Solar panel warranties explained: what Perth buyers actually need to know

Solar panels come with two distinct warranties that cover different things, last different periods, and are backed by different entities. Understanding both before you sign a contract protects you if a panel underperforms or fails years down the track.

The two solar panel warranties

1 — Product warranty (materials and workmanship)

What it covers: Physical defects in the panel itself — delamination, cell cracking from manufacturing defect, junction box failure, frame corrosion. Essentially: the panel was built incorrectly or failed prematurely due to a manufacturing fault.

What it does NOT cover: Physical damage from impact (hail, falling branches), damage from improper installation, normal degradation over time.

Typical duration: 10–15 years for mainstream panels; some premium brands offer 25 years.

Who backs it: The manufacturer. If the panel manufacturer ceases operations, the product warranty becomes unenforceable — you have no one to claim against.

2 — Performance guarantee (power output)

What it covers: Guarantees the panel will produce at least a specified percentage of its rated power after a given number of years. The guarantee is that degradation won't exceed certain rates.

Typical terms:

• End-of-year 1: ≥98% of rated power (covers initial light-induced degradation)
• End-of-year 10: ≥90% of rated power (1% average degradation/year)
• End-of-year 25 or 30: ≥80% or 82.6% of rated power

Some premium panels (using heterojunction technology) offer tighter guarantees: 30 years at 92% or better — reflecting the technology's lower annual degradation rate (approximately 0.26%/year vs standard 0.55%/year).

What "80% at 25 years" actually means:

If you buy a 400W panel with a standard performance guarantee:

• After 25 years, it must still produce ≥320W (80% of 400W)
• If it produces 295W at year 20 and your monitoring confirms this, you have a performance warranty claim

Who backs it: The manufacturer. Same caveat as the product warranty — a manufacturer that doesn't exist in 25 years can't pay a claim.

Making a performance warranty claim

Performance warranty claims are rare but procedurally demanding when they do arise:

What you need:

1. Evidence the panel is underperforming: monitoring data showing output, ideally with irradiance data to prove the test conditions (or an independent PV technician's report)
2. Panel serial numbers and model
3. Proof of purchase and installation date
4. Written claim to the manufacturer's Australian agent or direct to the manufacturer

Practical obstacles:

• Proving underperformance requires eliminating other causes: soiling, shading, inverter issues, wiring degradation
• Most manufacturers require the claim to go through the original installer or an authorised service partner
• A successful claim typically results in replacement panels, not cash

The "two-year consumer guarantee" advantage: In Australia, the Australian Consumer Law (ACL) provides a consumer guarantee independent of the product warranty that panels will last for a reasonable period. For a product sold as "lasting 25 years," ACL arguments have succeeded in recovering compensation even after manufacturer warranties expired. This is a legal avenue worth exploring if your installer or manufacturer is unresponsive.

What happens when a manufacturer exits Australia

This is the most practically relevant scenario for Perth buyers — and it's not theoretical.

LG Solar example: LG Solar exited the global solar market in 2022, ending production. LG panels installed before 2022 are no longer supported by the manufacturer. LG has appointed a warranty claims agent (different by country/distributor), but the process is more complex than claiming against an active manufacturer.

What this means for buyers:

• A 25-year product warranty from a manufacturer with no Australian presence may be unenforceable in practice, even if legally valid
• Favour manufacturers with established Australian operations, local service networks, and a long track record of standing behind claims

Questions to ask your installer:

• Who is the Australian distributor for this panel brand?
• Does the manufacturer have a local service centre or warranty agent in WA?
• Has the manufacturer been in the Australian market for at least 5 years?

Inverter warranty — a separate note

Your inverter has its own product warranty:

• Standard: 5 years (most mainstream brands)
• Extended: 10 years (available for purchase on many inverter models for $300–$800 at time of installation)
• SolarEdge: 12-year standard inverter warranty + 25-year power optimiser warranty

Inverters are more likely to need replacement within the system's 25-year life than panels. For long-term financial planning, factor in one inverter replacement (approximately $1,500–$3,000 for a 5kW unit) at around year 10–15 of your solar system's life.

What to check before signing your solar contract

• ✓ Product warranty duration (10yr minimum; 15–25yr preferred)
• ✓ Performance guarantee duration (25yr minimum) and end-point percentage (80%+)
• ✓ Manufacturer's Australian presence: distributor name, Australian contact
• ✓ Whether extended inverter warranty is included or available to add
• ✓ Who handles warranty claims: your installer, an agent, or direct to manufacturer?
• ✓ What the claims process looks like in writing (ask the installer to spell it out)

Warranty terms vary by manufacturer and model. Verify specific warranty terms in the panel datasheet before signing. Australian Consumer Law rights exist independently of manufacturer warranties — consult a consumer rights body if you encounter warranty disputes.