Choosing a reliable solar supplier

The hardware in a solar system is mostly commoditised. What separates a good system from a bad one — operating at year 8, year 15, year 22 — is the supplier. This guide covers how to evaluate the supplier before you commit.

Why this matters more than hardware

Panels from different tier-1 manufacturers perform similarly. Inverters from respected brands are broadly comparable. What varies hugely is:

• How well the system is designed for your specific site and load.
• How carefully the installation is executed.
• Whether the supplier answers the phone when you have a question in year 5.
• Whether warranty claims are handled quickly or get fought.
• Whether ongoing monitoring catches issues before they become expensive.

A good design with average hardware outperforms a bad design with premium hardware. And a system you can't get serviced is worth less than a system you can.

Basic checks

Before diving into engineering or warranty detail, run these first. Fail any and the conversation can end early:

Company registration and licences

Real business registration, not a Gmail address and a mobile number. Solar installation in most jurisdictions requires electrical contractor licences. Verify the licences are current and cover the scope of work.

Physical office

An office you can visit. Not a virtual address. Not a shared workspace listing. If a company won't tell you where they work, they won't be there in year 5.

Years in business

Solar has been a viable industry in most Asian markets for 10+ years. Suppliers active for 5+ years through multiple market cycles have demonstrated some durability. Brand-new operations aren't automatically bad, but they carry more risk.

Insurance

Public liability, professional indemnity, and ideally workmanship guarantee insurance. A supplier without insurance is putting all the risk on you.

Engineering depth

This is where serious suppliers separate from marketing-first operations.

Site survey before quote

A serious quote requires a site visit. Roof measurements, shading assessment, structural check, electrical panel inspection. Quotes issued "off satellite imagery" miss real-world constraints.

Specific yield modelling

Expected production should be modelled for your specific roof, not estimated from regional averages. The quote should show: peak sun hours assumed, orientation/tilt losses, shading losses, system efficiency factor, and monthly production breakdown.

Full bill of materials

Every component by specific make and model. Panels: manufacturer, model, wattage, efficiency rating, warranty terms. Inverter: manufacturer, model, capacity, warranty. Mounting: manufacturer, system type. Cabling, connectors, protection: specified.

Shading analysis

If your site has any shading potential (trees, adjacent buildings, chimneys), a dedicated shading analysis — not just "we had a look." Sun-path diagrams, seasonal variations, and shading-aware string layout.

The warranty reality check

Warranties sound similar on paper. The differences are in who handles claims, what's covered for how long, and whether labour is included.

A quality warranty package includes:

• Panel product warranty — 25 years (industry standard for tier-1).
• Panel performance warranty — typically 80–87% of rated output at year 25. Higher is better.
• Inverter warranty — 10–12 years standard, extensions to 20–25 years often available.
• Mounting system warranty — 10–25 years depending on manufacturer.
• Workmanship warranty — from the installer on their own work. 5–10 years is serious; 1–2 years is cosmetic.
• Labour coverage for warranty work — often missed. If a panel fails in year 12, is the labour to remove and replace it also covered, or just the panel itself?

Also important: who handles warranty claims — the installer directly, or do you have to contact the manufacturer in a different country? The answer determines how painful warranty work actually is.

References and track record

Ask for references from projects:

• Similar scale to yours.
• In the same geographic region.
• At least 3 years old (so you can ask about post-install service).
• Ideally at least one at 5+ years old.

When you call references, ask:

• Has the system performed as projected?
• Have you had any warranty issues? How were they handled?
• How responsive is the supplier now, years later?
• Would you use them again?

A supplier unwilling or unable to provide older references is telling you something.

The questions to ask

These questions separate serious operations from sales-first ones. The answers matter; the way the answers are given matters more.

1. "Can I see a sample proposal from a similar completed project?"
2. "Who does the engineering — you, or a subcontractor?"
3. "What happens if the inverter fails in year 8? Walk me through the process."
4. "How many systems have you installed in my region specifically?"
5. "What's your policy if real-world production falls short of the model?"
6. "Can you show me monthly production assumptions, not just annual?"
7. "Is installation done by your own team, or by a subcontractor? How is their work supervised?"
8. "What does ongoing monitoring look like after installation?"

Specific, detailed, prompt answers signal a real operation. Vague answers, evasions, or "we'll get back to you on that" signal otherwise.

Frequently asked questions