UPAC in practice
Your system feeds your own consumption first. Whatever you do not use can go to the grid and, if you sign a contract with a retailer, be sold. ERSE lists it as the owner's duty to size the system so that production comes as close as possible to consumption.
The reason is price. On a fixed price contract the surplus averaged about €0.05 per kWh in 2026, according to Portal Energia; indexed contracts follow the hourly OMIE market price minus a management fee. Every kWh you use yourself saves the full price per kWh on your bill, which is several times more.
UPAC and UPP side by side
| UPAC | UPP | |
|---|---|---|
| What it is for | Self consumption, surplus optional | Selling all production to the grid |
| Who it suits today | Homes and businesses using their own power | Older contracts; not how new home systems are set up |
| Law | Decreto‑Lei 15/2022 | Decreto‑Lei 153/2014, then 162/2019 |
| Registration | Prior notice on the DGEG portal for 700 W to 30 kW | As set in the original contract |
If the house already has panels
Ask the seller for the DGEG registration and the grid contract. The documents say whether the system is a UPAC or an older UPP, microprodução or miniprodução unit, and on what terms. The DGEG registration has to move to the new owner, which the account holder on the DGEG portal can do.
Tax on the surplus
Income from selling the surplus of a UPAC up to 1 MW is outside IRS up to €1,000 a year (CIRS article 12). Above that it is taxed. Most homes sell far less.
- Can I still sell all my production at a fixed tariff?
- Not as a home system set up today. New home systems register for self consumption and sell only the surplus, at market related prices.
- Do I have to sell my surplus?
- No. Selling needs a contract with a retailer. Without one, size the system to use what it produces.
- What is collective self consumption?
- Several consumers sharing one or more production units, for example in a building. ERSE counted 331 sharing agreements involving 1,352 consumers at the end of 2024.
Sources
- ERSE, self consumption FAQ (FAQ do regime de autoconsumo), May 2025 (UPAC sizing duty, surplus, collective self consumption)
- ADENE and DGEG, practical guide to self consumption, chapter I (Decreto‑Lei 15/2022 scope)
- Decreto‑Lei n.º 162/2019, Diário da República (UPAC and UPP regime before 2022)
- Portal das Finanças, CIRS article 12 (surplus sale income up to €1,000)
- Portal Energia, the surplus regime in 2026, 21 September 2026
- ERSE, self consumption report for 2024, published 10 September 2025