solar-panel-warranty-guide-panel-vs-inverter-vs-workmanship

The most common sales pitch line in all solar sales in India is probably "25-year warranty". It's also one of the most misunderstood. There is no single warranty for a solar system—there are at least three different warranties, each for a different component of the system, each for a different length of time, and each with a different company behind it. The difference is more important than the headline number because that determines if you'll get a replacement or a repair bill five years from now.

The warranty for panels

Each solar panel comes with two warranties:

Product warranty (typically 10-12 years): This applies to manufacturing defects (delamination, corrosion of the frame, failure of the junction box or simply a panel that fails to function because of a manufacturing defect). If a panel fails within this time frame because of an actual manufacturing problem, the manufacturer will replace or repair it.

Performance warranty (usually 25-30 years): This is the warranty that everyone talks about, but it does not imply that the panel is guaranteed to perform flawlessly for 25 years. It implies that the manufacturer will ensure that the panel will maintain a minimum percentage of the rated output at year 25, typically 80-87%, depending on the brand and panel technology. Each year, panels will degrade at a rate of approximately 0.4-0.6% per year, and the warranty for the performance of the panels is essentially a guarantee that the panels will not degrade any faster than the expected curve.

This difference is significant when it comes to claiming. A panel that is not producing as much power as expected is not necessarily a warranty issue; it must be measured to be less than the degradation curve for that year, and this is typically determined by the manufacturer or a certified testing agency, not the installer.

Components covered by the inverter warranty

The most common warranty claim is for the inverter, which typically has the shortest warranty period - standard inverter warranties in India last 5-10 years, compared to the panel's 25-year performance guarantee. String inverters are usually at the lower end of the range; some high-end and hybrid inverters provide 10-year warranties when bought at installation.

This is precisely why serious buyers negotiate inverter warranty extensions in advance, or plan for a potential inverter replacement at year 8-10 of a 25 year system life. It's not a fault in the technology—inverters have a lot more moving electronic components and a shorter natural service life than a panel, which is mostly passive glass and silicon.

Workmanship warranty—The one thing buyers don't ask 

This is the warranty on the installer's work – the mounting structure, cabling, earthing, waterproofing around roof penetrations, and installation quality. It is generally provided by the EPC (installer) company for 5-10 years in addition to the warranty of the panel manufacturer and the inverter manufacturer.

This is also the most likely warranty to be worthless if the installer goes under or decides to leave the company, because it is not supported by a big manufacturer, it is supported by the company that actually installed your system. Workmanship is a major portion of the real-world solar problems (leaking roofs, loose structures, corroded clamps) and is the warranty that is most important to review prior to signing a contract.

Questions to ask before purchasing

• Does the panel performance warranty come from the manufacturer or from the local distributor?
• Ask for the degradation table, not just "25 years," at years 10, 15, and 25.
• Will the inverter need to be replaced halfway through the panel's life span?
• If the installer goes out of business, who will honor the workmanship warranty? Is there any third-party support?
• Does the warranty document state the timeframe for a claim, or does it simply state “as per company policy”?

The typical "25-year warranty" claim typically includes a robust panel warranty, a short inverter warranty, and a workmanship warranty that is dependent on the installer and not supported by any large manufacturer. Before you sign anything, request these three things separately in writing, with the years and coverage terms for each (not just the number on the brochure).