ᐅ Integration of Air-to-Water Heat Pump, Photovoltaic System, and Energy Storage
Created on: 29 Dec 2019 23:12
A
Appel2000
Hello everyone,
In our new build, an air-to-water heat pump will be installed as the heating system. The system will be installed by our general contractor (GC) or their heating company.
I would now like to have a photovoltaic (solar) system installed on the roof (not through the GC, but by a specialist company that I select myself), with the unused electricity being stored.
The idea behind this is, among other things, to generate part of the electricity needed for the air-to-water heat pump ourselves.
Since I wanted to inform myself a bit before talking to the heating company and the solar company, I searched online. Unfortunately, it wasn’t really helpful.
What I found out is the order in which photovoltaic electricity is used:
1) Current consumers in the house
2) Battery charging
3) Air-to-water heat pump
4) Feeding into the grid
Is this correct so far?
Then you need the technical prerequisites so that the inverter, battery, and air-to-water heat pump can communicate with each other.
Who provides these prerequisites and who usually configures this? The heating company or the solar installer? Are special devices required for this?
When the air-to-water heat pump needs electricity again, the battery should of course be used first before drawing from the public grid. Does this also work if we have a special heat pump tariff?
I would appreciate it if someone could shed some light on this!
Thanks in advance and best regards
A
In our new build, an air-to-water heat pump will be installed as the heating system. The system will be installed by our general contractor (GC) or their heating company.
I would now like to have a photovoltaic (solar) system installed on the roof (not through the GC, but by a specialist company that I select myself), with the unused electricity being stored.
The idea behind this is, among other things, to generate part of the electricity needed for the air-to-water heat pump ourselves.
Since I wanted to inform myself a bit before talking to the heating company and the solar company, I searched online. Unfortunately, it wasn’t really helpful.
What I found out is the order in which photovoltaic electricity is used:
1) Current consumers in the house
2) Battery charging
3) Air-to-water heat pump
4) Feeding into the grid
Is this correct so far?
Then you need the technical prerequisites so that the inverter, battery, and air-to-water heat pump can communicate with each other.
Who provides these prerequisites and who usually configures this? The heating company or the solar installer? Are special devices required for this?
When the air-to-water heat pump needs electricity again, the battery should of course be used first before drawing from the public grid. Does this also work if we have a special heat pump tariff?
I would appreciate it if someone could shed some light on this!
Thanks in advance and best regards
A
Yes, all good ideas. But placing the heat pump during the day – does the sun always shine then? The sun rises, and the photovoltaic system starts producing. The normal consumption is covered. Then the battery is charged with a maximum of 3kW. However, the photovoltaic system generates more than the base load plus battery charging. Then the heat pump begins heating the domestic hot water. So base load plus battery charging plus hot water heating are still less than what the photovoltaic system produces, and the excess feeds back into the grid. The same happens when the battery is full. Or do you think it’s possible to charge a battery with 7-10kW power?!
blackm88 schrieb:
Yes, all good ideas. But: placing the heat pump during the day – does the sun always shine there? No, but the likelihood is higher. Besides, photovoltaic systems work even without direct sunlight.
With an air-to-water heat pump, there is also the advantage of a higher source temperature.
blackm88 schrieb:
The sun rises, the photovoltaic system starts producing. Normal consumption is covered. Then the battery is charged with a maximum of 3 kW. But photovoltaic generates more than base load + battery charging. Then the heat pump begins to heat the domestic hot water. So base load + battery + hot water heating are still less than what the photovoltaic produces, the excess is fed into the grid. The same applies when the battery is full.
Or do you think a 7–10 kW system charges a battery?! It’s not perfect, which is why it’s good that feeding excess energy back into the grid alone already supports the system.
However, you can certainly optimize a bit to use as much photovoltaic electricity yourself as possible.
I have a 6.8 kWp photovoltaic system on the roof. My record this year was 45 kWh in one day, while the total household consumption including hot water was 15 kWh. No matter how you look at it, that amount of energy from the roof can’t be sensibly consumed, even with a battery and overcharging hot water storage.
This is also one reason why batteries are, in my opinion, (still) nonsense. Apart from all the losses, degradation, and maintenance charging in winter... in summer they’re full and idle, in winter they’re empty.
Feeding excess energy into the grid – yes!
H
hampshire31 Dec 2019 14:33guckuck2 schrieb:
One more reason why, in my opinion, storage systems still don’t make much sense. Aside from all the losses, degradation, and maintenance charging during winter... in summer it just sits there full in the corner, and in winter it’s empty. Our "temporary" battery storage, currently 9.6kWh, was repeatedly nearly full around midday this December—which I believe is one of the winter months. Since I haven’t yet connected the monitoring system for detailed analysis (we’re still using provisional inverters), and just check the devices occasionally, I can’t say how many charge cycles it has. I wouldn’t be surprised if the count is over 12. Earlier today, 8kWh were charged into the storage again, while the base load of the house was running. There’s no maintenance charging over winter or it sitting empty. Apparently, you assume there are never any clouds or darkness in summer and no sun in winter. That’s not how I’ve experienced the seasons.
hampshire schrieb:
Our "temporary" battery storage system with a current capacity of 9.6 kWh was repeatedly almost full around midday this December – which I believe counts as one of the winter months. Since I haven’t connected the monitoring system for detailed analysis yet (and the inverters are still provisional), I can’t give an exact number of charge cycles, but I wouldn’t be surprised if it’s over 12. Earlier, 8 kWh were loaded into the battery again, while the house’s base load was running. There’s no trickle charging over the winter or the system standing idle. You seem to assume that in summer there are never any clouds or darkness, and in winter there’s never any sun. That’s not how I experience the seasons.How large is your photovoltaic system?
I live in the west, and even on sunny December days, the roof never produced more than 3 kWh.
But if you’re talking about a 20 kWp system, then that makes sense again.
H
hampshire31 Dec 2019 15:08Nominally 9.99 kWp – 9 W rated power per photovoltaic tile, 1,110 units in total.
How much energy goes into the storage depends not only on the yield but also on the consumption pattern. Our house has a low base load and several appliances that consume a significant amount of electricity when in use. As long as these are not operating, quite a bit of energy flows into the storage.
To the original poster: Such a system is calculated based on the assumptions you make. Then you vary those assumptions and get a range of results to help guide your decision. A battery storage system can be worthwhile or expensive depending on the consumption pattern, which becomes quite clear through this approach.
How much energy goes into the storage depends not only on the yield but also on the consumption pattern. Our house has a low base load and several appliances that consume a significant amount of electricity when in use. As long as these are not operating, quite a bit of energy flows into the storage.
To the original poster: Such a system is calculated based on the assumptions you make. Then you vary those assumptions and get a range of results to help guide your decision. A battery storage system can be worthwhile or expensive depending on the consumption pattern, which becomes quite clear through this approach.
A
Appel200031 Dec 2019 16:15hampshire schrieb:
Such a system is calculated based on the assumptions you make.That’s exactly my problem at first: I have no knowledge and need to study the theory carefully to gain it.
And then, in practice, I try to "optimize" it a bit.
It’s good for me to hear that the charging process of the storage only uses part of the energy, while the rest is consumed as usual.
Thank you all, and I wish you a happy New Year!
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