ᐅ Baden-Württemberg Photovoltaic Requirement for Existing Buildings – Replacing Roof Tiles

Hello dear forum,

maybe some of you have faced the same situation or have the same question.
I couldn’t find anything clear on the internet regarding this.

Here is the initial situation:

- Solid brick house built in 1970
- Heating system with storage heaters running on 100% green electricity tariff, plus a tiled stove
- Roof insulated with insulation between rafters, attic insulated with XPS boards, plastic double-glazed windows,
so definitely not a modern insulation standard
- Annual energy consumption – daytime electricity (peak) 2,500 kWh (2,500 kWh) – nighttime electricity (off-peak) 7,400 kWh (7,400 kWh)
- Most of the living areas are heated with the tiled stove

In the coming years, the roof tiles will need to be replaced. From what I understand, in Baden-Württemberg, I would then have to install a photovoltaic system.
This raises the following questions for me:

- How am I supposed to finance this with the current high interest rates? The monthly cost, including the mortgage, would simply be too high.
- We can’t afford a complete renovation (insulation, new windows, heat pump, etc.).
- As far as I know, you can’t power storage heaters with a photovoltaic system, even with a battery storage, because they consume too much electricity. Plus, in winter, when we need the most electricity, too little electricity is generated...
- So, at most, a small photovoltaic system would make sense to cover our daytime consumption (about 2,500 kWh (2,500 kWh) per year).
- I have concluded that such a system is not yet economically viable for us, especially with the high purchase costs and high interest rates. Is it possible to avoid the photovoltaic installation requirement if you don’t have the financial means and only need to replace your roof tiles?

Has anyone been in a similar situation? What approach did you take or what are your plans?

Thank you very much!

You can’t avoid them, but you can look for a good offer. Then it will pay off reasonably well through the feed-in tariff. A larger system is usually more cost-effective than just meeting the minimum requirement.

bloodyscorpion schrieb:

- How am I supposed to finance this with the current high interest rates? The monthly burden including the mortgage would simply be too high.

That’s why you consider in advance which measures will be necessary in the coming years and adjust your offer accordingly. There’s no point in complaining afterward; if you bought recently, the photovoltaic obligation was already known.

Do you have an electricity tariff that offers cheaper rates at night for charging storage heaters? If not, and you pay regular (or nearly regular) electricity prices for charging the storage heaters, it might be worth considering charging them during the daytime when your solar power is available. Admittedly, this won’t be enough in winter, but especially during the transitional seasons, I can imagine you could make excellent use of solar electricity and significantly increase your self-consumption compared to average, which could considerably reduce your electricity costs. This is why a photovoltaic system might pay off much faster than is often expected. Of course, this depends a lot on your specific setup and electricity tariffs. But the idea that storage heaters can’t be powered by solar because they draw too much electricity sounds very strange to me. (That you might not be able to fully charge them is one thing, but it should still help, right?)

Regarding financial aspects, I believe there are some loan options available through KfW and L-Bank for photovoltaic systems, but it’s true that these are currently not particularly low-interest. Depending on how much time you have left (you mentioned “in the next few years”), I would start saving now to possibly avoid needing too much credit. Some things may even become a bit cheaper if you combine the installation with a roof tile replacement. For example, you might already have scaffolding in place and could consider using carrier tiles (roof tiles that integrate the support structure for the photovoltaic system) instead of removing and cutting existing tiles. (I’m not sure if this really turns out cheaper or not.) Alternatively, you can probably save a lot on photovoltaic costs if you feel confident enough to handle the installation yourself and only pay someone for the electrical connection (but this wouldn’t be an option for me). However, with many subsidized loans, professional installation is often mandatory, so self-installation might not be allowed.

Hello everyone,

Thanks for the initial responses.
When we bought the house, there was no mention of a photovoltaic system being mandatory.
Anyone who has purchased a house in the greater Stuttgart area in recent years knows what price levels we are talking about here.
There are still some financial reserves, but I don’t want to invest in a project that probably will never really pay off or become cost-effective.

That’s correct, we currently have an off-peak electricity heating tariff NT (about 19 cents) and peak daytime HT (28 cents) with 100% green electricity.
So, in theory, we are heating 100% renewably.

I need to have some offers prepared by local solar providers, including financing options (L-Bank, KFW, etc.),
and create a cost-benefit analysis. At least the daytime consumption and the three hot water tanks could be supplied by the photovoltaic system.
Yes, I have an acquaintance who is a roofer; maybe it could also be done privately…

Does anyone here have experience with infrared or electric underfloor heating? Are they more efficient than night storage heaters?

Best regards

bloodyscorpion schrieb:

Does anyone here have a similar initial situation, and how did you proceed or what are your plans?

No personal experience. But there are exceptions in Baden-Württemberg, including undue hardship – a rejected loan application can be one of those reasons. Your bank will surely assist you with the loan denial. If you already say you can’t afford it, the bank probably won’t say otherwise.

bloodyscorpion schrieb:

There are still financial reserves, but I won’t invest in a project that probably will never really pay off or amortize.

That’s a misconception. There are practically no situations where a photovoltaic system doesn’t pay off. With as much self-consumption as possible, payback periods under 10 years are very achievable.
Take, for example, a 10 kWp system that produces 10,000 kWh annually. You install it on your roof for about €13,000 (just an example, photovoltaics have become quite affordable recently).
With full feed-in and no self-consumption, the system pays itself off after 16 years—not amazing, but after that, you still gain returns from a paid-off system.
With 20% self-consumption, you save external electricity costs of 30 cents/kWh. So you save about €600 annually on electricity and feed in for €648. The system then pays off in just over 10 years. If electricity prices rise, the payback period is below 10 years. With higher self-consumption, it is under 10 years.
A photovoltaic system is the only investment in a house that actually pays off financially (in my example, a €13,000 investment yields about €25,000 over 20 years). An ETF might be better, but please don’t say a photovoltaic system doesn’t pay off at all.

bloodyscorpion schrieb:

Does anyone have experience with infrared or electric surface heating systems? Are they more efficient than storage heaters?

I don’t have specific experience, but I looked into it briefly. Storage heaters can apparently convert only about 30-40% of the electrical energy into heat. With electric direct heating systems (which include infrared and electric surface heaters), efficiency is almost 100%. Heat pumps are even more efficient because they extract some of their energy from the surrounding environment.

If a complete switch to water-based radiators, underfloor heating, or wall heating is not an option, air-to-air heat pumps might still be an alternative (see reservations in the next paragraph). These are basically modern air conditioning units (as split systems with an outdoor unit; it’s called “multi-split” when multiple indoor units are connected to a single outdoor unit) that can also provide heating. Their efficiency drops at subzero outdoor temperatures, but at positive temperatures they can achieve over 200% efficiency (don’t quote me exactly on that) and are therefore particularly efficient during transitional seasons. (For exact performance in deep winter, you’d need to check further, but I suspect they can still outperform direct electric heaters.) In any case, it’s best to research all of this yourself as well.

I can’t say how well these systems work in poorly insulated houses. I imagine it could become uncomfortable if the heat pump has to blow very warm air because too much heat is lost to the outside. They tend to work better in well-insulated buildings.