Solar System Flooded? What to Do Before, During and After the Water

Between 19 and 21 November 2025, Hat Yai received about 630 mm of rain, with about 335 mm on 21 November alone, and water reached about 2.5 meters in some areas. Most homes and businesses with solar have the inverter, control box or batteries mounted on a ground-floor wall — well within reach of floodwater.

This article runs in time order: before the water arrives, during the flood, and after it recedes, then finishes with how to design a system for flood-prone sites. If your area is flooding right now, read the "during the flood" section first.

First: panels keep producing power even when the grid is cut

During floods the utility often cuts power to the area, so many people assume there's no electricity in the house. With solar, that isn't entirely true. The panels on the roof generate DC power whenever there's light, even under cloud, so the DC cables running down to the control box and inverter are still live.

The protection that stops the inverter supplying the house during an outage does not make the panel side dead. And if there's a battery, the cables between the battery and the inverter are live too. Inverter manufacturers' own manuals warn that the inverter's components and cables carry high voltage, and that DC cables connected to a battery may be live.

Before the water arrives: shut down following the manufacturer's procedure

If there's advance warning and the equipment is still dry, shutting the system down correctly reduces the risk considerably. The right procedure varies by brand and model, so follow the manual for the equipment actually installed, or the shutdown label fixed next to the inverter or switchboard.

The commonly used sequence for a rooftop system looks roughly like this:

1. 1Switch off the AC breaker that connects the inverter to the house switchboard.
2. 2Switch off the house's main breaker.
3. 3Switch off the DC isolator next to the inverter.
4. 4If there's a battery, shut it down following that battery model's manual.

Only do this when the floor is dry, your hands are dry and you can reach the switches safely. Never go on the roof in a storm. If you're unsure of the steps, call your installer before touching anything — switching off in the wrong order or with wet hands is riskier than not switching off at all.

If your home is in a flood-prone area, something worth doing today: photograph the shutdown label and keep it on your phone, and make sure at least one other person in the house knows where each switch is.

During the flood: keep away

• If the water has reached the inverter, control box or battery, don't go in to switch anything off, and don't wade through that room.
• Keep children and pets away from the area.
• If you smell burning, see smoke or hear unusual sounds from the battery, leave the building and call the fire service.
• Tell your installer the system has been flooded, so an inspection can be planned as soon as the water drops and the site is safe to reach.

After the water drops: don't switch the system back on yourself

This is where repeat damage happens most often. An inverter that has dried out and looks fine from the outside can still hold moisture or silt on its circuit boards and terminals. Switching the system straight back on risks electric shock and short circuits, and can turn equipment that could have been repaired into a write-off.

Guidance from Australia's Clean Energy Council during major floods in Queensland says the system should not be switched back on until it has been checked by an accredited installer or licensed electrician, because moisture may be present in switches and other components, and that submerged inverters will likely need replacing. A U.S. Department of Energy guide states that any solar system components that have been submerged need to be replaced, including the inverter, switchgear, meters and other hardware.

What the technician should check before re-energizing:

• How high the water actually reached relative to each piece of equipment, using the watermark on the wall.
• The inverter, battery, control box, surge protection devices and breakers that were below the waterline.
• Insulation resistance of the DC cabling and connectors that were underwater.
• The earthing system and the house switchboard, which an electrician should check at the same time.
• Rooftop panels usually escape the floodwater, but if there was a storm as well, check the mounting and look for cracked panels at the same time.

Will insurance or warranty cover it?

Manufacturer warranties generally cover manufacturing defects, not external events. For example, Solis's warranty terms explicitly exclude damage from lightning, flood, power surges, fire and force majeure. For other brands, check the warranty document for the model actually installed.

An installer's workmanship warranty covers defects in the installation, not natural disasters. So the route that may actually help is usually your home or business property insurance — and flood cover varies from policy to policy.

1. 1Check whether your policy covers flood, and whether the solar system is listed as insured property.
2. 2If the solar was installed after you took out the policy, ask your insurer to add it.
3. 3Before removing or discarding damaged equipment, photograph the watermark, the model and serial number labels, and keep the original quote and tax invoice.
4. 4Ask the technician for a written inspection report to support the claim.

Designing for flood-prone sites

Rooftop panels are rarely the problem. What gets damaged is the equipment on the ground floor — and that's solved by choosing its position on installation day.

• Mount the inverter, control box and battery above the highest flood level seen in the area, with a margin. The U.S. Department of Energy guidance follows the same principle: raising equipment above the expected flood level prevents a total loss.
• In a two-story house, putting the equipment upstairs or high on a wall above the flood line is often the simplest option — but ventilation and cable runs need to be considered too.
• Batteries must be placed at the clearances and locations the manufacturer specifies, and not on a ground floor that has flooded before.
• Put the DC isolator and breakers somewhere you can reach without wading, and fix a clear shutdown label beside them.
• An ingress rating on an inverter spec sheet, such as IP65, means protection against dust and water jets or spray — it doesn't mean the unit can be submerged.

If you're in Hat Yai or anywhere water has entered the house before, tell us the highest flood level when we first discuss the job. Equipment placement needs to be agreed before installation; moving it later costs extra labor and cable.