Putting solar panels on a roof is roof work. If the roof is old, badly sealed or made of asbestos-cement, panels can bring a new problem. This guide gathers what to check before you sign: the roof, the energy law, the town hall, the building association, VAT and aid. We do not recommend firms.
Updated on 3 November 2026. General information, not legal or tax advice.
The essentials
- The roof comes first. A technical guide from APICER says it matters to assess the roof’s watertightness and its supporting structure when fitting panels.
- Asbestos-cement: do not drill. Drilling material that contains asbestos greatly increases the risk of releasing fibres (DGS).
- Up to 30 kW, a prior communication to the DGEG is enough. Up to 800 W, without feeding surplus into the grid, not even that (Decreto-Lei n.º 130/2026).
- VAT is 23%. The 6% rate for panels ended on 30 June 2025 and has not been restored.
- Aid: on 3 November 2026, the Fundo Ambiental had no notice open for applications.
The roof comes first
Condition and age. Panels cover the tiles. A repair underneath means taking them down. If the roof already leaks or is near the end of its life, fix that first (our conclusion). See repair or replace and the causes of leaks.
Fixings and leaks. The APICER guide (2018) says that fixing equipment and passing pipes through the roof are points of great vulnerability that call for a qualified technical approach. Done badly, they fail in the short or medium term. Ask how each fixing is sealed and who answers if the roof leaks (works warranty).
Structure. We found no official Portuguese guide on the weight a house roof can carry. The APICER guide only asks that the supporting structure’s performance be assessed. Ask who checked it, with what data, and get that in writing.
Repairs later. Ask the contract to give the price of taking the panels down and putting them back. Going onto the roof is a fall risk: see work at height.
An asbestos-cement roof
The DGS says asbestos in good condition, which does not crumble by hand, is as a rule low risk. Cutting, drilling or breaking it substantially increases the risk. Only a laboratory test confirms whether asbestos is present. Fixing panel frames to asbestos-cement sheets means drilling them. We found no official Portuguese rule on panels over such sheets. See the asbestos guide and the removal law.
Shade and orientation
We read no official source with ideal angles, so we give none. The European Commission has a free tool, PVGIS, that estimates output for a slope and orientation of your choice and accepts a horizon file. Ask the installer for a simulation with your data and check it.
What the energy law asks
Text of Decreto-Lei n.º 15/2022 as amended by Decreto-Lei n.º 130/2026 (in force since 28 August 2026; it applies only to procedures started afterwards):
| Size of the unit (UPAC) | Procedure |
|---|---|
| Up to 800 W, no surplus fed into the grid | Exempt from prior control (previously 700 W) |
| Above 800 W and up to 30 kW | Prior communication; the receipt authorises installation |
| Above 30 kW and up to 1 MW | Prior registration and operating certificate (2022 text) |
Above 800 W, installation must be done by a registered electrical installation firm or a responsible technician (article 84). Ask for the receipt of the prior communication before the work.
Town hall, listed buildings and municipal plan
Since 1 October 2026, the RJUE treats as a work of minor urban relevance (exempt from licence and prior communication) photovoltaic panels tied to the main building that do not exceed the roof area or its height by 1 m. It includes batteries and solar thermal collectors if the tank is hidden (article 6-A, no. 1, point g). Article 48 of Decreto-Lei n.º 15/2022 says projects up to 1 MW are not subject to prior control under the RJUE. But:
- The exemption does not set aside territorial plans, heritage rules and technical standards.
- The RJUE excludes listed buildings or buildings being listed, those in a protection zone and those in listed ensembles or sites (article 6-A, no. 2). Ask the town hall first.
- The developer informs the town hall up to five days before starting, even for exempt works (article 80-A). See the works permit guide.
If you live in a block
The roof is a common part, as the guide to the roof in a condominium explains. In the original 2022 text (article 85), whoever wants to fit panels on a common part not for their exclusive use informs the administration 60 days ahead. The administration has 20 days to object, for example if it harms the building’s architectural line or safety. There is an appeal to the owners’ assembly, called within 30 days at most. With no reply, the communication serves as title to occupy the common part.
Insurance
We found no official rule. Tell the insurer in writing, check whether the panels are in the insured sum and read the exclusions (our advice). See home insurance.
VAT: the 6% has ended
Item 2.37 of List I of the VAT Code (solar panels) was created by Lei n.º 12/2022, and the law says it ceases on 30 June 2025 (article 330, no. 3). A binding ruling of the tax authority (AT) of 16 October 2025 calls it «cessada» (ended). The 2026 State Budget (Lei n.º 73-A/2025) does not restore it: it does not appear in the VAT changes. On 26 May 2026, Parliament only recommended that the Government propose restoring it (Resolution n.º 132/2026). A recommendation is not law. Many texts still say 6%: they are out of date. See the guide to VAT on works.
Aid
The Fundo Ambiental’s «Apoios 2026» page says no form is open, and the notices for energy efficiency in buildings are closed. Vale Eficiência II closed beneficiary applications on 31 October 2024. On 30 October 2026, the Fund told already-eligible beneficiaries who were waiting for a technical facilitator about a simplified mechanism, with expressions of interest from 23 November. It serves only them. See the insulation aid.
What we could not confirm
- Weight, orientation and service life of panels: no official source or dated data sheet.
- Whether article 85 has changed since 2022. We read the original text.
- How the RJUE and article 48 combine for listed buildings.
- Whether the labour for panels on a roof being renovated can carry 6% VAT under item 2.27. We found no binding ruling.
- Laws after 26 May 2026 on VAT. We found none.
- A solar «voucher» cited by commercial guides: we saw no official notice.
- Insurance rules for panels.
Sources (read on 3 November 2026)
All in Portuguese.
- Decreto-Lei n.º 130/2026, 29 June (articles 9, 11, 48, 84). DGEG, note on the decree (28 August).
- Decreto-Lei n.º 15/2022, original text (articles 11, 84, 85).
- Decreto-Lei n.º 108/2026, copy of the Diário da República (articles 6, 6-A, 80-A); Decreto-Lei n.º 155-B/2026 (in force from 1 October).
- Lei n.º 12/2022 (articles 288 and 330); Lei n.º 73-A/2025 (articles 75 to 77); AT, binding ruling 28690; Parliament Resolution n.º 132/2026.
- APICER, Guia para Projeto e Aplicação de Telhas Cerâmicas, 2018.
- DGS, Amianto.
- European Commission (JRC), PVGIS, updated 10 October 2025.
- Fundo Ambiental, Apoios 2026, open and closed notices and Vale Eficiência II.