Before comparing solar quotes, send each installer your electricity usage. How much power you use during the day affects the savings, and a holiday home left empty for months needs a different calculation from one lived in all year. Ask what assumptions sit behind the payback estimate so you can judge whether it fits your home.
Start with your own bills
Gather a representative year of consumption if you can. Think about when the home uses electricity: pool pump, hot water, cooling, cooking or EV charging. A home that's empty for months is a different case from one occupied every day.
Ask how much generation the design expects you to use directly and how exported energy is valued. A calculation that prices every generated unit as a retail saving can make the return look better than the proposed arrangement warrants.
Check the roof before counting panels
The survey should consider shade, orientation, condition, fixings, waterproofing, cable routes, inverter location and future access. If the roof needs work, find out before installing equipment you may have to remove.
In an apartment building, establish roof rights and the community decision route. Having enough sunny space doesn't mean one owner can simply use it.
Compare the equipment and design
Ask for panel and inverter models, mounting, protections, monitoring, warranties and exclusions. Compare the expected production and how it was calculated alongside the installation price. This gives you a better basis for choosing than panel count or a savings total alone.
Include the administrative work
The agreement should identify who handles municipal, electrical, distributor and compensation procedures where applicable. IDAE describes the technical design and permissions as part of the project. Ask which final documents you'll receive and when, so you can follow up on anything still outstanding after installation.
Before you go ahead
- Consumption profile analysed
- Roof rights and condition checked
- Shading and cable route surveyed
- Production assumptions compared
- Administrative handover itemised
Common questions
Do more panels always mean a better return?
No. Value depends on usable generation, your consumption timing, export treatment, equipment and cost. Compare a design against real bills.
Can one apartment install panels for itself?
Possible arrangements exist, but using common roof space requires the proper owners' community process and a technically and legally suitable configuration.
Sources and further reading
Official information checked on 12 October 2026. Rules and procedures can change; verify the live source for your exact circumstances.