Operate heat pump autonomously with photovoltaic system.

In Spain it is a poor value, here in this country it is already upper average. You heat the most when it is cold, and then the Cop is also worse..

from on the go

@ : I have now gone through the thread from the beginning and I have a question regarding the powerwall. I myself have had a photovoltaic system on the roof since 2013 but no storage. How much did you effectively pay for the storage and how much for your system? I have calculated it for myself and I don't see any profit from the storage. It would be great if you could be specific. Thanks in advance...

He calculated as follows: he is doing KFW40, so the Plus package is also worthwhile. Under these conditions, that may be true. But KFW40 is not economical from the outset. So if you calculate from the beginning, you end up with the Energy Saving Ordinance standard or KFW55, and the surcharge for KFW40 and the Plus package is then very high.

There are treatises about at which storage price it becomes profitable.. I believe around 800 € per kWh... currently it rarely goes below 1000 €. Just google it. 200 cycles per year with e.g. 5 kWh --> 1000 kWh * (24.8 - 12.5) cents = 123 € per year. 6000 cycles in its lifetime correspond to about 3690 € ~ --> Max. 800 € per kWh including EVERYTHING (installation, maintenance, insurance over the lifetime)

: that's exactly the problem I have. I just wanted to know how much the storage costs and how much the photovoltaic costs. that this whole thing and even better insulation stuff is portrayed like this due to extreme lobbying by the insulation industry is clear to me, I’m not playing that game in that form either. I’m seeing it right now with an acquaintance. he is also building such a unit. he has construction costs of €2,700/sqm (after deduction of all subsidies!!!) and no, he doesn’t have golden faucets in there.... with 3 kids, I think the focus was elsewhere. but that wasn’t the question anyway.

There are treatises about from which storage price it becomes profitable.. I think around 800 € per kWh... rarely below 1000 € nowadays. Just google it. 200 cycles per year with e.g. 5 kWh --> 1000 kWh * (24.8 - 12.5) cents = 123 € per year. 6000 cycles in its lifetime correspond to 3690 € ~ --> Max. 800 € per kWh including EVERYTHING (installation, maintenance, insurance over the lifetime)

You are now assuming that the storage lasts for 30 years? Cool...

With my smartphones, losses are already noticeable after one year.

We have a price of 0.257 EUR per kWh. Of that, 0.041 EUR VAT which applies anyway, so 0.216 EUR per kWh net. For 0.1231 EUR per kWh you feed in - so you lose that with self-consumption. As far as I understand, you still have to declare it as a withdrawal in kind, so income tax is due on it one way or another.

This leaves a difference to grid electricity of 0.216 - 0.1231 = 0.0929 EUR/kWh.

Even if the storage were free, 100 percent efficient and you did everything via storage, 4,000 kWh, that would easily suffice for electric and heat pump in our case, then you could save 0.0929 x 4,000 kWh = 371.60 EUR per year.

Okay, Tesla Powerwall has 92% efficiency, so 8% losses. That's another 1.1 cents lost (calculated on the 12.31 euro feed-in, which is lost). So there remains a difference of 0.0819 EUR per kWh.

If the Tesla Powerwall has 6.4 kWh and 5,000 charge cycles, that is 32,000 kWh stored and delivered again. To maintain the difference to grid electricity, the storage including interest, maintenance, installation and all the administrative effort (everyone can calculate that for themselves; 4h per year at 25 EUR = 100 EUR per year administrative cost; well, no craftsman would get up in the morning for 25 EUR to lay a heating pipe or a tile, but let's stay in the dumping segment for this calculation) ... could cost 2,620.80 EUR. Strictly speaking, capacity decreases over time, probably from 100 percent to 80 percent? Then we calculate with 90% of the costs (100-80 = 90 percent on average): 2,358.72 EUR.

So obviously you have not made any profit yet. 5,000 charge cycles are about 250 cycles per year and 20 years. If I aim for a profit of 2,000 EUR in these 20 years, then the Powerwall could still cost me: 358.72 EUR.

But even for 360 EUR this thing would not be economical, because all administrative costs etc. already exceed the possible profit.

But if you consider it a technical gadget, then you buy the thing for 5,000-6,000 EUR, save 2,000 EUR over 10-20 years with it and book the remaining 3,500 EUR as a gadget and that's it. I don’t want to stop anyone from doing that. It’s a nice gadget, really.