ᐅ Heat Pump with Photovoltaic System vs. Gas Heating and Solar Thermal Energy

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

If I were to start building in 2016, I would try to include gas, controlled ventilation, and good insulation. If that doesn’t work out, I would consider solar thermal panels on the roof. A heat pump would be too complicated for me and less reliable in terms of performance (cold winters → heat pump performs poorly; uncertain electricity prices, and so on).

merlin83 schrieb:
If I were to start building in 2016, I would try gas, mechanical ventilation with heat recovery, and good insulation. If that didn’t work out, I would install solar thermal on the roof. Heat pumps seem too complicated and unreliable in terms of performance (cold winters → heat pump performs poorly; uncertain electricity prices, and so on).

That’s not entirely correct about heat pumps, since it’s not an air-source heat pump. Heat pumps are absolutely easy to operate and require little maintenance (I suppose groundwater heat pumps need filter replacements). With my ground-source heat pump, I achieved a seasonal performance factor of over 6 (okay, mild winters). Electricity prices are just as stable or unstable as gas prices. Other users here are also doing very well with a heat pump and solar combination.

We had similar considerations and were initially against the heat pump because it costs us €2700 more upfront, even after deducting the gas connection. However, the electricity lobby is so strong that we expect significant disadvantages in a short time. You can already see this directly on the energy performance certificate. With a heat pump, you get better ratings and an energy efficiency label of A+, while gas only gets B. In the future, it will likely get even worse, as the system increasingly favors electricity. This will become a disadvantage at the latest during the next mandatory renovation or when renting or selling the property. Welcome to the world of the energy lobby...

I pay €40 per month for heating. My used car has cost me the equivalent of 100 months (!) of heating... so I would rather say it’s the harmful car lobby...

tabtab schrieb:
We had similar considerations and were against the heat pump because it initially costs us 2700€ more, excluding the gas connection. However, the electricity lobby is so strong that we fear significant disadvantages in the near future. You can already see it directly from the energy performance certificate. With a heat pump, you get better values and an energy efficiency label of A+, with gas only B. In the future, this will probably get even worse, as the balance will increasingly shift in favor of electricity. That will backfire at the latest with the next renovation obligation or when renting/selling. Welcome to lobby-driven energy policy...

Can you provide somewhat solid evidence for this, or is it just barroom talk from last weekend? The improved status of electricity from earlier this year did have quite understandable reasons.