Understanding the Different Types of Solar Systems
As solar becomes mainstream in Portugal, it’s critical for homeowners to understand which type of system fits best — especially under evolving regulations. Below is an up-to-date guide (as of mid-2025) to the main solar system types, what Portuguese law requires, and pros/cons from a local perspective.
1. Grid-Tied (On-Grid / Self-Consumption with Export)
A grid-tied or self-consumption (autoconsumo) system for Portugal is normally connected to the public grid. You use the solar energy you produce, and if there is surplus, you can export (sell) it back to the grid (depending on your registration, capacity, and contract).
Under Decree-Law 162/2019 and related self-consumption regulation (published in 2020), the accounting of production vs consumption is done in 15-minute periods. That is, electricity generated and consumed is compared in these intervals for offsets.
Portuguese law also classifies systems by size with different registration or notification requirements:
- ≤ 700 W → no registration required pearlsofportugal.com+1
- 700 W up to 30 kW → prior notification (via SERUP / DGEG)
- 30 kW up to 1 MW → registration + operating certificate required
- 1 MW → full licensing regime, capacity allocation etc.
What to Consider
| Factor | Advantage | Challenge |
| Self-consumption accounting in 15-min intervals | Better alignment: you can offset your own consumption more precisely. | Surplus exported beyond what is consumed in that same 15 min may not be fully credited. |
| Export price / compensation | You get some value for surplus energy (often €0.04–€0.08/kWh, depending on contract) | Export price is typically much lower than your retail electricity price, so selling back is rarely as profitable as self-use. |
| Registration, permissions & bureaucracy | For small systems (<700Wp), the process is simplified (notification regime) | Larger systems (700Wp to 30kWp) require full registration and certificates. |
| Grid dependence & outages | You are still connected to grid: when solar is insufficient, you draw from it | In standard systems, during a blackout the inverter shuts off (for safety) unless you have hybrid / backup arrangement |
| Financial return | Often shortest payback thanks to grid backup, known tariffs, and reduced electricity bill | The margin on exported energy is low; ROI depends heavily on self-consumption rate and export compensation |
| VAT & tax regime (Portugal specific) | Up until 30 June 2025, solar installations benefit from 6 % VAT (for residential / qualifying cases) | From 1 July 2025 onward, that 6 % reduced VAT rate ends; new installations will incur standard 23 % VAT unless legislation extends or modifies the regime. |
Sample Portuguese Scenario (Illustrative)
Suppose a homeowner installs a 5 kW system. During mid-day, their consumption is 3 kW and generation is 4 kW — so 1 kW is surplus. In that same 15-minute block, they may offset their own consumption fully but the 1 kW extra is exported. That exported energy is remunerated at a lower price. The key is maximize self-consumption, use loads when solar is available, or add batteries or loads to absorb it.
2. Hybrid Solar Systems (Grid + Battery + Export Capability)
A hybrid system is essentially a self-consumption / grid-tied system but with battery storage added. You can store surplus solar energy for later use (night, low sun periods, or even during outages) and still stay connected to the grid as backup.
Technically, such systems must comply with the same UPAC registration/notification rules depending on their installed power. The battery makes management more complex (inverter needs to mediate solar, battery and grid). The system must also follow the 15-minute accounting rules for production vs consumption.
What to Consider
| Feature | Pro | Challenge |
| Higher self-consumption | You can capture surplus energy that otherwise would be exported cheaply and use it later, increasing your effective return | Batteries add significant capex; the cost and lifecycle of batteries must be factored |
| Backup capability | In outages, you may maintain power (if the hybrid inverter and system are designed for islanding) | Requires more complex design, safety, maintenance, and protection schemes |
| Return on investment | Because the battery increases self-consumption, you reduce reliance on grid imports and increase savings | Battery degradation, replacement cost, and efficiency losses reduce net benefit over time |
3. Off-Grid / Stand-Alone Systems (No Grid Connection)
What it Is (in Portugal contexts)
An off-grid system is fully independent of the public electricity network — it relies entirely on solar generation, battery storage, and often a backup generator. These are rare in urban Portugal unless in remote locations or for specific setups (e.g. Remote cabins, agricultural sites off the grid). Because they have no grid connection, they are outside many of the UPAC / self-consumption frameworks.
What to Consider
| Feature | Advantage | Challenge |
| Complete energy autonomy | No electricity bill, no dependence on grid or grid tariffs | Very high cost: you must oversize panels and batteries to ensure reliability |
| Design complexity | You must design for worst conditions (long cloudy periods) and include backup generator | Maintenance burden is higher; battery replacement is critical |
| No VAT/export complexity | You may avoid grid export regulatory complexity, but parts will still be subject to VAT | In Portugal, remote areas tend to be rare; grid expansion is extensive; reselling surplus is impossible |
| No support from grid or compensation | Full independence | Lack of grid safety, no fallback, possibly limited reliability |
Unless your property is truly off-grid (no chance of grid access), most Portuguese residential/commercial projects will lean toward self-consumption + export or hybrid.
Specific Portuguese Additions & Latest Changes (Mid-2025)
Feed-in / export compensation
Portugal no longer generally offers generous fixed feed-in tariffs for new small projects. Instead, export / export rights are handled via market or negotiated compensation.
The compensation for exported energy tends to be in the range of €0.04 to €0.08 per kWh (depending on contract and conditions) — considerably lower than retail electricity prices.
Because of that disparity, maximizing self-consumption is more financially favorable than exporting large volumes.
Simplified registration / licensing thresholdsThe Portuguese regulatory regime under Decreto-Lei n.º 15/2022 streamlines licensing for small PV systems, including minimal requirements for small UPACs.
For example, small installations (≤ 700 W) require no registration; those up to 30 kW require simple notification; above that, more formal registration and certificates are needed.
Grid conditions, capacity & connection
Exporting excess generation often requires having grid capacity rights allocated and approval from the grid operator (E-REDES in Portugal).
Lexology
Metering must be bidirectional / smart / adapted to capture flows both in and out.
Grid constraints or delays in connecting new capacity are real risks (in some regions grid reinforcement is needed).
Self-consumption / 15-minute rule
The rule that generated energy is accounted in 15-minute intervals means that only the portion of generation that coincides with consumption in that same 15-minute slot is fully offset. Surplus beyond that is treated as export.
This rule pushes toward scheduling loads (e.g. EV charging, washing machines) when solar is active to maximize offset.
No net-metering in classic sense
Portugal’s self-consumption regime is not classic “net-metering” (i.e. unlimited aggregation over time). Energy export is only credited up to the simultaneous consumption in each 15-minute block, reducing “banking” of exports across long time intervals.
Regulatory and legal framework
The main legal basis is Decree-Law 15/2022 (14 January) which updates and consolidates the legal framework for renewable energy and self-consumption.
The older Decree-Law 162/2019 established many of the rules for self-consumption and accounting.