ᐅ Cost-effectiveness of Photovoltaic Systems and Energy Storage

Hello everyone,

Today, after some side discussions and uncertainty 🙂 , I would like to ask for your help regarding the cost-effectiveness of a current offer. We are building a new house this year. We currently live in a semi-detached house with about 120 sqm (1,292 sq ft) of living space; the new house will have about 220 sqm (2,368 sq ft).

We both work more than 90% from home, with one child.

The roof orientation will be South-South-West.

Electricity consumption in 2021: 3,558 kWh
Heating electricity demand with heat pump in 2021: 3,617 kWh

The new house will have district heating and a centralized ventilation system.

I have a quote from the company enersol for:

Photovoltaic system 9 kWp (maximum capacity for this type of photovoltaic modules according to the dealer)
24 WINAICO WST-MGL GEMINI 375 modules for the heat pump

Fronius Symo 8.2-3-M, 1 unit

sonnenBatterie 10 with 11 kWh (energy storage)

The complete installation, including one year flat-rate insurance, mounting structure, delivery, connection and completion notifications, final acceptance, etc., is included.

Price with storage: 26,296 Euros gross.
Price without storage, including installation but excluding scaffolding flat fee (500 Euros), is 13,447 Euros gross.

Is this worth it?

As far as I have read so far: No. But I'm sure others who are more knowledgeable on the topic will have something to add.

For example, I compare the offered battery with 11 kWh for 13,000 EUR against the Tesla Powerwall with 13.5 kWh for 9,600 EUR. – OK, without installation, but an electrician should be able to come for around 3,500 EUR.

Otherwise, such a large storage system probably isn’t worthwhile anyway. You first have to fill it or empty it. => In winter, you won’t fully charge it during the day, and in summer, you won’t fully discharge it at night.

And in the future, the electricity will probably just go into the electric car’s battery during the day anyway.

1,310 €/kWp net for the photovoltaic system is reasonable for this size, I would say. Not a bargain, but it’s always uncertain if you can find something better at the moment.

Recovering VAT would mean it pays for itself over time. You just have to do the calculations.

Or you could still look for a better deal. The profit depends on the purchase price 😉

I think everything about storage and profitability has already been said. There are even studies on this.

In my opinion, the price is reasonable. Around 1,300 per kWp net is not cheap. We signed for 1,100€ two years ago. But considering the current situation, it's certainly acceptable. Prices will probably only go up.

I would skip the battery storage. It’s not cost-effective yet.

If you plan wisely, you can expect about 30% self-consumption. For average users without a pool, that’s fine, and with heating, even more.

I would go for it.

KingJulien schrieb:

€1,310 per kWp net for the photovoltaic system is reasonable for that size, I would say. Not a bargain, but it's always questionable whether you can get something better at the moment.
If you reclaim VAT, it should pay for itself over time. You just have to do the calculations.

Or you might want to look for a better offer. The profit depends on the purchase price 😉

Regarding storage and profitability, I think everything has already been said. There are even studies available.

Regarding VAT reclaim – does that mean I have to submit monthly advance returns and pay taxes on self-consumption? Does it make financial sense in the long run?
In general: Are there online calculators that calculate everything properly? Including tax-related issues, etc.? Like a complete calculator, so to speak.

Only quarterly now. The year of the commissioning and one more, then you can apply for exemption. I think so, just a rough estimate. Please feel free to correct me if anything is wrong.

It’s really not a big deal, I believe you only need to enter three numbers online.
Over with the PV people, there’s a good Excel program for everything (Paulchens Photovoltaic Tax), including support, available for a donation to a good cause.

VAT on direct consumption is peanuts.
I don’t know your hourly wage, but for me, spending a few hours on tax paperwork pays off with the VAT refund 😉

There is one from Stiftung Warentest. Or simplified as @Deliverer and @Benutzer200 have already calculated.
Since you don’t know some parameters anyway (future electricity price, self-sufficiency rate, lifespan, etc.), this actually makes more sense.
Better a good estimate than a bad calculation!