ᐅ Photovoltaic Consultation: 45° Hipped Roof Facing North/South

Created on: 17 Apr 2025 15:06

Hello everyone,

I am new to photovoltaics and have a few general questions: The building is oriented north/south and has a hip roof with a 45° pitch. I used PVGIS and got about 540 kWh/kW peak for the north side and 1180 kWh/kW peak for the south side.
Is it common to fully cover the north side under these conditions? Does it provide any base load during winter? I suppose this also depends on the additional costs of installing panels on the north side. I am currently looking for companies and will share the prices here.
With current prices, a battery seems to make sense. Is there a magic price threshold in €/kWh and guidance on how large to size the battery?

Thank you for your help.

hanghaus202322 Apr 2025 14:12

#25

@kbt09 This is the invoice for my house as an example.

kbt0922 Apr 2025 14:22

#26

When was that? Your estimated costs seem very high to me, considering the threads I’ve seen in a specialized forum.

EDIT:
Additionally, I always wonder with these return-on-investment calculations when a regular gas heating system and electricity supply without solar panels actually pay off *smile*

hanghaus202322 Apr 2025 15:10

#27

The house has 240 m2 (2,583 sq ft), including an 80 m2 (861 sq ft) granny flat, and is occupied by 6 adults (3 generations). Built in 2002, it is not up to current energy efficiency standards.

An alternative with gas was not an option.

nordanney22 Apr 2025 15:21

#28

The yield from the north side doesn’t matter at all. Install the system at full capacity. The fixed costs make installing only on the south side much more expensive compared to covering the entire roof.

Current example (all including offers) for a system in Stuttgart from 10.04:
7.2 kWp south-facing + 10.2 kWh LFP battery: €15,999 (≈ $2,222/kWp including storage)
13.95 kWp south-/north-facing + same battery: €19,499 (≈ $1,398/kWp including storage)

I wouldn’t even consider how much energy the north side produces. With the additional cost of €3,500 for 6.75 kWp (≈ $518/kWp), the upgrade is always worthwhile.

wiltshire24 Apr 2025 11:10

#29

nordanney schrieb:

I wouldn’t even begin to consider how much yield you get in the north. With the additional cost of €3,500 for 6.75 kWp (= €518/kWp), the upgrade always pays off.

I see it differently because the yield is what your system actually produces. The kWp value only describes the technically possible peak power of the panels. Assuming a price advantage of solar electricity compared to grid electricity of €0.20/kWh, you would first need to generate 17,500 kWh more solar energy and use it entirely yourself to justify the €3,500 investment. This might pay off in a household with a pool heating system. With a typical consumption profile, I don’t see an attractive return on investment here.

nordanney24 Apr 2025 11:29

#30

wiltshire schrieb:

I see it differently because the yield is what your system actually produces. The kWp only describes the technically possible peak power of the modules. Assuming a cost advantage of solar electricity compared to purchased electricity of 20¢/kWh, you would first need to generate 17,500 kWh more solar yield and use it entirely yourself to justify €3,500. This might be worthwhile in a household with a pool heating system. With a typical consumption profile, I don’t see an attractive return on investment here.

With a pure north-facing orientation in Saarland, that's about 3,700 kWh per year (p.a.) that can be gained additionally (if this applies to the original poster). Now you can calculate for yourself what the possible yield is and whether it’s worth feeding in and/or self-consuming 74,000 kWh over 20 years (heat pump, car, etc.).
Especially in the mornings and evenings with east/west sun exposure, it already makes sense (a storage system is available anyway).

ᐅ Photovoltaic Consultation: 45° Hipped Roof Facing North/South

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