Vestaxx window heating - experiences?

I am now playing Advocatus Diaboli and say: The heat pump is missing maintenance/repair plus replacement.

However, this is manageable over the service life - unscrew the old heat pump from the pipes (in the example with monoblock even possible on-site) and screw on the new one. It is an effort of more than generously half a day plus a new monoblock. If we take a small monoblock for the heating load, it will still be well below €10,000 including inflation in 10-15 years. Maintenance will be just as intensive as with the domestic hot water heat pump – so it is a draw in both cases. The domestic hot water heat pump will also need to be replaced.

I also find the thesis "the other system breaks down, ours doesn't" pretty bold. ;)

I googled a bit about the topic. The "inventor" of the system apparently comes from the field of thin-film photovoltaic module development and has experience sputtering float glass (yes, correct, not tempered glass) with metal and heating it without getting the expected stress cracks. But despite the embedded (if I sputter a surface, is that then embedded?) metals, glass can still break or the only a few micrometers thin layer can get interruptions due to expansion/contraction (that was also an argument for a possible defect of the underfloor heating pipes). Reliable figures have been withheld from me so far. Whether out of lack or intent, I don't know? But they might still come ;)

What is wrong with the calculation:

Both heating systems, separately, have: acquisition costs, ongoing maintenance costs, ongoing operating costs, and a lifespan.
One can establish and compare an overall cost calculation for these – independent of a photovoltaic system.
The lower purchase price of the window heating is already taken into account within the acquisition costs.

If the system does not pass this comparison, it did not pass it.
I cannot and should not include a photovoltaic system in this calculation, and if I do, then I should include the photovoltaic system for BOTH systems – both the costs and the savings effects. Or for NEITHER system.

Creating a comparison between a heat pump system VS a window heating system with photovoltaics is gaslighting, naive calculation, marketing nonsense, call it what you want. In any case, the comparison is flawed.

Okay – first of all -> the windows have NO maintenance costs. And actually nothing can really break because nothing moves. But whatever.

Comparisons of heating systems – or better said – heat generators including distribution can be made. Every direct electric heater loses here. I have already written this several times and it is clear to everyone WITHOUT further calculations. COP 0.95 versus / COP 4 or 5. Does the comparison make sense? For you and others yes, and for people who want to build new and are interested in a heating system, clearly not.

The price makes the difference. If you get a heat pump for 40,000 €, then you can still use the rest of the money for our glass panels and the groundwater heat pump (BWWP), and afford a photovoltaic system. And this photovoltaic system then reduces your household electricity costs.

Of course, you can compare both SYSTEMS and add a photovoltaic system to the heat pump – then please also add the same system on top for the other system. Only then is it a fair comparison.

And why is THAT comparison not naive calculation? It is also strange that every customer (and the energy consultants and professors) immediately understand me. They do not say "... you can’t calculate it like that ...".

Now just imagine you want to build new and money is tight. But you need a heating system. Oil and gas are ruled out. The heat pump including underfloor heating with acquisition costs of 40,000 € remains. Then some nutcase comes along and says: For that money, you get a direct electric heater from us and with the difference, you can still afford a BWWP and a large photovoltaic system.

What is more economical?
The heat pump saves approx. 2,000 kWh annually in a new-built house with approx. 3,000 kWh HWB. That makes 40,000 kWh in 20 years. The user only has to buy 1,000 kWh per year (see your example). That is really good.

With direct electric heating, the user has to buy 3,000 kWh per year and the difference is then 100,000 kWh in 20 years.
That is rather bad. But the photovoltaic system generates a total of 240,000 kWh of free electricity in that period. And is therefore more economical.

If you now add the photovoltaic system you want for the heat pump also to the photovoltaic system of the direct electric heating, you can also compare them again, but the difference will not change.

Or simply:
The customer only has 40,000 € left and wants to pay as little as possible annually for all his energy. Which system is better?

Because it is financially very inaccurate. You argue with saved costs = lower investment. Whether you put the difference into photovoltaics or ETFs or simply into consumption would have to be evaluated separately from a financial perspective. Because it is not a system, it would only be one if, so to speak, the inner pane contains the heating and the outer one a photoactive cell, which is still transparent to fulfill the main function of the window. The fact that it is not technologically one system makes it marketing.

I am comparing two systems that have exactly the same costs and look at what comes out in the end. And that is financially very inaccurate. Sorry, but that is basically completely wrong. Why does the system— to be financially correct— have to produce electricity on the outer pane (which in turn is completely uneconomical)?

And actually, nothing can break because nothing is moving. But whatever.

Ah, that only things that move can break was actually clear, no one else has come up with that yet! I have to explain that to my SSD immediately, which gave up a few days ago!

Comparisons of heating systems - or rather - heat generators including distribution can be made. Every direct electric heating loses there. But I have already written that several times and it is clear to everyone WITHOUT further calculation. COP 0.95 versus COP 4 or 5. Does the comparison make sense? For you and others yes, and for people who want to build new and are interested in a heating system, no.

