UGT vs TPA (Direct PPA): Which Green-Power Route Should Your Thai Factory Choose? 9-dimension comparison + decision tree
When the roof isn't enough, there are two main off-site green-power routes: UGT (through the utility) and TPA / Direct PPA (a bilateral contract delivered by wheeling). This page compares them head-to-head so you can decide which fits — it links out for the mechanism details rather than re-explaining each.
UGT (Utility Green Tariff) lets a factory buy standardized green power from MEA/PEA on one bill at an ERC-set rate — simple and fast. TPA (Third-Party Access) means a Direct PPA wheeled across the grid for a wheeling charge — more flexible and potentially cheaper at scale, but more complex and, as of 2026, still a limited pilot. Choose UGT for speed; TPA for scale.
30-second summary: UGT vs TPA / Direct PPA
| Dimension | UGT (utility route) | TPA / Direct PPA |
|---|---|---|
| You contract with | The utility (MEA/PEA) | The generator (bilateral) |
| Speed / simplicity | High — subscribe, no negotiation | Low — negotiation + approvals |
| Price / flexibility | Fixed at an ERC-set rate* | Negotiable + a wheeling charge* |
| Status (2026) | Open by enrollment / quota | A limited pilot* |
| Best fit | Small–mid load wanting speed | Large load wanting price control |
*UGT rate, wheeling charge and TPA eligibility are set by ERC / EGAT / the utilities and change by period — verify current terms with ERC / your utility.
Can an ordinary factory use Direct PPA in 2026? — Not yet
This is the point most pages miss: Thailand's Direct-PPA-via-Third-Party-Access (TPA) pilot, as of 2026, is open only to “BOI-promoted data centers with an IT base load of at least 50 MW per building,” under a 2,000 MW framework (the National Energy Policy Council, NEPC, approved it on 25 June 2024; the ERC released draft regulations on 3 Oct 2025). An ordinary manufacturing factory does not yet qualify to sign a freely-wheeled Direct PPA in this pilot. If you're a typical factory wanting green power now, the routes that actually work are: (1) maximize rooftop solar first, then (2) top up with UGT2. TPA access may broaden later — verify current eligibility with ERC/EGAT.
What each route is (in brief — read the full pillar for details)
UGT — the utility route
UGT (Utility Green Tariff) means buying standardized renewable power through the MEA/PEA utility with the certificate bundled on one bill — no negotiation needed. Read the full mechanism in the UGT2 factory guide.
TPA / Direct PPA — the bilateral route
TPA (Third-Party Access — the right of a third party to use the grid) lets you sign a Direct PPA (bilateral Power Purchase Agreement) with a private generator, with the power delivered across the grid via wheeling (transporting power over the network for a fee). Read the full mechanism in Wheeling & Third-Party Access, and the contract basics in What is a PPA and the Direct PPA factory guide.
Important: as of 2026, Third-Party Access in Thailand is still a "limited pilot," not a fully liberalized market. The Direct-PPA-via-TPA pilot (the National Energy Policy Council approved a 2,000 MW framework in June 2024, beginning with BOI-promoted data centers) and the ERC's draft Direct-PPA regulations (released 3 Oct 2025) are recent; the broader TPA Code remains under consultation. A typical factory cannot freely wheel power today — verify eligibility with ERC/EGAT.
UGT vs TPA / Direct PPA — the full 9-dimension comparison
| Dimension | UGT (Utility Green Tariff) | TPA / Direct PPA (wheeling) |
|---|---|---|
| Who you contract with | The utility (MEA/PEA) — a standardized product | The generator / IPP directly (a bilateral Direct PPA) |
| Fee / price structure | An ERC-set green-tariff rate, bundled on your normal utility bill (rate subject to the current ERC period — verify) | A negotiated $/kWh plus a wheeling charge for grid use (wheeling fee set by the regulator/EGAT, subject to pilot terms — verify) |
| Green-attribute / certificate ownership | The green attribute / certificate is bundled into the UGT product | The buyer typically owns the attribute / RECs per contract — confirm in the PPA |
| Eligibility / access | Open to utility customers who subscribe (subject to UGT phase capacity / enrollment) | Requires Third-Party Access (TPA) rights — as of 2026 a limited pilot, not a fully liberalized market — verify with ERC/EGAT |
| Complexity / time-to-start | Low — subscribe through the utility, no negotiation | High — bilateral negotiation, wheeling arrangement, regulatory approvals |
| Volume / best load size | Flexible; good for small–mid green-power needs | Best economics at large loads where the negotiated price beats the bundled tariff |
| Price control / flexibility | Fixed by ERC — little room to negotiate | Negotiable — can be cheaper if negotiated well, but bears market/term risk |
| RE100 / reporting | Counts toward RE100 via the utility green product (verify scope with your framework) | Counts via owned RECs / contract — a stronger RE100 additionality story |
| Best-fit buyer | Wants speed + simplicity; smaller surplus need after rooftop | A large buyer with procurement bandwidth, big residual load, price-sensitive |
All fees / rates / eligibility above are set by ERC / EGAT / the utilities and can change — treat as qualitative guidance, not guaranteed figures. Verify current terms with official sources before deciding.
