Vestaxx window heating - experiences?

Oh , now you're hitting him again with such nasty numbers.
Don't you know that you just haven't understood it correctly? You just have to watch the webinar, then everything will be clear! :D

5400*(35+35*1.06^18)/2+600*8.2=3,691€/year

To no goal or just not to your goal?
With concrete change proposals (including justification), I am happy to remain available.

I scrolled through again, so far I could only find this:


Yes, photovoltaics were already included, household electricity in the relevant period as well, but I will gladly mark it again in red for you:

150m² with 40kWh/m²a -> 6000kWh/a heating energy demand
10kWp photovoltaics + 5kWh storage -> ~15kWh/day in Nov, Dec, Jan, Feb. With 10kWh for household electricity including hot water, 5kWh/day remain for heating
The costs of photovoltaics are not listed in this example because the system pays for itself through feed-in tariffs and savings on household electricity.
I leave out hot water costs each time since both systems can provide it with COP4 and therefore it makes no difference; the electricity for hot water is included in the household electricity calculation.
Electricity purchase price 35ct/kWh
Feed-in tariff price: 8.2ct/kWh
Interest 3.5% (current interest for 10-year fixed term)
Electricity price increase 6% (average of the last 20 years)

Vestaxx + Photovoltaics:
Surcharge over normal windows: €10,000
Purchase and installation of BWWP: €5,000
Interest on purchase over 18 years: €5,239
Maintenance BWWP: €200/year
4 [months] * 30 [days] * 5 [kWh/day] = 600 [kWh] from photovoltaic electricity
Remaining 5400kWh as purchase
Totals (average, due to rising electricity prices) 5400 * (35 + 35 * 1.06^18) / 2 + 600 * 8.2 = €3,691/year
After 18 years that makes: €90,286

Heat pump + Photovoltaics:
Hydraulics: 80€/m² * 150m = €12,000
Purchase air-water heat pump monoblock and installation: €20,000
Interest on purchase over 18 years: €11,176
Maintenance air-water heat pump: €250/year
Electricity demand: 6000 / 4 = 1500kWh
Remaining 900 to be purchased
Totals (average, due to rising electricity prices) 900 * (35 + 35 * 1.06^18) / 2 + 600 * 8.2 = €656/year
After 18 years that makes: €59,488

Vestaxx without Photovoltaics:
Surcharge over normal windows: €10,000
Purchase and installation of BWWP: €5,000
Interest on purchase over 18 years: €5,239
Maintenance BWWP: €200/year
Totals (average, due to rising electricity prices) 6000 * (35 + 35 * 1.06^18) / 2 + 600 * 8.2 = €3,691/year
After 18 years that makes: €94,558

Heat pump without Photovoltaics:
Hydraulics: 80€/m² * 150m = €12,000
Purchase air-water heat pump monoblock and installation: €20,000
Interest on purchase over 18 years: €11,176
Maintenance air-water heat pump: €250/year
Electricity demand: 6000 / 4 = 1500kWh
Totals (average, due to rising electricity prices) 1500 * (35 + 35 * 1.06^18) / 2 = €1011/year
After 18 years that makes: €65,878

This results in additional costs for Vestaxx of €30,798 in this example compared to the heat pump.
So for 18 years, paying €142 more per month without having the underfloor heating at the end of the term!
All the money is gone to the energy supplier and largely converted into CO2.

Sorry, I'm a bit late to the party and am just trying to understand the formula. I (still) don't have photovoltaics on the roof and am not particularly skilled in economic calculations. , why are you adding 600 kWh of feed-in tariff on top, which you previously accounted for as self-consumption in the electricity demand? A kilowatt-hour produced by photovoltaics cannot be both self-consumed and sold at the same time, can it!? Besides that: shouldn't the feed-in tariff be subtracted instead of added (because it's income, not expenses)? I'm a bit lost here.

a storage system comes into play and static earnings values are calculated

Suddenly continuous text and no more tables.

The discussion leads to no end - so I am ending it from my side now

Why do you add 600 kWh of feed-in tariff on top, which you previously claimed as self-consumption for electricity demand? A kilowatt hour produced by photovoltaics cannot be both self-used and sold at the same time, can it!? Apart from that: shouldn’t the feed-in tariff be subtracted instead of added (because income, not expenses)? I am currently confused.

The calculation is unfortunately completely wrong just for the reason that he completely leaves out the total earnings from photovoltaics in Vx + photovoltaics and only takes the yield that can be used directly for heating in winter. Everything else generated by photovoltaics - simply omitted

Both help your version, as I explained above. So very fairly calculated by

That should be to your advantage? The one with the tables was .

Too bad, I would have liked to know what you think about my thesis regarding the target group.

Read your own text again very slowly. You answered your question yourself. He adds the (lost) feed-in tariff to the costs. Economically exactly right, since it is not a cash flow consideration.

No, not omitted. He writes exactly what he does with it, namely paying for the photovoltaics in both versions.