Photovoltaic system - rough cost estimate

Hello,

my question is quite vague in terms of timing and there probably isn’t an exact answer to it. I have a mid-terrace house that is now 28 years old. One roof surface is south-facing and I think that is suitable for a photovoltaic system. By chance, I saw an offer at a Swedish furniture store for a photovoltaic system (4 kWp) including storage and installation for 12,000 and some change. I always thought something like that would be much more expensive. Our current electricity consumption is 2800 kWh/a and at some point the old gas heating system will definitely have to be replaced. Possibly with a heat pump. Now I wonder. Is the price realistic for a photovoltaic system with everything included? Surely you need scaffolding or do they do it through the roof window with straps?

Without knowing which components are installed and what the exact on-site conditions are, I would call 12k for 4kWp exorbitant. If you hadn’t mentioned a Swedish furniture store, I would have guessed en*al as the provider. For a small system, I would set 2k per kWp as the upper limit. 3k per kWp is beyond outrageous. We paid 25k for 12kWp spread over three roof sides with high-quality components, 11kWh storage, and 65 metal roof tiles (each piece alone costs 30€). That means just over 2k per kWp. Leaving out the storage and special extras, we would have landed at 1.4k per kWp. The system was commissioned in February 2024.

Purchased in December 2023. 11 kWp with 10 kWh Huawei storage and inverter. Go-e Charger, Controller and Wallbox. Complete for 19k. BaWü. I think it is currently possible to get it slightly cheaper.

Ok, thank you very much for your assessment. As I said, I still have very little knowledge about the topic. How large should the system be? Is there an estimate? We consume about 2700 kwh/a. Maybe at some point a heat pump could replace the current gas heating. We do not have an electric car, and I don’t see that for us at the moment either. In other words, I don’t need a wall box, or it could still be retrofitted at some point.

The size of the system I would personally always depend on several factors, and the biggest one is the payback period.
Whereas the economic efficiency is really a balancing act. Nothing must break for many years, many also like to ignore the operating costs of the system.
By now I have come to say about our own system that we only have it because 1) we could afford it, 2) we received a small subsidy, and 3) thanks to the heat pump and recently the electric car, I can maximize self-consumption and to some extent am not exposed to price fluctuations in the market.
On the other hand, there are insurance costs (partially included in the residential building), risk of component failure. Even if this happens within the warranty period, the solar power will probably be gone for many weeks/months until replacement parts arrive or the claim is recognized at all. And last but not least, the increased effort for a repair on the roof should there ever be something.
I would do it again personally, but I can well understand if someone thinks this is a simplistic calculation. In most cases, it probably will be so at first.

The size of the photovoltaic system should only be limited by the space on the roof.