ᐅ Operating a heat pump independently with a photovoltaic system.
Created on: 18 Dec 2015 19:51
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Inotsara
Is there a photovoltaic expert here? Preferably an engineer specializing in this field? I am an electrician myself but have not yet had any practical experience with photovoltaic systems. So far, I only know about them theoretically and am very enthusiastic. I want to dive deeper into this topic and prepare myself for practical work. Recently, I have been looking into inverters and especially battery storage. The more I read, the bigger the gap I feel needs to be filled.
Currently, I am working on a project involving my parents' air-to-water heat pump. It’s a newly built house with two living units. The combined electricity consumption of both units is about 2200 kWh. Additionally, the pump consumes approximately 6600 kWh per year. Naively, I assumed my parents could invest around 25,000€ in a 9 kWp photovoltaic system and achieve a self-sufficient setup with very low electricity costs (about 30€ per month instead of 180€).
But that’s not the case. Firstly, a single-phase storage system is not an option because, due to the technology and grid regulations, the pump relies on the other two phases and will ALWAYS draw power from the grid. Even with a three-phase battery storage system, this problem would only be theoretically circumvented but not completely solved. Especially in winter, the pump runs at 80%-100% capacity while a photovoltaic system generates only about 30%-35% of its output in winter. In summer, the situation is almost exactly the opposite. This means we would underproduce in winter and overproduce in summer. On top of that, a three-phase battery system costs twice as much, and the number of manufacturers offering this option is very limited.
So, my question to the real experts: Should I just discard the idea of making the heat pump fully independent, or have I missed something?
I have gained a lot of knowledge in recent days through phone conversations with an engineer who is also a salesperson. However, I feel a bit uncomfortable bothering him further. He has already explained a lot to me. Also, information in written form is always better because you can look things up repeatedly and add to your knowledge. Therefore, it would be great if we could share our knowledge here together =)
Currently, I am working on a project involving my parents' air-to-water heat pump. It’s a newly built house with two living units. The combined electricity consumption of both units is about 2200 kWh. Additionally, the pump consumes approximately 6600 kWh per year. Naively, I assumed my parents could invest around 25,000€ in a 9 kWp photovoltaic system and achieve a self-sufficient setup with very low electricity costs (about 30€ per month instead of 180€).
But that’s not the case. Firstly, a single-phase storage system is not an option because, due to the technology and grid regulations, the pump relies on the other two phases and will ALWAYS draw power from the grid. Even with a three-phase battery storage system, this problem would only be theoretically circumvented but not completely solved. Especially in winter, the pump runs at 80%-100% capacity while a photovoltaic system generates only about 30%-35% of its output in winter. In summer, the situation is almost exactly the opposite. This means we would underproduce in winter and overproduce in summer. On top of that, a three-phase battery system costs twice as much, and the number of manufacturers offering this option is very limited.
So, my question to the real experts: Should I just discard the idea of making the heat pump fully independent, or have I missed something?
I have gained a lot of knowledge in recent days through phone conversations with an engineer who is also a salesperson. However, I feel a bit uncomfortable bothering him further. He has already explained a lot to me. Also, information in written form is always better because you can look things up repeatedly and add to your knowledge. Therefore, it would be great if we could share our knowledge here together =)
f-pNo schrieb:
I just came across this post.
Do you really think anyone will care in 20-30 years which energy standard a house was built to?
I believe the question won’t be asked (as it isn’t today) and it won’t have much impact on the selling price of the property.Hi!
Thank you for your comments.
I think you are quite right regarding the 20-30 year timeframe.
However, seeing that from 2021 only passive houses are allowed to be built, I assume people do care about the energy standard.
Whether this will significantly affect the purchase price, I cannot say. In 30 years, it won’t matter much to me either. By then I will be 80, and since we have no children, accumulating wealth won’t be a priority.
I suspect this will remain an important factor over the next 7-12 years. But we will see.
Thanks again and best regards,
Thorsten
T21150 schrieb:
Hi!
Thank you very much for your words.
I think you’re quite right regarding 20 to 30 years. However, since 2021 only passive houses are allowed to be built, I assume people are already interested in the energy standard.
Whether this will have a significant effect on the purchase price, I can’t say. In 30 years, I won’t really care. I’ll be 80 then, and we (childless) don’t need to accumulate wealth anymore.
I suspect this will still be an important factor over the next 7 to 12 years. But we will see.
Thanks again and best regards,
ThorstenAs for me, I can only speak for our experience. We looked at a few used properties that were also advertised as very energy efficient. But the bills told a different story. In the end, we decided on a new build to KfW 40 standard. For us, efficiency was the decisive factor. But I think this varies from person to person.