Yes, absolutely right, the comparison of heating systems only makes sense if you add photovoltaics to one and not to the other. It would be super unfair if the heaters had to heat efficiently on their own in the comparison.

The price makes the difference. If you get a heat pump for €40,000, then you can still use the remaining money for our glasses and the BWWP and afford photovoltaics. And this photovoltaics will then reduce your household electricity costs.

Yes, that also makes total sense the hundredth time I read it, because banks and credits unfortunately have not yet been invented and therefore photovoltaics + heat pump is absolutely impossible.

Of course you can compare both SYSTEMS and add photovoltaics to the heat pump - then please also add the same system on top of the other system. Only then is it a fair comparison.

Scroll up and read.

And why is THAT comparison not a simplistic calculation? It is also strange that every customer (and the energy consultants and professors) immediately understand me. They don’t say "... you can’t calculate it like that ...".

How was it, not everything that limps is a comparison?! Show our arguments and calculations to the energy consultants and professors. Even if it is not their field, hopefully they will be able to understand it.

The customer only has €40,000 left and wants to pay as little as possible annually for all his energy. Which system is better?

Also just scroll up a bit or go back pages and read/recalculate. Spoiler: in the example Vestaxx was over €30,000 more expensive.

Because it is fundamentally inaccurate from a financial science perspective. You argue with saved costs = lower investment. Whether you put the difference into photovoltaics or ETFs or simply into consumption would have to be evaluated separately from a financial science perspective. Because it is not a system, it would only be a system if the inner pane included the heating and the outer one a photoactive cell, which is still transparent to fulfill the main window function. The fact that it is not technologically a system makes it marketing.

I compare two systems that have exactly the same costs and see what comes out at the end. And that is fundamentally inaccurate from a financial science perspective. Sorry, but that is basically completely wrong. Why must the system — to be financially correct — produce electricity on the outer pane (which, in turn, is completely uneconomical).

First of all, we have been talking about your profitability calculation Vestaxx vs. heat pump all the time. I am actually not willing to read a page of continuous text but want to see proper tables. Secondly, we are talking about spreadsheet software aka Excel, Open Office, etc. No one here wants to see your software, but only properly prepared profitability calculations of the systems window heating vs. heat pump at current seasonal performance factors of 4–5. Yes, just like me. See point above. I already broke it down. Here is the old excerpt: CO2e for German steel assumed about 2.5kg, PE floor pipes 17x2 with 2kg CO2e. Production overhead is calculated at a flat 25%. Copper pipes and heat exchangers are actually significant CO2 emitters again. Let’s add another 100kg. Fortunately, aluminum is light. The few valves and heating circuit distributors do not weigh much. Of course, problematic is the CO2e of the German grid mix. Before the war there were ambitious targets, which I now strongly doubt since East German brown coal power plants have started up again. I simply assume our government will reach the <25% of 1990 target only 10 years later in 2040. In the respective columns then electricity consumption/a*CO2e/kWh. When summed up over the observation period it looks like this: One must of course also consider Scope 3 downstream and not only Cradle to Gate. Infrared is even here in the forum the go-to solution e.g., here in the bathroom for additional heating if the heating surface is not large enough. But that’s not what this is about.

YOU wrote business case and I read business case — if you mean profitability calculation, then just write that. -> whatever. With ETFs I don’t know what comes out at the end (risk and opportunity -> speculation). Consumption is also possible. There I know the money is gone and I had a little pleasure. With photovoltaics I know very exactly what comes out within the lifetime. -> security Now about your table. Fine — you don’t like reading continuous text (with numbers and formulas) and I don’t like any tables where I have to work out the formulas myself. So everyone has their preferences — whatever. The first mistake is to assume a continuous seasonal performance factor of 3 for the BWWP. It is definitely higher — also whatever. Your table is great — thanks for that. One can see very clearly that the seasonal performance factor plays a role and with the seasonal performance factor of 5 we are about even after 15 years. What is unfortunately missing are maintenance costs — with us zero and for the heat pump? €200 yearly? I don’t know right now. What you calculated so far is what comes out after 15 (20 years) if the customer uses the saved money to pay the electricity costs. Another — but very important — component is electricity price increases. And now again — I know it’s annoying — the consideration that the customer is clever and chooses security. With the purchase of a photovoltaic system (with the saved investment costs) he does exactly that. Photovoltaics are good — we all agree here. But then we can forget your table again and need a new one that considers that. The customer makes himself largely independent from the certainly still rising electricity prices with a large photovoltaic system. That is what moves people. CO2 consideration -> also thanks for the table, but just looking at the CO2 during production and then leaving something out again is not helpful. Also way too many numbers — sorry! Put differently. I can easily hold our material for the heating technology of an entire house in one hand. With water-based systems you need a heavy forklift. Does that make sense? “... One must of course also consider Scope 3 downstream and not only Cradle to Gate ...” Who among the normal people who want to find out about window heating here understands such a sentence? Write understandable German or just leave it out.