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 =)
Thanks for your tip. The possible expansion of the system is, of course, logical and the result understandable. However, economic efficiency is my top priority, so it is not an option for me. That said, I have also been considering a wind turbine. It operates most efficiently, especially during the months mentioned. Another idea was an additional pellet-fired combined heat and power unit. It will definitely be a BYD Pro Hybrid by Fenecon.
oleda222 schrieb:
I'm curious to see how you will reconcile your demand for cost-effectiveness with building a new house. The heat generator is probably just the last point of inefficiency, not to mention KfW40plus... I don’t quite understand. Did you just claim that KfW 40 Plus is uneconomical?I would even argue that building a single-family house, occupied by only one family, is inherently uneconomical.
Therefore, your statement cannot be correct or is disingenuous:
Therefore, your statement cannot be correct or is disingenuous:
Inotsara schrieb:
Doch bei mir steht Wirtschaftlichkeit an oberster Stelle.
Although the cost-effectiveness could surely be debated for much longer now:
You essentially pay for the savings in electricity/heating energy with money or capital. The necessary investments are already noticeably high. If you have the money, you face the opportunity cost of the interest (currently low). If you have to borrow the money, you pay interest...
However: If I had the money (meaning in the bank, not borrowed), something like this would definitely be in my focus. Because some people simply enjoy it. Me too. I would forego the interest on the capital portion in favor of the resulting project and enjoyment and make the investment.
A combination with a small 1.5 kW wind turbine would personally appeal to me as well. For example, my house is located in a very wind-exposed spot, especially in autumn/winter/spring, where the unit would probably operate 75% + x of the time.
Complete energy self-sufficiency is not realistically achievable in our regions at reasonable costs. The storage capacities required for this are unfortunately not affordable at present. But achieving rates of 70–80% over the year is, in my opinion, already a really great achievement.
I would be thrilled to have something like that.
For me, the scale is much smaller: I hope to reach about a 45–50% self-consumption rate for electricity with the photovoltaic system and 2 kWh storage coming this spring. If I manage that, I will already be very happy.
You essentially pay for the savings in electricity/heating energy with money or capital. The necessary investments are already noticeably high. If you have the money, you face the opportunity cost of the interest (currently low). If you have to borrow the money, you pay interest...
However: If I had the money (meaning in the bank, not borrowed), something like this would definitely be in my focus. Because some people simply enjoy it. Me too. I would forego the interest on the capital portion in favor of the resulting project and enjoyment and make the investment.
A combination with a small 1.5 kW wind turbine would personally appeal to me as well. For example, my house is located in a very wind-exposed spot, especially in autumn/winter/spring, where the unit would probably operate 75% + x of the time.
Complete energy self-sufficiency is not realistically achievable in our regions at reasonable costs. The storage capacities required for this are unfortunately not affordable at present. But achieving rates of 70–80% over the year is, in my opinion, already a really great achievement.
I would be thrilled to have something like that.
For me, the scale is much smaller: I hope to reach about a 45–50% self-consumption rate for electricity with the photovoltaic system and 2 kWh storage coming this spring. If I manage that, I will already be very happy.
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