Thailand Solar Panel TIS Rule: Cabinet Approved (Sep 2026)

Thailand is moving solar-panel safety from a voluntary standard to a compulsory one. This article explains — in plain language — where the rule stands now, who it actually applies to, what the standard tests, and the question we get asked most: "If I already installed solar, do I have to tear it out?"

🏷️What is TIS (มอก.) — and "general" vs "compulsory"

TIS (Thai Industrial Standard, "มอก.") is a certification issued by the Thai Industrial Standards Institute (สมอ.) confirming a product passed required tests. There are two kinds: a "general" standard is voluntary — a maker can apply for it but isn't forced to. A "compulsory" standard is backed by law: it becomes illegal to manufacture, import, or sell that product without a TIS licence. Solar panels have been on the voluntary list for years. What's changing is that panel safety is moving to the compulsory list.

📅Timeline: where the TIS rule stands

👥Who the rule applies to

• Covers crystalline-silicon solar panels — not panels built into other products.
• Manufacturers and importers must hold a TIS licence for each panel they make or import.
• Sellers may only sell licensed panels that meet the standard.
• IEC-certified panels: TISI accepts the IEC test results, so a TIS licence can be issued within 5 working days with no re-testing.

🔬What does TIS test to pass?

A solar panel must pass two TIS books, built directly on the international IEC standards. Think of them as two different questions: "Does it still make power after years of abuse?" and "Is it safe — no shocks, no fire?"

TIS / IEC 61215 (performance) puts a panel through accelerated ageing, then checks it still makes power. It must keep at least 95% of its rated output after:

• Damp heat — 85°C at 85% humidity for 1,000 hours
• Temperature cycling — −40°C to +85°C, 200 cycles
• Mechanical load — ~2,400–5,400 Pa of wind/snow pressure
• Hail impact — a 25 mm ice ball at ~23 m/s
• Hot-spot from partial shade (e.g. leaves, bird droppings)

TIS / IEC 61730 (safety) — the book becoming compulsory — checks that no one gets shocked and the panel won't start a fire:

• Wet-leakage current — ≤50 μA/kV when wet
• Dielectric withstand + impulse voltage (lightning/surge)
• Ground / equipotential continuity
• Sharp-edge test (safe to handle and install)
• Fire / flame-spread class (A / B / C)

This is why cheap, uncertified panels are a real risk: wet-leakage, hot-spot and flame-spread failures lead to exactly the hazards the government cited when approving the rule — electric shock, current leakage, heat build-up and fire.

🏠Already installed solar — do you have to remove it?

Short answer: no. The law controls three actions only — manufacturing, importing, and selling. Its target is makers, importers, and shops, not end-users who already own and operate a system. So a home or business that installed solar before the enforcement date is not committing an offence, and this type of compulsory-standard law does not reach back to order already-installed systems torn out. (For full legal certainty on your specific case, confirm with สมอ. 1441.)

One open point: when the Cabinet approved the rule, the Energy Regulatory Commission (ERC) asked for clear guidance on panels that were already imported, or are mid-installation, before the rule takes effect. The Industry Ministry has taken this away to work on — so if your project is being installed right now, ask your installer to confirm the panel model's TIS status.

That said, the change still touches existing systems in three indirect ways:

• Repairs & replacements: if a panel needs replacing after the date, the new panel you buy must carry TIS — shops won't be allowed to sell non-TIS panels.
• Resale & insurance: when you sell the property or arrange insurance / ESG reporting, certified equipment with documentation is an advantage.
• Old stock: any non-TIS panels still sitting in a shop's inventory can't legally be sold after the deadline — this affects installers more than homeowners.

🔌What other equipment is next?

Panels go first, but the Industry Ministry has announced plans to add more PV system equipment to the controlled list. Items named include:

• DC circuit breakers
• Fuses for PV systems
• PV cables
• Lithium batteries for energy storage
• PV combiner boxes
• DC connectors (MC4)

Grid-tied inverters already have their own separate standard (TIS 2607-2563).

🔍How to spot a panel that has TIS

• Look for the official TIS mark (a diamond-shaped symbol) printed on the panel label, alongside a licence number.
• The label should reference the standard number — e.g. TIS 61730 and/or TIS 61215.
• An IEC 61215 / IEC 61730 test report is the foundation — TIS is built on the same tests, and TISI accepts IEC results to issue a TIS licence within 5 working days. Once the rule is in force, ask the supplier for the TIS licence of the exact model as well.
• Verify a brand or importer in the สมอ. licence database (a.tisi.go.th) or by calling 1441.