How to choose a solar installer in Phuket (without getting burned)

Solar panels are largely a commodity. The company that bolts them to your roof is not. Here is how to judge an installer before you pay a deposit — the questions to ask, the answers that should worry you, and what a proper quote actually looks like.

Why the installer matters more than the panel brand

Most buyers begin by researching panels. It is the wrong place to start. Mainstream modules from established manufacturers are broadly similar in efficiency, degradation rate and warranty terms — the differences are real but small, and rarely decide whether a system performs well ten years from now.

What varies enormously is workmanship and aftercare. Roof penetrations that were sealed properly or were not. Mounting rails specified for coastal conditions or bought on price. Cable runs protected from UV, or left draped across hot tiles. String design that accounts for the shadow of the water tank, or does not. An inverter configured correctly at commissioning, or left on default settings. And, when something eventually goes wrong, a company that answers the phone.

Two identical bills of materials, installed by two different companies, can produce meaningfully different output and very different experiences over 25 years. That is the risk you are actually buying against.

Questions to ask before you sign

Ask these of every company you speak to, including us. Note not only the answers but how readily they are given.

1. Exactly which panels and inverter, in writing?

You want make, model number and wattage on the quotation, not a category. "Tier 1" is a financial classification of manufacturers, not a quality grade for the product on your roof, and it commits the installer to nothing. Named equipment lets you research it and holds them to what they promised.

2. Who physically does the installation?

Some companies install with their own employed teams; others sell the job and subcontract it. Subcontracting is not automatically bad, but you should know which it is, because it determines who is on your roof and who is accountable for the workmanship.

3. What does the workmanship warranty cover, and for how long?

Product warranties come from the manufacturer. Workmanship — mounting, waterproofing, cabling, labour to diagnose and fix — comes from the installer, and it is the one people forget to ask about. Get the term and the scope in writing, including whether labour and call-out are included.

4. Who handles a manufacturer warranty claim?

If a panel or an inverter fails in year seven, who registers the claim, who removes and refits the hardware, and who pays for that labour? A good installer manages the process for you. Ask them to describe it step by step.

5. Do you have a local office I can visit?

A physical address in Phuket that you can walk into is one of the cheapest pieces of due diligence available. Visit it. Companies operating from elsewhere can and do install here, but your ability to get someone back on the roof falls sharply with distance.

6. How long have you been trading?

Trading history is not a guarantee of quality, but it is evidence that the company survives its own mistakes rather than dissolving. Ask for the registered company name and check it is the same entity you are contracting with and paying.

7. What happens if the system underperforms?

Ask what annual output the design assumes, what performance ratio they design to, and what the remedy is if the system falls short. A serious installer will have a considered answer; a vague one is telling you the estimate was decorative.

What Phuket does to a badly built system

Island installations face conditions that inland ones do not, and shortcuts here surface within a few years rather than a few decades.

• Salt air corrosion. Airborne salt attacks fasteners, rails, clamps and enclosures. Appropriate stainless and marine-grade components cost more than the generic equivalents, and it is a common place to cut cost invisibly — nothing looks different on handover day.
• Mounting hardware and fixings. Fixings must suit the roof structure and be rated for the loads, not simply be whatever was on the van. Ask what is being fixed into, and how.
• Waterproofing. Tile and metal roofs need entirely different approaches. On tile, the detail around each penetration decides whether you get a leak in the first heavy monsoon; on metal sheet, it comes down to correct clamps or brackets and proper sealing at every screw.
• Wind loading. Arrays act as sails. Rail spans, clamp spacing and edge zones all matter, particularly on exposed coastal or hilltop properties.
• Monsoon rainfall. Sustained rain and heavy cloud also affect realistic yield expectations. A design based on optimistic national averages rather than southern Thailand conditions will overpromise — see our honest look at whether solar is worth it in Thailand for the numbers.

Red flags

None of these proves a company is bad. Each is a reason to slow down and ask more questions.

• Equipment described only as "tier 1" or "premium" with no make or model named on the quote.
• Pressure to sign today. Discounts that expire at the end of the visit exist to prevent comparison, not to save you money. A genuine price is still there next week.
• A deposit requested to a personal bank account. Payment should go to the registered company, against an invoice bearing that company's details.
• No written scope of works. If the electrical work, mounting method, protection devices and paperwork are not written down, they are not agreed.
• A promise to eliminate your bill entirely. Without storage, solar only offsets consumption while the sun is up. Any claim to wipe out a bill tells you about the salesperson, not the system.
• No local address, or an address that turns out to be a mailbox.
• A price dramatically below everyone else. Occasionally that is efficiency. More often something has been removed — corrosion-resistant fixings, protection devices, proper commissioning, or the margin that funds coming back when you call.

What a good quote contains

A quotation you can rely on should set out, in writing:

• Panel make, model, wattage and quantity; inverter make, model and rating; battery details if included.
• Total system size in kWp, and the estimated annual output with the assumptions behind it.
• Mounting system and fixing method for your specific roof type.
• Electrical scope: cabling, isolators, surge and earth protection, and any consumer unit work.
• Monitoring: what is supplied and who sets it up.
• Warranties, separated clearly into product and workmanship, each with a term.
• Whether utility applications and paperwork are handled, and by whom.
• Payment schedule, timescale, and what is explicitly excluded.

If two quotes differ by a large sum, this is usually where the difference lives — not in the panels, but in what has quietly been left out of the scope.

The checklist to take to every quote

Check	What you are looking for
Named equipment	Make, model and wattage of panels and inverter, written on the quote
Who installs	Own team or subcontractor — stated plainly
Workmanship warranty	Scope and term in writing, labour included or not
Warranty handling	A described process for making a manufacturer claim
Local presence	A physical office you can visit, and a registered company name
Trading history	How long the company has operated in Thailand
Output assumptions	Annual yield figure, stated assumptions, southern Thailand conditions
Coastal specification	Corrosion-resistant fixings and mounting suited to your roof
Waterproofing detail	A specific method for tile or metal, not a generic answer
Written scope	Electrical work, protection, monitoring, exclusions, payment stages
Payment route	Company account and company invoice, never a personal account
Aftercare	Who to call, response expectations, and whether they service what they sell

Take it to three companies and the differences become obvious quickly. The point is not to catch anybody out — it is to make sure you are comparing the same thing, because a cheaper quote for a smaller scope is not a cheaper system.

Where we stand

For transparency: TAE 2020 (Thailand) Ltd. has operated from Kathu, Phuket since 2020, with over a decade of combined industry experience across the team. We are an official Huawei agent in Thailand and also work with Deye, LVTopsun, Longi and Jinko. Our office is a real one and you are welcome to visit — you can read more about us.

We would rather you used this checklist on everyone, including us, than took anyone's word for it. If you want a quote written the way this article describes, for a home or a business, get in touch — and if solar does not make sense for your property, we will tell you that instead.