UGT2 — utility green tariff guide · Wheeling & Third-Party Access (TPA)
4-way table: Rooftop vs UGT1 vs UGT2 vs Direct PPA (TPA)
UGT comes in two versions, and there's also the rooftop route (cheapest) and Direct PPA (data-center-restricted). This table lines up all four so you can see what an ordinary factory can actually do in 2026.
| Dimension | Rooftop (on-site) | UGT1 | UGT2 | Direct PPA (TPA) |
|---|---|---|---|---|
| Who can join (2026) | Any factory with roof/space | Utility customers enrolled in UGT1 (launched 23 Jan 2025)* | C&I customers enrolling in UGT2 (MEA/PEA launched 30 Apr 2026)* | BOI data centers with ≥50 MW IT load/building only — ordinary factories not eligible* |
| Best fit | Every factory — always do this first (cheapest kWh) | Those wanting fast green power, short term, in the first phase | Large loads wanting to specify the source and a long contract | Hyperscale data centers meeting the pilot criteria |
| Rate / fee basis | Your own capex; no per-unit cost on self-generated kWh | An ERC-set green rate (UGT1 ≈ 4.21 THB/kWh — verify current period)* | An ERC-set UGT2 rate tied to the chosen source (verify current period)* | Negotiated PPA price + a wheeling charge (draft ~THB 1.07/unit — not final, pending ERC approval)* |
| Contract length | Your asset (25+ year system life) | Short (≈1 year per phase)* | Long (up to ≈10 years)* | Long, as negotiated (PPA projects often multi-year) |
| Actually available in 2026 | Yes — available now | By open phase / quota* | Yes — launched 30 Apr 2026 (subject to quota)* | Limited pilot phasing in from 2026, eligible data centers only (start date still draft)* |
| RE100 / REC eligibility | Eligible (self-generated) — strongest additionality story | Counts via the utility green product* | Counts via the utility product, with better source specificity* | Counts via owned RECs / contract — strong additionality |
| Complexity | Medium (one-time design + install) | Low — subscribe via the utility | Low–medium — subscribe + select source | High — negotiate PPA, arrange wheeling, approvals |
*UGT1/UGT2 rates, the wheeling charge (draft ~THB 1.07/unit, not finalized), eligibility and the Direct-PPA pilot start date are set by ERC/EGAT/the utilities and can change. Treat as qualitative guidance; verify current terms with official sources before deciding.
Decision tree: UGT or TPA — answer 5 questions
Answer 5 questions to see which route likely fits your factory better (guidance, not individualized advice).
Ready to find your answer in 2 minutes? Click to start 5 questions.
Still unsure? Start with the RE100 4-path overview or talk to CapSolar for free.
Which to choose — buyer profiles
Choose UGT if…
- You want green power fast, with no contract negotiation
- Your residual load (after rooftop) is small–mid
- You don't have a dedicated energy-procurement team
- A fixed ERC-set rate is acceptable as long as it's verifiable
Choose TPA / Direct PPA if…
- You have a large residual load (several MW) and are price-sensitive
- You have the team/time to negotiate and handle regulation
- You want price control and additionality / owned RECs
- You can confirm TPA eligibility in the current pilot
How CapSolar helps you plan both layers
CapSolar designs and installs factory rooftop solar, backed by 80+ MWp / 150+ projects in Thailand, 100+ clients, and 85,000+ tons of CO₂ avoided. We recommend maximizing the roof first (lowest cost), then assessing whether the remaining grid-import is best topped up with UGT or TPA / Direct PPA for your RE100 goal. Not sure where to start? Let us assess your roof and remaining grid-import for free.
About this guide
Compiled by the CapSolar team from ERC, EGAT and MEA/PEA policy frameworks and real factory-solar installation experience in Thailand. This comparison is general guidance, not individualized legal or financial advice — please verify current rates and eligibility with official sources.
Last reviewed Jun 2026 — TPA and UGT status may change per ERC announcements.
Frequently Asked Questions
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Related guides
UGT2 — utility green tariff guide
The UGT2 mechanism, enrollment, rate and terms for factories
Wheeling & Third-Party Access (TPA)
The wheeling mechanism, TPA pilot status, and Virtual PPA
Direct PPA — factory guide
The guide to negotiating power directly from a generator
What is a PPA
The basics of a long-term power purchase agreement
RE100 — 4 green-power paths
Rooftop → Direct PPA → UGT → IREC overview with a decision tree