July 16, 2026 · 5 min de lectura
Solar panels for the building: majorities, steps and what to check
More and more buildings are considering solar panels. The legal side is simpler than people assume; deciding it well, less so.
The majority
Installing systems that harness renewable energy on common elements enjoys a favoured regime under Spanish horizontal property law: unanimity is not required. The law deliberately lowers the majority needed precisely so this kind of installation does not get blocked.
It is worth confirming the exact majority applicable to your case before the meeting, because it depends on how the installation is framed and on whether costs are passed on to those who did not want it.
The steps, in order
- Preliminary study: available roof space, orientation, shading, condition of the roof. If the roof needs repair, do that first — taking panels down to fix the roof is money thrown away.
- Decide the model: self-consumption for shared services (lift, entrance, car park) or collective self-consumption shared among the flats. They are not the same in cost or in administration.
- Three comparable quotes, with estimated output, guarantees and maintenance.
- A resolution at the meeting, covering amount, cost allocation and financing.
- Paperwork: permits, legalising the installation and applying for whatever reliefs are available.
What to ask before signing
- What output they estimate and on what assumptions. Be wary of estimates with no shading or losses factored in.
- What guarantees cover the panels, the inverter and the installation — usually three different periods.
- Who maintains the installation and at what annual cost.
- What happens with the roof: who answers if a leak appears where something was fixed.
- How output is shared between flats and shared services, and how that split gets revised if somebody joins later.
The point most often overlooked
Local tax reliefs (council tax, permits) and available grants vary enormously by municipality and by funding round. Check before deciding, because it can shift the payback period considerably — and with it, the decision.
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