What warranties come with solar panels, batteries and inverters?

A solar system usually comes with several separate warranties. The manufacturers give product warranties against defects in the panels, inverter and battery. Panels also have a performance warranty on how much power they keep producing. Your installer gives a workmanship warranty on the installation itself. Under the Renewable Energy Consumer Code (RECC), members must give a written workmanship guarantee of at least two years at no extra cost, and back it with insurance in case they stop trading.

• RECC's Consumer Code says workmanship guarantees must last at least 2 years and transfer to the new owner if you move home.
• RECC members must make sure the full term of the workmanship guarantee is honoured if they stop trading, through an insurance-backed guarantee.
• Under the RECC Code, a deposit should never exceed 25% of the estimated cost, and deposits must be insured.
• AIKO's Neostar 2P+ datasheet guarantees no more than 1% power loss in year one and no more than 0.35% a year after that, to 88.85% at year 30.
• Tesla's UK warranty for Powerwall covers 10 years and guarantees 80% energy retention at 10 years.

What's the difference between a product warranty and a performance warranty?

A product warranty (sometimes called a materials warranty) covers faults in the item itself, such as a failed junction box or delaminating glass. A performance warranty (or power warranty) promises the panel will still produce at least a set percentage of its rated output after a given number of years.

The two are often different lengths, and they can vary between models from the same manufacturer. LONGi’s datasheet library shows 15-, 25- and 30-year material warranties across its current panels, all with 30-year power warranties. AIKO's Neostar 2P+ datasheet lists a 15-year product warranty, extendable to 25 years, and a 30-year performance warranty. That's why the exact model on your quote matters. MCS's pre-sale standard requires an installer to give you the manufacturer's datasheet for the proposed panels, inverter and any battery before you sign.

How much do solar panels degrade?

All panels lose a little output over time. The performance warranty sets the limit. AIKO's Neostar 2P+ datasheet, for example, guarantees no more than 1% loss in the first year and no more than 0.35% a year from years 2 to 30. Its warranty curve shows at least 90.6% of rated output at year 25 and 88.85% at year 30. Other models have their own figures on their datasheets.

MCS's generation estimate covers the first year only. MCS 032 says it doesn't reflect later degradation of panels or batteries.

What warranties come with inverters and batteries?

Inverters and batteries have their own manufacturer warranties, usually shorter than panel warranties. The Energy Saving Trust notes that a battery's lifespan is shorter than solar panels', and puts the typical battery lifespan at about 10 to 12 years.

Battery warranties normally guarantee capacity as well as freedom from defects. Tesla's Powerwall warranty is a good example of what to look for:

• 10 years free from defects from the installation date
• in the UK, 80% energy retention at 10 years (of the 13.5 kWh rated capacity), with unlimited cycles for solar self-consumption, time-based control and backup
• other uses capped at 37.8 MWh of total throughput
• Tesla needs to update the battery remotely, so if it isn't connected to the internet or registered, Tesla may not honour the full 10 years, though it says it will always honour at least four years

Before you sign, MCS 032 requires an installer to tell you the warranties on the system and its storage capacity, including any limits on degradation, cycles or energy throughput, and how the battery shows its remaining capacity.

What is a workmanship warranty?

A workmanship warranty covers faults caused by the installation rather than the products. Examples include a leaking roof penetration, a loose fixing or a wiring fault. By law, services must be carried out with reasonable care and skill under the Consumer Rights Act 2015. The RECC Consumer Code (version 9, 1 July 2026) goes further. Members must give a written guarantee against faults arising from the installation, at no extra cost, valid for at least two years and transferable to the new owner if you sell your home.

RECC also covers two other kinds of guarantee. An output guarantee is optional, and if an installer offers one they must make the conditions clear. With an extended guarantee, the installer must tell you it's optional, who provides it, what it costs and what the main benefits are.

What happens if the installer goes out of business?

This is where insurance-backed guarantees come in. Under the RECC Code, members must arrange an insurance-backed workmanship guarantee so the full term is honoured if they become insolvent or stop trading. Deposits and any advance payments must also be insured, so another member can complete your contract at no extra cost. The deposit should be a reasonable percentage of the cost and must not exceed 25% under any circumstances.

To find out who insures your installation, RECC suggests checking your installer's paperwork or your MCS certificate for the insurer's name. Many insurers ask for defects to be reported within 30 days of discovery, so don't sit on a problem.

MCS is strengthening this. Under its redeveloped installer scheme, which installers are moving to through 2026 and into 2027, every installer will need to buy an MCS-approved financial protection product for their customers. MCS says these give at least six years' cover from installation, with excess capped at £250. They cover cases where the installer goes bankrupt, retires or refuses to fix a problem, or where there's a design failure.

What warranties does The Solar House provide?

We're MCS certified (certification no. NIC200098), an NICEIC Approved Contractor and a member of RECC. The warranties on the products we fit are:

• LONGi EcoLife panels (LR7-54HVB): 30-year product and 30-year performance warranty, per LONGi’s warranty for that model. We also add a 30-year LONGi panel replacement warranty that covers labour and access costs.
• AIKO Neostar 2S (A465-MAH54Mb) and JA Solar DeepBlue 4.0 Pro (JAM60D41) panels: 25-year product and 30-year performance warranty, as stated in the manufacturers’ warranty documents we issue with each quote.
• GoodWe hybrid inverters and GoodWe Lynx D batteries: 10 years.
• Tesla Powerwall 3 and Powerwall 3 Expansion: 10 years.
• EcoFlow: 15 years on the products we've fitted.
• Our own installation work: a 5-year workmanship warranty, set out on your quote.

Our deposit is never more than 25% and is protected, and the final payment is due on completion.

How do I make a warranty claim?

Start with your installer. MCS says to explain the problem and what you'd like to happen, and that 14 days is a reasonable maximum time to expect a response. If it isn't resolved, you can complain to MCS, which will acknowledge your complaint within 5 working days. For eligible disputes, MCS also funds a free alternative dispute resolution service.

Keep your handover pack and your MCS certificate together. MCS says installers should issue the certificate within 10 days of commissioning. For more on looking after your system, see our FAQs.

If you'd like to go through the warranty documents for a specific panel, inverter or battery, visit a showroom or ask the team. We're happy to show you the paperwork before you decide.