What 'Tier 1' Solar Panels Really Mean — and Why It's Not a Quality Cert
Tier 1 = BloombergNEF's manufacturer bankability list · real panel quality is measured by IEC 61215 / IEC 61730 / Thai TIS · plus a checklist to audit the panel spec before you sign an EPC contract
Almost every solar quote in Thailand says 'Tier 1 panels' — but few explain that Tier 1 ranks the manufacturer's financial standing, not the quality of each panel. This page makes the distinction clear, summarises the standards that actually measure quality, and gives factory owners a checklist to audit any quote before signing.
Tier 1 is BloombergNEF's bankability ranking of panel manufacturers — the core criterion is that projects using the maker's panels obtained non-recourse bank financing, not any laboratory quality test. BNEF itself stresses Tier 1 is not a quality measure. Real panel quality is measured by IEC 61215 (durability and performance), IEC 61730 (safety) and Thailand's TIS (มอก.) standards. Before signing an EPC contract, always ask for serial numbers, the flash report, standards certificates and proof of an authorized distribution channel.
What Tier 1 actually is — a manufacturer finance list, not a panel quality cert
The shortest answer: Tier 1 is a quarterly 'bankability' list compiled by BloombergNEF (BNEF). The core criterion is that the manufacturer has had sizeable projects, using its own-brand panels, financed on a non-recourse basis by multiple banks or financial institutions over the past two years. In plain terms: 'banks are willing to lend against projects built with this brand.' It reflects business scale, manufacturing continuity, and the odds the company will still exist to honour a warranty claim in year 20.
What Tier 1 does NOT tell you: there is no laboratory testing of panels, no degradation measurement, no per-model production-line audit, and no guarantee that every panel carrying that maker's logo is genuine, full-grade product. BNEF itself states plainly that the list is not a measure of quality. So 'we use Tier 1 panels' in a quote is a good starting point — but it is not the final word on quality. The real quality yardsticks are in the next section.
Remember this formula: Tier 1 answers 'will the manufacturer survive until my warranty claim?' while IEC/TIS answers 'has this panel passed quality and safety testing?' A smart factory checks both — either one alone is not enough.
The standards that measure real panel quality: IEC 61215 / IEC 61730 / TIS
Panel quality is measured by independent-laboratory testing (e.g. TÜV, UL, Intertek) against the international IEC series, and Thailand's TIS (มอก.) standards which adopt the same IEC content. This table summarises what each standard tests and what it means for your factory.
| Standard | What it tests | What it means for your factory |
|---|---|---|
| IEC 61215 | Durability & performance: 200 thermal cycles, 1,000-hour damp heat, humidity-freeze, mechanical load, hail impact, hot-spot, UV exposure | The panel survives Thai heat, humidity and storms across the project life without abnormal degradation |
| IEC 61730 | Safety: construction requirements and testing for electric-shock protection, fire risk, mechanical strength, insulation | Reduces rooftop fire risk and crew hazard — a condition insurers look at |
| TIS (มอก.) | Thailand's industrial standards for PV modules, issued by TISI — content adopted from IEC 61215 (quality) and IEC 61730 (safety) | Confirms the model imported/sold in Thailand meets the same bar as the international standards; verifiable with TISI |
| Supplementary tests (site-dependent) | e.g. IEC 62804 (PID resistance) and IEC 61701 (salt-mist corrosion, for coastal sites) | Coastal factories (Samut Prakan, Rayong) should ask for the salt-mist result as an extra |
* Test parameters reference the publicly published IEC standard requirements — the exact standard edition certifying each panel model varies; always check the actual certificate for the model quoted. TIS details can be verified on the TISI website.
