ᐅ Photovoltaic Consultation: 45° Hipped Roof Facing North/South
Created on: 17 Apr 2025 15:06
C
CC35BS38
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.
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.
W
wiltshire20 Apr 2025 16:18Nida35a schrieb:
With a 45° roof pitch, only the south side seems worthwhile,
east and west are too small and triangular, When planning photovoltaics, it makes sense not only to focus on annual consumption but also to consider typical consumption patterns. If you have electricity demand in the morning and evening, the small east-west surfaces can help reduce the required battery capacity by a few kilowatt-hours through sensible sizing. These calculations vary greatly on an individual basis.
Don’t forget: each orientation needs its own MPPT, and the south roof may need two to stay within the performance range. That means extra cost.
hanghaus2023 schrieb:
Does your home connection support two electric vehicle charging stations? Usually, one charging station is sufficient for multiple electric vehicles. I haven’t come across a household where two chargers installed on the house made sense, even though I know several people with two or more electric cars.
Nida35a schrieb:
Are solar roof tiles not an option for east and west? While I’m a big fan of solar roof tiles and even have them on my own house, economically it wouldn’t make sense because solar tiles need to fit into the existing system—and that definitely isn’t the case here.
A friend of mine installed shingles in an overlay mounting system. They have dimensions roughly equal to one tile height and 4–5 tile widths. That helps to better utilize the triangular area and looks quite nice. The shingles came from Eckpack in Darmstadt.
Thank you for the ideas and advice. A garage with a flat roof (south or west-facing possible) is still an option. I will discuss this with the companies, as well as the east-west layout. Ideally, the roof would not be used to maximize the area, but since this concerns a used property, it was not within our control. I would prefer to avoid major changes to the roof.
M
MachsSelbst21 Apr 2025 23:05It depends when it comes to the garage. Will it be shaded from one or more directions? If not, it’s best to install the system flat, not raised. And if you can/are allowed to... do it yourself there.
Solar panels are generally not worthwhile mainly because professional companies charge ridiculous prices. A few modules and an inverter don’t cost much. It only gets expensive when the specialist company performs their “voodoo.”
On the house roof... only cover the south-facing side fully; north is a waste of resources and money.
Because:
13.2 kWp with a 9.6 kWh battery storage currently costs around 20,000 EUR.
With this, you save about 4,000 kWh per year, which you would otherwise need to buy, equaling nearly 1,400 EUR per year (based on current prices from my utility). That means it takes about 15 years before you’ve saved your first cent compared to just buying from the grid...
Now consider if you also spent a lot of money fully covering the north side, which would produce much less yield.
Solar panels are generally not worthwhile mainly because professional companies charge ridiculous prices. A few modules and an inverter don’t cost much. It only gets expensive when the specialist company performs their “voodoo.”
On the house roof... only cover the south-facing side fully; north is a waste of resources and money.
Because:
13.2 kWp with a 9.6 kWh battery storage currently costs around 20,000 EUR.
With this, you save about 4,000 kWh per year, which you would otherwise need to buy, equaling nearly 1,400 EUR per year (based on current prices from my utility). That means it takes about 15 years before you’ve saved your first cent compared to just buying from the grid...
Now consider if you also spent a lot of money fully covering the north side, which would produce much less yield.
M
MachsSelbst21 Apr 2025 23:28Yes, before anyone complains: the remaining 8,000 kWh are of course fed into the grid, generating an impressive 640 EUR per year. But we have only considered the pure investment costs for the photovoltaic system, excluding maintenance, cleaning, a smart meter, photovoltaic insurance against hail, and no interest on the loan for the purchase...
These factors tend to balance each other out well.
Even a fully paid photovoltaic system installed by a professional company in an optimal south-facing location with 100% self-consumption does not break even in less than 10 years...
These factors tend to balance each other out well.
Even a fully paid photovoltaic system installed by a professional company in an optimal south-facing location with 100% self-consumption does not break even in less than 10 years...
H
hanghaus202322 Apr 2025 12:22Here is my calculation. Without KfW funding, this is not profitable.
| Investment: | |||
| Heat pump | €32,000.00 | ||
| Photovoltaic system 17 kWp, 10 kW battery, 1 wall charger | €31,000.00 | ||
| KfW funding | - €17,000.00 | ||
| KfW funding | - €6,000.00 | ||
| €40,000.00 | |||
| Previous costs: | |||
| Gas | €2,000.00 | ||
| Electricity | €2,000.00 | ||
| Diesel | €1,900.00 | ||
| Total | €5,900.00 | ||
| New costs | |||
| Gas | - € | ||
| Electricity | €2,750.00 | ||
| Feed-in tariff | - €540.00 | ||
| Electric car, 20,000 km (12,500 miles) / year, charged only at home | included in electricity | ||
| Total | €2,210.00 | ||
| Cost savings per year | |||
| €40,000.00 | / | €3,690.00 | |
| Payback period | 10.8 | years |
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