ᐅ Is it still worthwhile to install a solar thermal system when you already have an air-to-water heat pump and photovoltaic panels?
Created on: 16 Dec 2019 13:08
L
ludwig88sta
Hello everyone,
We are planning to install a photovoltaic system on the fully south-facing pitched roof of our planned house. Since we also want underfloor heating, an air-to-water heat pump is currently our preferred heating option.
I have read here in the forum that with an air-to-water heat pump, a solar thermal system— which heats water using solar energy—would be unnecessary. In other words, on sunny days, the air-to-water heat pump powered by photovoltaic electricity heats the water more efficiently and cost-effectively, right?
Is this still the current understanding as of 2019, so that with a photovoltaic system plus an air-to-water heat pump, the roof is covered only with photovoltaic panels instead of leaving space for a solar thermal system? How did you approach this?
Thanks in advance and have a great start to the week,
ludwig88sta
P.S.: Side question: if you plan a photovoltaic system on the entire south-facing roof, what type of roof tiles do you use? Naturally, as affordable as possible. What do you think about photovoltaic roof tiles (tiles with integrated photovoltaic modules)? Probably more expensive than installing regular photovoltaic panels on a tiled roof, right?
We are planning to install a photovoltaic system on the fully south-facing pitched roof of our planned house. Since we also want underfloor heating, an air-to-water heat pump is currently our preferred heating option.
I have read here in the forum that with an air-to-water heat pump, a solar thermal system— which heats water using solar energy—would be unnecessary. In other words, on sunny days, the air-to-water heat pump powered by photovoltaic electricity heats the water more efficiently and cost-effectively, right?
Is this still the current understanding as of 2019, so that with a photovoltaic system plus an air-to-water heat pump, the roof is covered only with photovoltaic panels instead of leaving space for a solar thermal system? How did you approach this?
Thanks in advance and have a great start to the week,
ludwig88sta
P.S.: Side question: if you plan a photovoltaic system on the entire south-facing roof, what type of roof tiles do you use? Naturally, as affordable as possible. What do you think about photovoltaic roof tiles (tiles with integrated photovoltaic modules)? Probably more expensive than installing regular photovoltaic panels on a tiled roof, right?
L
ludwig88sta17 Dec 2019 19:29Basically, the same air-to-water heat pump operates both systems in two separate circuits / water tanks:
1) for underfloor heating at 30°C (86°F)
2) for domestic hot water at 60°C (140°F)
Ideally, both are powered during the day by photovoltaic electricity from the roof.
1) for underfloor heating at 30°C (86°F)
2) for domestic hot water at 60°C (140°F)
Ideally, both are powered during the day by photovoltaic electricity from the roof.
B
boxandroof17 Dec 2019 19:34Exactly, it switches between the circuits using a valve.
For showering, about 40°C (104°F) is sufficient. My heat pump can reach up to 55°C (131°F), but that becomes inefficient. It is sensible to keep lower temperatures in the storage tank, up to about 50°C (122°F), and to use the water regularly: the tank should not be too large and should be sized according to individual consumption.
For showering, about 40°C (104°F) is sufficient. My heat pump can reach up to 55°C (131°F), but that becomes inefficient. It is sensible to keep lower temperatures in the storage tank, up to about 50°C (122°F), and to use the water regularly: the tank should not be too large and should be sized according to individual consumption.
L
ludwig88sta17 Dec 2019 19:35I was thinking about 60°C (140°F) because of legionella. But for showering, we don’t really need that high. 40°C (104°F) is usually enough. However, the risk in a single-family house is generally quite low, right?
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boxandroof17 Dec 2019 19:46a) low temperatures, appropriately sized hot water storage tank with regular consumption
b) high storage temperatures or regular legionella control program
c) instantaneous water heater
In a single-family home, the risk does not seem very high, but legionella bacteria multiply at temperatures below 50°/55°C (122°/131°F).
You have to decide for yourself.
b) high storage temperatures or regular legionella control program
c) instantaneous water heater
In a single-family home, the risk does not seem very high, but legionella bacteria multiply at temperatures below 50°/55°C (122°/131°F).
You have to decide for yourself.
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