Thai standards authority: Thai Industrial Standards Institute (TISI)
Update 2 Oct 2026: cabinet approves making TIS 61730 Part 2-2567 mandatory for crystalline-silicon panels — awaiting Royal Gazette publication · panels with IEC test reports can register within 5 days
At its 29 Sep 2026 meeting the cabinet approved the Ministry of Industry's draft ministerial regulation — already vetted by the Office of the Council of State — and cleared it to proceed (official cabinet summary, item 5). The regulation requires crystalline-silicon PV modules (excluding panels built into other products) to comply with TIS 61730 Part 2-2567 (PV module safety qualification — requirements for testing), which covers electric-shock, leakage, reverse-current and abnormal-heating risks. In practice, manufacturers and importers must obtain a licence under the Industrial Product Standards law, and sellers may only sell licensed panels. TISI estimates around 200 manufacturers/importers are ready to comply. The draft went through public hearing on 20 May–18 Jun 2026 (47 respondents: 7 fully agreed, 24 agreed but asked for changes to the enforcement timeline/acceptance of test results, 16 disagreed) and takes effect the day after publication in the Royal Gazette — check the actual publication date before citing it in a contract. Still open: the ERC Office asked for guidance on panels already imported or mid-installation, which the cabinet told the Ministry of Industry to take into account — as of 1 Oct 2026 no such guidance has been published.
30 Sep 2026 government clarification (official): the Minister of Industry confirmed that imported panels already certified to IEC standards can submit their IEC test reports to TISI to register for the TIS standard — no re-testing, no more than 5 days, and no additional fee. During October TISI plans to issue 279 import licences covering 279 IEC-certified imported panel items. This cabinet resolution covers crystalline-silicon panels only; for inverters, cables and batteries the Ministry of Industry will consider standards step by step and take them to the cabinet later. What it means for buyers (our analysis): the bottleneck is not testing but whether the exact model you are buying is already on the licensed list — ask the seller for that model's TIS licence number. If an importer still hasn't applied when the process takes no more than 5 days, treat it as a warning sign. Specific guidance for panels already imported or mid-installation has still not been published as of 2 Oct 2026.
Timeline: from standard notice to enforcement
- 27 Dec 2024 — Ministry of Industry notice publishes TIS 61730 Part 2-2567 (a voluntary standard at that point)
- 20 May–18 Jun 2026 — TISI public hearing on the mandatory-standard regulation (47 respondents)
- 29 Sep 2026 — cabinet approves the draft regulation (already vetted by the Council of State) ✔
- 30 Sep 2026 — government/TISI clarify: panels with IEC test reports can register for TIS within 5 days, no re-test, no extra fee; 279 import licences due in October
- Next — publication in the Royal Gazette → in force the very next day, with no grace period in the draft; specific guidance for already-imported / mid-installation panels still pending from the Ministry of Industry (as of 2 Oct 2026)
Where is your factory in the process — what to do now (CapSolar's guidance, not an official rule)
| Project stage | What to do |
|---|---|
| Collecting quotes / not yet signed | Add a contract clause: the delivered panel model must hold a TISI licence under TIS 61730 Part 2-2567 by the delivery date (on top of IEC 61215/61730 certificates), and if the model cannot be legally sold once the rule takes effect, the seller swaps in a licensed model at no extra cost |
| Signed, panels not yet delivered / still in import | Get written confirmation from the EPC/importer on whether a licence has been applied for this model, and who carries the cost if delivery slips while waiting for it — TISI says panels with IEC test reports can register within 5 days, so ask the importer to file now and send you the licence number. Specific transition guidance for already-imported panels has not been published, so don't assume an exemption |
| Already installed and running | The draft regulates manufacture, import and sale; the government announcement does not address systems already installed — what to do is keep your existing document set complete (serials, flash report, IEC/TIS certificates), because you'll need it for warranty claims, system expansions and insurer reviews |
Official source: Government Public Relations Department (Thai) — solar panel safety standard announcement (29 Sep 2026) · Royal Thai Government (Thai) — cabinet meeting summary, 29 Sep 2026 (item 5) · Royal Thai Government (Thai) — IEC-certified panels can register for TIS within 5 days (30 Sep 2026)
Can a 'Tier 1' panel still be substandard? Grey-market red flags
Yes — and it happens several ways: factory seconds (B-grade) sold off cheaply, refurbished panels from old projects polished and re-stickered, counterfeits carrying a famous logo that never left the real factory, and genuine panels moved through unauthorized channels (grey imports) that void the manufacturer warranty. Every one of these can still print 'Tier 1' on a quote — because Tier 1 refers to the manufacturer, not the physical panel in front of you.
