photovoltaic system (30kW). In summer, the hot water is heated by solar thermal. During transitional seasons and winter, stove + gas are used. Photovoltaics cover self-consumption and feed-in.
A concrete example of the photovoltaic system’s output in 2015: January, February, October, November, December → 4,400 kWh. In April alone, the system produced 4,600 kWh! Over the entire winter (5 months), the total electricity generated is about the same as in April... And with that, you want to heat the house...
This shows how twisted this whole situation is. Storing the excess energy from summer is not practical. That’s why I would ALWAYS use solar thermal, whether with gas or heat pump. Controlled mechanical ventilation is essential for me anyway (with today’s well-sealed houses).
G
Goldi0911119 Jun 2016 10:28Sorry, but in my opinion, a gas condensing boiler and photovoltaic system are not practical together, and the additional costs for a stove with a water jacket never pay off unless you get the wood for free.
If photovoltaic, then only in combination with a heat pump or a very high self-consumption due to large electricity consumers in the home, right?
If photovoltaic, then only in combination with a heat pump or a very high self-consumption due to large electricity consumers in the home, right?
Tom1607 schrieb:
That’s why I would ALWAYS use solar thermal, whether you have gas or a heat pump. Controlled mechanical ventilation is a must for me anyway (especially with nowadays airtight houses).However, it only benefits you during good winter days, and in summer, unlike photovoltaic systems, it practically provides almost no advantage. With photovoltaic systems, you can at least sell the electricity or power devices other than the heat pump. In my opinion, solar thermal is "useless" on the roof for about three quarters of the year.
T
toxicmolotof19 Jun 2016 11:19Photovoltaics and air conditioning are excellent, photovoltaics and pool heating are excellent, photovoltaics and electrical appliances are excellent.
Solar thermal is only really useful for domestic hot water. It is not practical for anything else.
You will always have the winter problem, whether it is photovoltaics or solar thermal. The only solutions are fossil fuels or the utility provider.
Solar thermal is only really useful for domestic hot water. It is not practical for anything else.
You will always have the winter problem, whether it is photovoltaics or solar thermal. The only solutions are fossil fuels or the utility provider.
My photovoltaic system generates a return of about 9%, which I think is definitely worthwhile. At least it's better than the 0.5% from the bank.
I have the stove for the ambiance. You can't justify it economically. The additional cost for the water jacket was €1,500 (about $1,600), so why wouldn’t I combine it? Especially during the transitional seasons, it’s practical because you can use it to heat the buffer tank.
The buffer tanks are there anyway because of the solar system...
A heat pump is not for me, because I won’t recover the extra investment cost in 30 years, and rising electricity prices would affect me negatively. When I need heating, the photovoltaic system produces too little, so I would have to buy electricity...
I have the stove for the ambiance. You can't justify it economically. The additional cost for the water jacket was €1,500 (about $1,600), so why wouldn’t I combine it? Especially during the transitional seasons, it’s practical because you can use it to heat the buffer tank.
The buffer tanks are there anyway because of the solar system...
A heat pump is not for me, because I won’t recover the extra investment cost in 30 years, and rising electricity prices would affect me negatively. When I need heating, the photovoltaic system produces too little, so I would have to buy electricity...
Tom1607 schrieb:
My photovoltaic system generates a return of about 9%, so I think it’s definitely worthwhile. At least better than the 0.5% from the bank.
I have the stove for the ambiance. Economically, it doesn’t make sense. The additional cost for the water jacket was €1,500 (about $1,600), so why not combine it? Especially practical during transitional seasons since it can operate the buffer tank.
The buffer tanks are there anyway because of the solar system...
A heat pump isn’t for me because I won’t recover the extra investment costs within 30 years, and rising electricity prices would affect me. When I heat, the photovoltaic system produces too little, so I have to buy electricity…Well, with the price of your water jacket alone (without anything else), my heat pump can already cover 5 years of heating and hot water production (completely!). And overall, the water jacket barely adds any value throughout the year; you’d have to use the fireplace a lot and get the wood for free (and if you have to pay for the wood, heating with a heat pump is probably cheaper—wood is getting more expensive nowadays too). If electricity prices rise, you can probably sell the generated electricity at a higher rate.
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