Inotsara schrieb:
I will work on this soon and gladly post the link here. It’s more worthwhile now than ever…So – I’ve had a photovoltaic system plus a small battery storage installed for 5 weeks now, basically what could fit into the utility room.
Because I like it. It also works absolutely excellently.
At the moment: It simply doesn’t pay off financially (not enough to be impressive). But that doesn’t matter, because I definitely wanted something like this. Just a gut feeling.
Currently, I’m fine as long as my costs roughly break even with what I pay for electricity from the grid. I think that’s about right, apart from maybe plus or minus 10 euros per month.
I also share (just from a gut feeling) your view that we will very likely see electricity prices around 40 cents per kWh. Reasons:
- phase-out of coal
- shutdown, decommissioning, and final disposal of nuclear power plants
- expansion of the grid (HVDC grids, local grids)
- in about 5 years, many wind turbines will need to be replaced, and in 7–9 years the first large solar parks will require renewal
- and much more. We’re talking about several hundred billion euros in total costs over the next 15 years (rough estimate). Naturally, this will be passed on to consumers.
You’re not allowed to post a link here.
Please be so kind and send me the link via private message. I’m very interested in this topic and also in exchanging ideas about it. Thanks.
Best regards
Thorsten
T
toxicmolotof10 May 2016 00:42By monthly costs, I mean either the loan payment or, if self-financed, the depreciation (Afa).
The additional costs need to make financial sense.
And where does the repayment subsidy come from? Probably from KFW153, but then you also have to factor in the extra costs for insulation, heating, etc. Or from the subsidy for the storage system... but then your own "electricity price" seems surprising to me.
If your own kWh costs 27 cents, does that already include VAT and the taxation of the non-cash benefit from the commercial operation?
Furthermore, you mentioned only 200 euros in electricity costs per year... your own electricity also comes at a cost. (see above)
I stand by my statement, especially since I also calculated my system back in January.
The additional costs need to make financial sense.
And where does the repayment subsidy come from? Probably from KFW153, but then you also have to factor in the extra costs for insulation, heating, etc. Or from the subsidy for the storage system... but then your own "electricity price" seems surprising to me.
If your own kWh costs 27 cents, does that already include VAT and the taxation of the non-cash benefit from the commercial operation?
Furthermore, you mentioned only 200 euros in electricity costs per year... your own electricity also comes at a cost. (see above)
I stand by my statement, especially since I also calculated my system back in January.
A
Andre-Jana6 Jun 2016 23:47Hello everyone.
I am currently planning to build a house as well. I am wondering whether to build a KfW Efficiency House 55 or to stick with the standard requirements.
The house will be built in an urban villa style, which means
- two full floors,
- no basement,
- exterior dimensions approximately 10.5x10.5m (34x34 feet),
- ground drilling not possible due to rocky soil!
Is the extra effort (higher costs) for different insulation, a heat pump, and photovoltaic system worth it because of the relatively low-interest KfW loan and subsidies? (100,000€ at about 1.3 percent over 20 years)
Can you even make a general statement about this? I would appreciate hearing some opinions here. Also, any tips are welcome.
I am currently planning to build a house as well. I am wondering whether to build a KfW Efficiency House 55 or to stick with the standard requirements.
The house will be built in an urban villa style, which means
- two full floors,
- no basement,
- exterior dimensions approximately 10.5x10.5m (34x34 feet),
- ground drilling not possible due to rocky soil!
Is the extra effort (higher costs) for different insulation, a heat pump, and photovoltaic system worth it because of the relatively low-interest KfW loan and subsidies? (100,000€ at about 1.3 percent over 20 years)
Can you even make a general statement about this? I would appreciate hearing some opinions here. Also, any tips are welcome.
From my own experience, I can say that a bank’s approval for a KfW loan is not guaranteed. For example, our bank rejected the KfW 124 loan in order to proceed with financing. Additionally, our request for the KfW 153 loan with a 10-year term at 0.75% interest was also declined. We had to accept a 20-year term at 1.5% interest instead.
Whether the KfW 55 standard is worth it in the long run is something you need to decide for yourself. Calculate it over 30 to 40 years and consider how much you could save on additional costs, including maintenance and repairs. I believe it is always beneficial to build for the future. In 30 years, our KfW 40 Plus home will likely sell better than a KfW 70.
Whether the KfW 55 standard is worth it in the long run is something you need to decide for yourself. Calculate it over 30 to 40 years and consider how much you could save on additional costs, including maintenance and repairs. I believe it is always beneficial to build for the future. In 30 years, our KfW 40 Plus home will likely sell better than a KfW 70.
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