Red flags that should stop the conversation and trigger deeper checks (generic market patterns — no specific seller implied): a price suspiciously far below market · no serial numbers, or serials that don't match the paperwork · no flash report, or only a blurry photocopy · a warranty issued by the trader rather than the manufacturer or an authorized distributor · nameplate spec that doesn't match the datasheet · no IEC/TIS documents for that exact model (only a sibling model's) · polish marks, re-torqued frame screws or yellowed backsheets · a seller who can't explain the import channel. A substandard panel isn't just lost output — it is a direct fire risk on your factory roof. Read more in solar fire safety for Thai factories.
The 6-point checklist: audit the panel spec in an EPC quote before signing
Run all six on every quote — a straight-dealing EPC can answer every item within days. If any item gets deflected, that is information. And remember good panels alone aren't enough; the contractor must pass vetting too — see how to vet a solar EPC contractor.
| Check item | How to ask / verify |
|---|---|
| 1. Exact panel model named in the contract | Brand + model + wattage in writing, not just 'Tier 1 550W panel' — no 'or equivalent' clause without your written approval right |
| 2. IEC 61215 + IEC 61730 + TIS certificates for that model | Ask for certificate copies from an independent lab (TÜV/UL/Intertek) naming the exact quoted model; certificate numbers can be checked against the lab's database |
| 3. Serial numbers + manufacturer verification | Request the serial list for the delivery lot; most major manufacturers offer online or distributor serial verification — spot-check at least a sample before accepting delivery |
| 4. Flash report matching the serials | The flash report is the factory's measured output for each panel (Pmax, Voc, Isc at STC) — ask for the original file for the actual lot and spot-match serials on panels against the report |
| 5. Proof of an authorized channel | Ask for documentation that the panels come direct from the maker or via an authorized Thai distributor — genuine panels through the wrong channel can void the manufacturer warranty |
| 6. Warranty registered with the manufacturer | Have the EPC show the warranty registration in your project/company name — not parked under a middleman's name |
How to read 12/25/30-year warranties without getting fooled
One panel carries two very different warranties: (1) the product warranty — covering material and workmanship defects, typically around 12–15 years depending on model and maker; and (2) the performance warranty — promising output won't fall below a stated percentage at year 25–30 (e.g. linear degradation capped per year as written in the datasheet). The advertised '30 years' usually refers only to the latter — if a backsheet cracks in year 14 but the product warranty was 12 years, you are not covered. For the full degradation logic see solar panel degradation and lifespan, and the Thai-factory deep-dive at factory solar panel degradation and lifespan in a hot, humid climate.
Three questions to ask before signing: who actually services the claim (manufacturer, distributor or EPC)? Which conditions void the warranty (out-of-spec installation, missing maintenance records, wrong purchase channel)? And who pays the hidden claim costs (removal/re-installation labour, freight)? The most overlooked item is the O&M log — many manufacturers can reject a claim without documented periodic maintenance. See the solar maintenance guide and the system-wide insurance picture in solar insurance & warranties for factories.
Panels used in the Thai factory market — and CapSolar's approach
Thailand's C&I market runs mainly on panels from the global Tier 1 manufacturer group, whose cell-level specs and technology (TOPCon, bifacial, etc.) converge more every year — so the real differences for a factory buyer are the sourcing channel, a warranty that is actually claimable in Thailand, and the price-per-watt in that procurement cycle. For a brand-by-brand comparison see solar panel brand comparison for factories, and for price direction see the 2026 solar module price trend.
CapSolar's approach is plain: we use only panels from the Tier 1 manufacturer group, with IEC 61215 / IEC 61730 certificates for the exact model installed, sourced exclusively through authorized channels, with serials and flash reports checked on every lot before it goes on a roof — the same standard behind the 80+ MWp we have delivered across 150+ industrial projects for 100+ clients. We don't editorialise about individual brands, because the model and the lot matter more than the logo — our rule is 'verify the real documents, every time, no exceptions.'