ᐅ Operating a heat pump independently with a photovoltaic system.
Created on: 18 Dec 2015 19:51
I
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 =)
oleda222 schrieb:
W
I would still be interested to know how you calculate your KfW40+ house so nicely.Not to get personal, but may I ask what happened to you? It seems like you had a personal experience with this, right? Did you build with solid construction, or why do you have such a lack of interest in KfW 40 Plus? Once you understand the concept, there really shouldn’t be any objections.Inotsara schrieb:
It's a pity that the thread missed its purpose.No, the thread did not miss its purpose.
We can sum it up briefly and leave it at that.
Thorsten
Inotsara schrieb:
Without meaning to get personal, may I ask what happened to you? It seems like you had a personal experience, right? Did you build with solid construction, or why do you have no interest in KfW 40 Plus? Once you understand the concept, there shouldn’t really be anything against it.From my point of view, there are many reasons to support energy efficiency and careful use of resources, and I think it’s great when someone builds to KfW55/40/40+ standards.
I also don’t know where you get the idea that I’m not interested in KfW40+. Does it say that anywhere?
Against it speaks
Inotsara schrieb:
For me, economic efficiency is the top priority.Feel free to convince me otherwise! I would be thrilled if I’m wrong.
I am building a timber frame house, KfW55, ground-source heat pump, and controlled ventilation with heat recovery, etc., etc. I like the concept, but from today’s perspective, it is economically nonsensical. The construction costs are high compared to a house built to the Energy Saving Ordinance, and the savings in heating costs with current electricity/gas prices are ridiculously low.
Inotsara schrieb:
I don't understand how anyone can insist on the opinion that a house is not economical. Nowhere did I claim that any house is uneconomical, but rather a typical single-family home that is occupied by an average family alone.
In my opinion, living in more than 100 sqm (1,076 sq ft) is not economical. It is a waste of space and resources.
It might be profitable if you sell it for more than you buy it. It is practical for family life and hopefully fulfilling for the individuals, and certainly serves many other purposes.
But it is not economical.
For me, it doesn’t have to be, but for you, economic efficiency seems to be the top priority...
Hello everyone,
I would like to revisit the topic of KfW 40+ here, even though it differs somewhat from the original subject.
I am currently planning a new build, and the current offer describes a KfW 55 house (140 sqm (1507 sq ft) plus 40 sqm (430 sq ft) basement apartment plus 20 sqm (215 sq ft) finished basement = approximately 200 sqm (2153 sq ft) living area, with an air-to-water heat pump).
Since the house is offered as a KfW 55 standard, I would currently receive a €12,000 grant from the L-Bank. For a KfW 40 standard, there would be an additional €10,000, which according to my provider would cover the extra insulation required. For KfW 40+, there would be yet another €10,000 grant, which would at least allow me to finance a photovoltaic system (~5–6 kW) and maybe a part of the battery storage.
However, since March 1, 2016, there are new guidelines for KfW program 275, but I have found few discussions on this so far, so I have the following questions:
- Is it possible to combine KfW 153 and 275 programs?
- Is a maximum grid feed-in of 50% realistically achievable? What happens, for example, in summer when the grid feed-in might be higher?
- Are common inverters and batteries already designed to meet the new requirements?
- Is the 10-year time-value replacement guarantee already factored in by manufacturers?
I would like to revisit the topic of KfW 40+ here, even though it differs somewhat from the original subject.
I am currently planning a new build, and the current offer describes a KfW 55 house (140 sqm (1507 sq ft) plus 40 sqm (430 sq ft) basement apartment plus 20 sqm (215 sq ft) finished basement = approximately 200 sqm (2153 sq ft) living area, with an air-to-water heat pump).
Since the house is offered as a KfW 55 standard, I would currently receive a €12,000 grant from the L-Bank. For a KfW 40 standard, there would be an additional €10,000, which according to my provider would cover the extra insulation required. For KfW 40+, there would be yet another €10,000 grant, which would at least allow me to finance a photovoltaic system (~5–6 kW) and maybe a part of the battery storage.
However, since March 1, 2016, there are new guidelines for KfW program 275, but I have found few discussions on this so far, so I have the following questions:
- Is it possible to combine KfW 153 and 275 programs?
- Is a maximum grid feed-in of 50% realistically achievable? What happens, for example, in summer when the grid feed-in might be higher?
- Are common inverters and batteries already designed to meet the new requirements?
- Is the 10-year time-value replacement guarantee already factored in by manufacturers?
Similar topics