Solar backup that failed in a power cut

What the April 2025 blackout showed

In the Iberian blackout of April 2025, it took about 12 h for REN to restore all substations, and full normalisation only came the next morning.² That day, many homes with panels saw their system switch off along with the grid. That's what a system without backup does, for the safety of people working on the grid.

Why backup can fail

There are several possible causes, and some come together:

• The inverter has no backup output, or it has one that isn't connected.
• The backup circuit was never installed: the battery is there, but the home isn't connected to it during the cut.
• The backup function is switched off in the inverter or app settings.
• The battery was flat, reserved for another use or faulty.
• The appliances on the backup circuit ask for more than the system can give.

Sometimes correcting the settings is enough; other times the wiring or the equipment has to change. Only an assessment tells which case is yours.

What we check

• The brand, model and settings of the inverter and battery.
• Whether there's a backup output and how it's wired to the consumer unit.
• Which circuits should stay on in a cut, such as the fridge, lighting or internet.
• The app history, if you still have access.

If the current inverter can't do backup, the quote may include swapping it for a hybrid inverter. If you don't have a battery yet, see battery for solar panels.

From request to repair

Tell us in your request what happened in the cut and what equipment you have. We reply within 48 h, assess the system and send a written quote, with the price stated before you go ahead. We only go ahead with your agreement.