Keep your green certificates with a battery or semi-off-grid?

Yes, if the design respects one rule. The green meter may only count what your certified panels produce. Adding a battery does not, by itself, end your right to green power certificates. Fluvius says so outright, and Brugel and SPW Energie set metering and inspection conditions, not a ban. Adding panels to the same installation, or letting grid power pass the green meter, can. For a farm or business with an older solar installation, a semi-off-grid system leaves the certified panels and their meter as they are. It adds new panels and a battery beside them.

Maybe you run a farm or a workshop with a large solar installation from 2011. It still earns green power certificates every month. Now the grid is full, the capacity tariff bites, or you want to keep working during a power cut. A battery or a semi-off-grid system makes sense. But installers and forums repeat the same warning. You "cannot expand" a certified installation "without losing those", one owner writes, "unless you get a separate inverter". Another chose a plug-in battery only because he did not want to "mess with the existing PV installation".

What most owners do not see is that both extremes cost money. Doing nothing keeps your site stuck at the power of its connection. Doing it wrong can cost the certificates for the remaining years, and the grid operator can claim back what it already paid. Where the meter or the reports are manipulated, Fluvius treats it as energy fraud, and VEKA can add a fine.

It can be done cleanly. At a semi-off-grid site in Wingene, keeping the Flemish green power certificates, where they apply, was part of the design. A battery of 150.4 kWh delivers 3 x 400 V at 63 A on its own. The grid only comes in as a back-up charger.

Do you lose your green power certificates if you add a battery?

No. A battery does not, by itself, end your right to green power certificates. Fluvius says so explicitly, even for a battery coupled on the DC side. Brugel and SPW Energie set conditions on the metering and the inspection. The rule behind all three is the same: the green meter may only register electricity from the certified panels.

So self-consumption is not the problem. Storing solar power for the evening does not take away the kWh your green meter has already counted. The problem starts when the battery can push grid power through that meter. Fluvius calls that energy fraud under the Flemish Energy Decree.

Is it a home installation rather than a business? Then read our article on adding a battery to an existing SMA or SolarEdge installation, with the home rules and back-up options.

Where can the battery go without touching the green meter?

The safest place is behind the green meter, on the side of your site: an AC-coupled battery with its own battery inverter. It stores what your site does not use and never passes the green meter. A battery on the DC side of a hybrid inverter sits in front of the meter. Then the meter must tell production and grid charging apart.

Fluvius puts the last row plainly. Power that a battery takes from the grid and then sends through the green meter can never earn minimum support. With a bidirectional green meter, the grid power drawn by the battery is subtracted from the count, so only solar production remains.

Large installations add one step. Above 25 kVA in Flanders, a new inverter with the same or lower power is allowed. A new inverter with more power first needs a grid study by Fluvius.

What may you change on an installation with green power certificates in Flanders?

In Flanders, Fluvius allows a battery, a repair after a defect and a hybrid inverter together with a battery. It does not allow extra panels on the certified installation. These rules come from the Fluvius explanatory note of 18 November 2024. Unless stated otherwise, it applies to installations of every size.

Every change goes to Fluvius within 30 calendar days. Above 10 kVA the production meter belongs to Fluvius and is read remotely and checked every day, so a change rarely goes unnoticed. Want more solar power than your connection allows? Our article on more solar panels than your connection allows explains the limits.

Can you go semi-off-grid and keep your green power certificates?

Yes, when the certified installation stays on the grid side, untouched. A semi-off-grid system is a second, separate system. New panels and a battery carry your site, and an automatic transfer switch connects the site either to the grid or to the island. The old panels keep feeding the grid through their own green meter.

Moving the certified panels into the island is a different story. In Flanders, grid operators must buy certificates at the minimum price from installations connected to their grid. The Flemish regulator states that this purchase duty does not apply to installations in island operation. Fluvius adds that it only pays the minimum support while the installation stays correctly connected to the grid.

The semi-off-grid design suits a business or farm on a standard 3 x 400 V connection, up to 75.6 kVA. A farm in Tielt works this way with a 123.2 kWh battery and 45 kVA of charging power. It is designed to take only 5% of its yearly consumption from the grid. A dairy farm in Londerzeel avoided a medium voltage cabin with solar panels, a wind turbine and a semi-off-grid battery system. That saved at least 60,000 euro from the start.

New to the terms? Our article on what off-grid and semi-off-grid really mean explains the difference.

Do you keep your green certificates in Wallonia when you add a battery?

In Wallonia, a battery does not change how certificates are calculated, but it is a change to your installation that must be checked. SPW Energie grants the certificates on the production you declare from the meters listed in your certificate of guarantee of origin.

• Who still receives them: solar installations above 10 kW. Installations of 10 kW or less no longer receive any support.
• Meter readings: every quarter you send the index of all meters listed in that certificate to SPW Energie.
• Inspections: an approved body checks the installation every year above 20 kW and every 5 years from 10 to 20 kW. It also checks after every change compared with the certificate.
• Minimum price: Elia must buy the certificates at a guaranteed 65 euro.
• Small Solwatt installations: an extension must be created as a new production unit to keep the certificates.

In practice, a battery between the panels and the certified meter changes what that meter measures. Have the approved body and SPW Energie confirm the new metering before the battery goes live. An AC-coupled battery on the site side leaves the certified meters alone. Still ask the approved body whether your certificate needs an update.

What do Brugel and Sibelga ask when you add a battery in Brussels?

In Brussels, it depends on where the battery connects. Is it on the production side, meaning on a hybrid inverter or between the panels and the green meter? Then you need a bidirectional MID green meter with two indexes. Elsewhere, the simple green meter can stay.

• With a bidirectional meter, you enter both indexes in your Sibelga account: production and the "grey" power the battery takes from the grid.
• A battery added after certification needs a new RGIE inspection (the electrical safety check), and you notify Sibelga of the change.
• The battery may not inject into the grid, except for flexibility or aggregation services.
• A battery combined with green production gives no guarantees of origin, because the grid operator cannot tell green injection from battery injection.
• Brugel may inspect a certified installation during its 10 years of eligibility, also on site.

Which mistakes cost a business its green power certificates?

Most lost certificates come from well-meant changes, not from the battery itself. These are the ones to avoid:

• Extra panels on the certified inverter "to use the free roof space" (Flanders: the right to certificates ends).
• A hybrid inverter without a battery, replacing an inverter that still works (not allowed in Flanders).
• A DC battery or a grid-charged battery behind a one-way green meter. Grid power then counts as green.
• Moving the certified panels into an island without written approval from the authority of your region.
• Forgetting the paperwork: the report to Fluvius within 30 days, or the new check in Wallonia and Brussels.
• Reading the battery meter instead of the green meter when you send your index (a trap Brugel names).

What happens when you ask us to add a battery around your certificates?

We start with your certified installation, not with the battery.

1. Step 1: Your installation. You send the inverter type, the green meter, the start date of the installation and your region. We check which rules apply to it.
2. Step 2: Design. We choose where the battery connects: AC-coupled on the site side, or a separate semi-off-grid island with its own panels.
3. Step 3: Installation. Our semi-off-grid installations run up to 75.6 kVA on a 3 x 400 V connection. For larger sites we design a business battery system instead. The new electrical inspection and the report to your grid operator follow the installation.
4. Step 4: Monitoring. You follow consumption and solar yield in clear data, as on the site in Wingene.