ᐅ Photovoltaics – Roof Placement and Using a Single Meter?

Created on: 12 Sep 2024 09:59
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Pete1909
Hello everyone!
The photovoltaic topic has now caught up with me as well.
I have ordered 22 modules (10 kWp) plus a battery storage system (10 kW).

1) I would like to ask for your opinion on whether it makes sense to install modules on the back side of the house due to the roof orientation (see photo for orientation).

The sun only reaches that side in the afternoon; the planned roof gets a lot of sunlight from the south, so the battery should be well charged. Does it still make sense to capture the evening sun there? I’m not yet convinced about the added value and whether the gain justifies the effort, especially since the direct side irradiation only occurs in the afternoon to evening hours.

Our consumption is as follows:
Air-source heat pump (water + heating): 3,300 kWh
Household: 2,600 kWh

In the future, an electric car is also likely.

2) Currently, we have two meters (heat pump electricity at 22.67 cents/kWh with €8.15 basic fee; household electricity at 30.49 cents/kWh with €13.84 basic fee).
Does it still make sense to operate with two meters given our consumption? (Additional cost for cascade wiring by the electrician €250 plus annual extra basic fees of about €120)

How did you decide on this?

Thanks everyone!
Satellite view of a building complex with map overlay and blue location marker.
Nida35a12 Sep 2024 12:01
Is the south side with the 10 kWp already fully utilized? For the household, heat pump, and car, that is only sufficient in summer; in spring and autumn, there is not much left for the car. From March until now, we have only drawn 22 kWh from the grid.
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Pete1909
17 Sep 2024 20:42
Unfortunately, my house is not yet available on the map of the suggested calculator (as of 2022).

I will use a meter :-)

But I have another question:

Instead of 22 modules, I could now go for 24 modules with each 455 for the heat pump. (then about 11 kWp)

Considering the orientation of the house, as shown in the picture above -> Does it make sense to install, for example, 3 rows of 6 modules on the "south side" and 2 rows of 3 modules on the back side?
As of 3 pm, we already had full sun on the other side until the evening today.

Or is it better to install the modules fully on the side that receives full irradiation between 8/9 am and 3 pm?

I am still undecided on this.

As of now, no additional modules will be added.
Pete1909 schrieb:

Hello everyone!
The photovoltaic topic has now caught up with me as well.
I ordered 22 modules (10 kWp) including a storage system (10 kW).

1) I would like to ask for an assessment of whether it would make sense to install modules on the back side of the house due to the roof orientation (see photo for the orientation).

The sun only reaches there in the afternoon; the planned roof area receives a lot from the south, so the battery/storage will be well charged. Does it even make sense to capture the evening sun? I don't yet understand the added value and whether the yield justifies the effort. Especially since direct irradiation on the side only occurs from the afternoon until evening.

Our consumption is as follows:
Air-source heat pump (water + heating): 3,300
Household: 2,600

An electric vehicle will likely be considered in the future.

2) Currently, we still have two meters (heat pump electricity at 22.67 cents / €8.15 monthly fee / household electricity at 30.49 cents / €13.84 monthly fee).
Does it still make sense to operate with two meters given our consumption? (Additional cost for cascading circuit by electrician €250 + additional annual monthly fees of about €120)

How did you decide on this?

Thank you all!
Nida35a30 Sep 2024 10:22
Pete1909 schrieb:

From 3 p.m. onward, we had full sun on the other side today, lasting until the evening.
In winter, this reduces to around 3–4 p.m., so it’s not really worthwhile.
The yield today and on Saturday with the sauna (yellow = photovoltaic, black = consumption, green = storage)
Mobile app view: Today's chart with generation, consumption, and battery state of charge, total values.

Energy chart September 28, 2024: green = consumption, yellow = generation, grid & battery.
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Pete1909
30 Sep 2024 10:35
We will install everything on the front side. With a roof pitch of 38 degrees, the rear side of the roof would only achieve about 65% efficiency compared to nearly 96% on the front. Your comment further supports this. Thanks!
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Evolith
2 Oct 2024 09:19
A cascade control setup makes sense when there is a significant difference in electricity prices. I believe I read somewhere that about 10 cents is the threshold. The basic fee also plays an important role.

We have a cascade control system. We pay 17 cents for the heat pump and 27 cents for household electricity. This makes it worthwhile because the additional consumption in winter mainly comes from the heat pump. Our photovoltaic system then only supplies the standby power for the house. In our case, the system is cascaded so that the household electricity demand is met first, and the heat pump is supplied afterward.

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