Should Your Solar System Export Electricity to the Grid in Portugal?
If you install solar panels in Portugal, one of the small but important technical decisions is how your inverter is configured.
Your installer can set the system to either:
- Allow excess electricity to be exported to the grid, or
- Limit export (sometimes called “zero-export”), where your system only produces power for your home.
For many homeowners this setting is never explained, yet it can affect how much value you get from your solar system.
In this article we’ll explain how it works, the pros and cons of each option, and why the best setting often depends on the size of your battery.
First: How Solar Energy Flows in Your Home
A typical solar system works in this order:
- Solar panels produce electricity
- Your home uses the electricity first
- Your battery stores extra energy (if you have one)
- Any remaining electricity can go to the grid
If export is disabled, the inverter simply reduces production so that nothing flows into the grid.
Option 1: Export Surplus Solar Energy to the Grid
When export is enabled, any unused electricity is automatically sent to the national grid.
Pros
You can earn money from excess electricity
Homeowners in Portugal can sell surplus solar energy through an electricity trader.Typical export prices are around:
- €0.03 – €0.08 per kWh
While this is lower than the price you pay for electricity, it still adds value to the system.
You maximise your solar production
If your system produces more electricity than your home is using, exporting ensures that all the energy your panels generate is used somewhere.
Without export, that electricity is simply lost.
You may not need a large battery
Exporting energy means you don’t have to store every extra kWh in a battery.
This can reduce the need for expensive storage.
Better for larger solar systems
Homes with larger solar systems often produce significant midday surplus. Export ensures this energy is not wasted.
Environmental benefit
Your solar electricity helps power other homes through the grid.
Cons
Export prices are relatively low
Electricity you use in your home is far more valuable than electricity you export.
Typical example:
- Electricity you buy from the grid: €0.20 to €0.30 per kWh
- Electricity you sell: €0.03 to €0.08 per kWh
So using your own solar power is usually 4–5 times more valuable.
You must register with an electricity trader
To get paid for exports, you need to sign up with an energy buyer.
Your meter must measure exports
Most Portuguese homes already have a bi-directional smart meter, which can measure electricity flowing both ways.
Some additional administration
The process is simple, but there is some paperwork.
Option 2: Limit Export (Self-Consumption Only)
With export limitation enabled, your solar system will only produce electricity when your home can use it or store it.
If your house doesn’t need the power, the inverter simply reduces production.
Pros
Simple system setup
No need to register with an energy trader.
Focus on self-consumption
You use solar energy directly in your home, which is the most valuable use of electricity.
Sometimes required by grid operators
In certain locations the grid connection may require export limitation.
Cons
Some solar energy may be wasted
Imagine the following situation at midday:
Solar panels could produce 5 kW
Your home is only using 1.5 kW
With export limitation on:
The inverter reduces output to 1.5 kW
This means 3.5 kW of potential solar energy is lost.
Lower overall system efficiency
Your panels are capable of producing more electricity than they are allowed to.
Less benefit from larger systems
If your system is capable of producing more energy than your home uses, the extra production is simply curtailed.
Why Battery Size Changes the Answer
The best export setting often depends on how large your battery is.
Homes With Small Batteries (≈10kWh or less)
For most homes with small residential batteries, it usually makes sense to allow export.
Here’s why.
Small batteries fill up quickly - often by late morning on sunny days.
After the battery is full, your solar panels may still produce several hours of strong power.
If export limitation is on, that production is simply lost.
Allowing export means:
- Your home uses solar first
- Your battery charges
- Any extra electricity is exported to the grid
Even though export prices are lower, getting paid something is better than wasting energy.
Homes With Larger Batteries
For systems with larger battery storage, the situation changes.
Large batteries can store a much bigger share of the daily solar production.
This means most surplus energy can be kept and used later in the evening or overnight instead of being exported cheaply.
In these systems, keeping export limitation on can make sense because:
- Stored electricity replaces expensive grid electricity later
- Export prices are relatively low
- Maximising self-consumption becomes the best strategy
What Most Homes in Portugal Do
Most modern systems operate in this order:
- The home consumes solar electricity first
- The battery stores excess energy
- Any remaining electricity is exported to the grid
This approach typically produces the best financial outcome for homeowners.
One Important Detail
Even if you do not sign a contract to sell electricity, your smart meter will still measure exported electricity.
The electricity simply flows to the grid without payment.
So if export is enabled, it usually makes sense to register with an energy buyer so you are compensated.
Final Thoughts
The right export setting depends on:
- Your household consumption
- The size of your solar system
- Whether you have a battery
- The size of that battery
In general:
- Small batteries (≈10kWh or less): Export enabled usually makes sense
- Large batteries: Limiting export can maximise self-consumption
Understanding these small configuration choices can help ensure your solar system delivers the best possible return on investment.
If you would like independent advice on solar systems in Portugal, Sol Viva provides expert guidance for international homeowners installing solar in Portugal.
Sol Viva helps homeowners:
- Understand the right system size
- Review installer quotations
- Avoid common installation mistakes
- Maximise financial returns from solar
Start your solar journey now by completing a solar questionnaire.