Solar and Battery Warranties Explained

A solar and battery system doesn’t have one warranty. It has several: a product warranty and a performance warranty on the panels, a warranty on the inverter, a warranty on the battery, and a workmanship guarantee on the installation itself. They come from different companies, last for different lengths of time and have different conditions. Knowing which is which is the most useful thing you can do before you buy, and the first thing to check if something goes wrong.

Key points

• Panels usually have two warranties: a product warranty for defects and a longer performance warranty for output.

• Inverters and batteries have their own manufacturer warranties, usually shorter than the panels’.

• Battery warranties typically set a term, an energy throughput limit and a minimum retained capacity.

• MCS-certified installers must guarantee their workmanship for at least two years, transferable and insured in case they stop trading.

• Most manufacturer warranties are claimed through the installer, and many require registration and correct installation.

• Keep your paperwork. It matters again when you sell the house.

Panel warranties: product and performance

Product warranty. Covers defects in materials and manufacture, such as a faulty junction box, delamination or a frame failing. If a panel is defective within the term, the manufacturer repairs or replaces it.

Performance warranty. Covers output. All panels lose a little output each year. The performance warranty guarantees the panel will still produce at least a stated share of its original rated output after a set number of years, usually stated year by year on the datasheet. The performance term is usually longer than the product term.

The exact terms vary by manufacturer and model, so check the datasheet and warranty document for the panels in your quote.

Inverter warranties

The inverter does more work than any other part of the system and is the part most likely to need replacing during the life of the panels. Its manufacturer warranty is usually shorter than the panel warranties, and some manufacturers offer extensions if you register the product.

If your inverter fails out of warranty, our inverter replacement page explains the options, and our guide to the signs your inverter is failing covers what to look for.

Battery warranties

Battery warranties are structured differently. They usually set three limits and end at whichever comes first:

1. A term in years. Some also set an outer limit from the date of manufacture.

2. An energy throughput limit. The total amount of electricity the battery is warranted to put through. A battery cycled hard every day reaches it sooner.

3. A minimum retained capacity. The share of its original capacity the battery is guaranteed to keep, commonly around 70 per cent by the end of the term.

Battery warranties also often have conditions about where the battery is installed, such as ventilation and clearance, and some depend on the battery staying connected to the internet for updates. Our guide to how long solar batteries last explains these in more detail.

Workmanship: the installer’s guarantee

Product warranties cover the equipment. A workmanship guarantee covers the installation: the roof fixings, the cabling, the connections and the commissioning.

MCS requires certified installers to guarantee their workmanship on domestic installations for at least two years. The guarantee must be transferable to a new owner, and it must be insured so that it will still be honoured if the installer stops trading. That insurance is often called an insurance-backed guarantee (IBG). Many installers offer longer workmanship guarantees than the minimum, so check what your quote includes.

Our guide to what to do if your solar installer has gone bust explains how to claim if your installer is no longer trading.

How to keep your warranties valid

• Use an MCS-certified installer, and keep your MCS certificate.

• Register the products where the manufacturer requires it. Some extend the warranty if you do.

• Keep the system online. Some battery and inverter warranties depend on monitoring and firmware updates.

• Don’t let anyone else alter the system without checking the effect on the warranties.

• Clean and maintain it properly. Pressure washers and abrasive tools can damage panels. Our guide to whether solar panels need cleaning explains the safe way.

• Keep the paperwork together: the MCS certificate, warranty documents, datasheets, commissioning records and your installer’s guarantee.

How to make a claim

Most manufacturers handle warranty claims through the installer or distributor rather than directly with homeowners. The installer diagnoses the fault, provides evidence such as serial numbers and monitoring data, and arranges the replacement.

If the installer is no longer trading, the manufacturer warranty still exists; another installer can usually handle the claim for you. The installer’s own workmanship guarantee is then covered by its insurance.

Buying or selling a house with solar

Warranties and guarantees are usually transferable, but only if the paperwork goes with the house. Our guide to buying a house with solar panels lists what to ask the seller for.

Frequently asked questions

How long are solar panel warranties?

It depends on the manufacturer. Panels usually have a product warranty and a longer performance warranty, both set out on the datasheet.

What does a solar battery warranty cover?

Defects, and a minimum retained capacity over a set term, subject to an energy throughput limit. It ends at whichever limit is reached first.

Is the installation covered as well as the equipment?

Yes. MCS installers must give at least a two-year workmanship guarantee on domestic installations, transferable and insured.

Who do I claim through?

Usually your installer, who deals with the manufacturer. If your installer has stopped trading, another installer can help.

Are warranties transferable if I sell my house?

Usually, as long as the documents go with the property.

Request a solar and battery quotation. Your quote will set out the warranties on every product and on our workmanship.