Photovoltaic system offer for our single-family house

You mean yield? Let me guess: north roof, northern Germany. Then yes

Even for E/W here, pvgis (5% system loss) only gives me 830 kWh/kWp.

But for me it will probably be a bit lower since I have shading during the first 3 hours of the day.

So the answer is: it depends.

You mean yield? Let me guess: north roof, northern Germany. Then yes

Yes, exactly yield
Western Germany, NRW 46562, 8 kWp southeast almost south, 4.2 kWp northwest almost north
Here again the data from pvgis, I hope everything is correct
Southeast side with 8 kWp

Horizon:;Calculated

Database used:;PVGIS-SARAH2

Photovoltaic technology:;Crystalline silicon

Photovoltaic installed [kWp]:;8

System loss [%]:;14

Simulation outputs:;

Slope angle [°]:;45

Azimuth angle [°]:;-43

Yearly Photovoltaic energy production [kWh]:;7868.2

Yearly in-plane irradiation [kWh/m2]:;1227.95

Year-to-year variability [kWh]:;415.67

Changes in output due to:;

Angle of incidence [%]:;-3

Spectral effects [%]:;1.8

Temperature and low irradiance [%]:;-5.68

Total loss [%]:;-19.91

Photovoltaic electricity cost [per kWh]:;0.158

Northwest side with 4.2 kWp

Horizon:;Calculated

Database used:;PVGIS-SARAH2

Photovoltaic technology:;Crystalline silicon

Photovoltaic installed [kWp]:;4.2

System loss [%]:;14

Simulation outputs:;

Slope angle [°]:;45

Azimuth angle [°]:;137

Yearly Photovoltaic energy production [kWh]:;2339.44

Yearly in-plane irradiation [kWh/m2]:;734.48

Year-to-year variability [kWh]:;59.11

Changes in output due to:;

Angle of incidence [%]:;-5.36

Spectral effects [%]:;1.55

Temperature and low irradiance [%]:;-8.25

Total loss [%]:;-24.16

Photovoltaic electricity cost [per kWh]:;0.533

Smartmeter yes - it's simply fun when you see what the system is doing. It also helps with optimization, if you feel like it.

Otherwise: regular taxation!

And 800 kW/kWp is ok. That is the German standard for E/W systems. One should build up to 600, south roofs usually reach 1000.

Smartmeter yes - it's just fun to see what the system is doing. It also helps with optimization, if you feel like it.

I have a digital electricity meter, I already read it out via the IR interface and evaluate it via ioBroker. It is a two-way meter, so I can also see what is currently consumed. I'll probably leave out the SmartMeter for now.

Good day everyone,

I am the creator of this thread and wanted to post an update. I have received a second offer from a solar installer who was recommended by one of my future neighbors.

He offered the following: €12,500 net for 11 kWp. This fully covers the south roof (25° pitch).

The following will be used:
27 x JinkoSolar solar module Tiger NE HC N-Type sw JKM410N-54HL4-B
1 x SMA inverter STP10.0-3SE-40
1 x SMA Sunny Home Manager HM-20

Optionally, there is a BYD B-Box Premium HVS 7.7kWh for €5,900 net.

I spoke with him again today and he now also offers to optionally install modules on the north roof.

What I have learned here: storage is not worth it, the north roof at 25° should definitely be fully utilized :-D

Is this still true? The price for the storage is relatively good. Of course, the price for the system itself is amazing.

Financially, it is unfortunately not an option for us to fully cover both north and south roofs and then add storage. So the consideration is either the 11 kWp for the south roof plus storage and possibly 3-4 kWp on the north, or fully covering both roofs and leaving out storage. (and possibly retrofit later)

Fully covering the roofs would also have the advantage that we could save on the tile roofing and just do a metal roof. But I still have to ask the general contractor what discount he would give for that financially.

What do you think? Any ideas / tips?

Thank you in advance!

In my opinion, a simple decision. North plus south roof fully utilized (also because of the 70%). The SMA would have to be a hybrid inverter, BYD battery later retrofittable.

Personally, I would currently go further and borrow money to install the battery directly. I now think it pays off. Wallbox?