What Voids a Solar Warranty

The most common causes of voided solar warranties are: installation by a non-MCS-certified contractor, unauthorised modifications to the system, physical damage caused by improper maintenance, and failure to obtain required planning permissions.

Non-certified installation

Panel and battery manufacturers require installation by a certified installer — in the UK, that means MCS accreditation. A system installed by an unaccredited contractor, however competent, typically does not qualify for the full product or performance warranty. It also cannot register for SEG export payments.

Unauthorised modifications

Adding panels to an existing string inverter beyond its rated capacity, connecting a battery incompatible with the inverter firmware, or bypassing safety disconnects voids both the product warranty and creates safety risks. Any additions should be assessed and carried out by a qualified installer.

Improper cleaning or maintenance

Using abrasive cleaning products, pressure washers at close range, or walking on panels to access them can cause microcracks and surface damage that voids the product warranty. Panel cleaning, when needed, should use soft brushes and clean water — or be left to a professional.

Planning permission failures

Most residential solar installations fall within permitted development rights and do not need planning permission. Exceptions include listed buildings, conservation areas, and systems on flat roofs that extend above the roof line. Installing without permission where required can result in an enforcement notice and insurance complications — quite separate from the warranty question.

What does not void the warranty

Normal soiling and gradual degradation within the performance warranty specification do not void it. Nor does a change of property ownership — warranties follow the system, not the original purchaser, and should transfer with the property.