ᐅ Photovoltaics at Any Cost – Current Situation and Available Options

Created on: 31 Jul 2022 13:22

Hello everyone,

After countless rejections due to overload, availability, and delivery issues, I have finally received an offer for a photovoltaic system.
The system is planned for our new build (completion in 2023). We have a gable roof, almost south-facing, with a 30-degree pitch, fully usable, about 50 sqm (540 sq ft) of roof area per side.
The house is being built in Bavaria, about 60 km (37 miles) from Thuringia.

The offer surprised me a bit. The following items are included:
14x MAXEON modules at 430 W each, heat pump system, totaling 6.02 kWp - €11,138
1x Tesla Powerwall 2.0, 13.5 kWh - €10,400
Installation, etc. - €3,130
Total: €24,668 net

I find that quite expensive. I would leave out the battery anyway, but even then, I think the price for the 6 kWp system is too high. Apparently, this is currently the price you pay in Bavaria if you can find someone at all. For me, the question is whether it even makes sense to invest right now or just pay for electricity. Of course, it’s a matter of calculation, but if you follow the discussions here, those prices seem sky-high — or not?
Is it better to get offers from other regions? Are there any recommendations around the 97XXX area?

i_b_n_a_n23 Nov 2022 13:07

#79

xMisterDx schrieb:

I would be interested to see the calculation that makes a storage system a good investment in summer, especially with 7 kWh for almost 7,000 EUR.
It fills up quickly in summer. And then? Does one typically use 7 kWh at night during summer? Because if I fill the battery once at the beginning of June and then only draw 1-2 kWh at night, it doesn’t make sense.
About two-thirds of photovoltaic energy is generated during the six warm months. In the three mild and especially in the three cold months of the year, photovoltaics at best cover daily demand, and usually do not even do that in the cold months.

Or you install an air conditioning system to consume your own electricity in summer. In that case, you don’t need the battery anymore.

You can also look at the load profile of a heat pump-heated house. You need the most electricity exactly when photovoltaics supply almost nothing anymore.

I live in a small semi-detached house with two units, a ground-source heat pump, and a 4 kWh (4.8 kWh) battery. My electricity consumption (during the period when no generation occurs) averages about 5-6 kWh (5.4-6.5 kWh). So my battery is a bit too small to be optimal for this situation.
During the less favorable season, the battery often fully deactivates itself to avoid running "unfavorable" cycles.

face2623 Nov 2022 13:12

#80

xMisterDx schrieb:

You can take a look at the load profile of a heat pump-heated house. You need the most electricity exactly when the photovoltaic system is barely producing anything.

Yes, that’s true. Often, only about 150 cycles remain. If you disregard the special cases (DIY battery, it fell off the truck according to the brother-in-law, and other jokes), it’s almost impossible to calculate a battery to be economically profitable. Especially not when you base it on current electricity prices.
It becomes particularly difficult with a heat pump because it allows you to shift hot water production to daytime, or in winter you use the photovoltaic output directly anyway—and during transitional seasons, you can even increase consumption in the daytime by planning accordingly.
As a result, the battery cycles per year decrease, extending the payback period. Usually, this becomes a number of years after which you no longer trust the battery to still be effective.
But it always remains a calculation with many unknowns. Just the losses during storage and retrieval cause a lot of debate.
I have done quite a bit of cross-reading in specialized forums over the past few weeks. My conclusion is that if I had invested the money in more solar modules instead of the battery, it would certainly have been more economical. However, profitability was not the sole deciding factor.

RotorMotor23 Nov 2022 13:15

#81

i_b_n_a_n schrieb:

In my small semi-detached house with two residential units, a ground-source heat pump, and a 4 kWh battery, I have an average energy consumption of about 5–6 kWh during periods when no energy is being generated. So my battery is a bit too small to be optimal for this situation. During the colder season, the battery sometimes completely deactivates to avoid unfavorable cycling.

Could you please explain that in more detail? What do you mean by 5–6 kWh from a 4 kWh storage? Is that per day, per week, or per month? What exactly do you mean by a period when “nothing” is being generated? How large is your photovoltaic system?

Tolentino23 Nov 2022 13:18

#82

face26 schrieb:

DIY Battery

Do you have more information regarding the legality or practical issues?

face2623 Nov 2022 13:22

#83

Tolentino schrieb:

Do you have more information here regarding the legality or practical issues?

No, I’ve just read several times that this is being done. But you can find information about it online. This site is not the only one that brings together people interested in a topic for discussion. There is also a platform that deals specifically with the subject of this thread. You can find quite a bit related to your question there.

xMisterDx23 Nov 2022 13:24

#84

Tolentino schrieb:

Do you have more information here regarding legality or practical issues?

The same practical issues you face when driving a homemade car.
No one will approve it, no one will insure it, and if something happens, you are left to deal with the damage and consequences on your own.

ᐅ Photovoltaics at Any Cost – Current Situation and Available Options

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