Solar Farm Development Guide — Koh Phangan
Up to 9 MW · 2026
Solar Farm Development Guide — Koh Phangan
Up to 9 MW · 2026
Koh Phangan, Surat Thani · Up to 9 MW
Regulation · Permits · Timeline · Costs · Financial Model
Prepared by G · Bustan Energy · March 2026 · Updated 4 Sep 2026
Single 115kV submarine cable from mainland via Koh Samui. 2023: navy ship anchor damaged cable → blackouts on both islands. Peak season shortages (April-May). Grid upgrade to 230kV planned for 2028-2029.
Solar + Storage = grid stability insurance
Tourism-driven electricity demand growing 5-8%/year. Full Moon Party draws 30K+ visitors monthly. Hotels, resorts, bars = high AC consumption. Island grid at capacity during peak.
Local generation reduces submarine cable dependency
PEA average 3.86 THB/kWh (Sep–Dec 2026, ex-VAT); marginal small-business rate 4.58 (4.90 incl. VAT), TOU peak 5.96. PPA at ฿3.80 = immediate 15-20% savings vs the marginal rate.
NEPC approved 1,500 MW community solar (Oct 2025). VSPP program: up to 10 MW per site. Factory license exemption for solar. Thailand targeting 64 GW renewables by 2037.
Our 9 MW farm falls under Very Small Power Producer (VSPP) — the most accessible tier for solar development in Thailand.
| Category | Capacity | Regulator | Grid Buyer |
|---|---|---|---|
| VSPP ← Our project | ≤10 MW | ERC | PEA (Provincial) |
| SPP | 10-90 MW | ERC | EGAT |
| IPP | >90 MW | ERC/Cabinet | EGAT |
• 1,500 MW national target
• Ground-mount, max 10 MW/site
• One VSPP per grid connection point
• One
project per community
• 25-year non-firm PPA
• FiT: ฿2.25/kWh (from PEA)
• No FiT — sell directly to customer
• PPA rate: ฿3.60-3.80/kWh (15-20% below marginal PEA rate)
• No Ror. Ngor. 4 factory
license needed (2025+)
• Simpler permitting, faster timeline
• Better economics than FiT
• Our preferred model
BOI investment promotion for solar-only generation ended June 30, 2025. No 8-year CIT exemption for new solar farms. Alternative: hybrid models, or apply corporate tax deduction (150% on 5-star energy-saving equipment under Royal Decree 805/2026, valid until Dec 2028; scope for PV to be confirmed).
Foreigners (>49% foreign shares) cannot own land directly. Options:
| Structure | Pros | Cons |
|---|---|---|
| Thai majority company (51/49) | Can own land, standard approach | Need trusted Thai partners |
| Long-term lease (30yr + 30yr) | No Thai partner needed | No land ownership, renewal risk |
| BOI certificate (if eligible) | 100% foreign ownership + land | Solar-only no longer eligible |
| Bustan Energy partnership | Local entity exists, construction crew | Partnership terms needed |
Secure Chanote (Nor. Sor. 4) title deed. Verify zoning allows energy/industrial use. Agricultural land OK — note: Thailand has no dedicated agrivoltaic framework yet; conversion of agricultural land is generally restricted (check land title/zoning with LAO).
Submit ERC-specified consent form to Local Administrative Organization (อบต./เทศบาล). Community hearing may be required. One project per community.
Solar farms typically need Initial Environmental Examination (IEE), not full EIA. Covers land use, drainage, visual impact. Near Than Sadet National Park = extra scrutiny.
Apply for VSPP license from Energy Regulatory Commission. Submit: technical design, financial plan, site readiness proof, LAO consent, IEE report.
Apply to PEA for grid connection. Technical assessment of local grid capacity. One VSPP per connection point. 33kV or 22kV interconnection.
Building permit from local authority. Structural engineering approval for mounting systems. Electrical installation permit. Road access permits if needed.
Sign Power Purchase Agreement with PEA (FiT model) or directly with customers (self-consumption). 25-year PPA for FiT; flexible for private PPA.
Site preparation, foundation, mounting, panel installation, inverter/transformer, BESS, grid interconnection, testing.
PEA inspection and testing. Grid synchronization test. Commercial Operation Date (COD). Must achieve within 18 months of PPA signing.
Critical path: LAO consent + PEA grid assessment (can run in parallel with IEE). Construction starts ~month 8-10 after all permits secured.
| Component | Details |
|---|---|
| Main Supply | 115kV submarine cable from Khanom → Koh Samui → Koh Phangan |
| Total Capacity | ~174 MW (shared with Koh Samui, 4 circuits) |
| Distribution | 33kV and 22kV local distribution (PEA) |
| Substation | 115kV substation near Thongsala (9.7066°N, 99.9948°E) |
| PEA Office | Koh Phangan Branch (Thong Sala): 077-377-084 |
| Planned Upgrade | New 230kV submarine cable — 2028 (Circuit 1) / 2029 (Circuit 2) |
• Connect at 33kV to local distribution
• Step-up transformer: 0.4kV → 33kV
• Shorter distance if near
existing line
• Cost: ฿200K-500K per km
• Preferred for sites < 2km from
line
• Dedicated line to 115kV substation
• Higher capacity, more reliable
• Cost: ฿500K-1M per km
• Only
practical for Thongsala South site
• Best for full 9 MW capacity
9 MW on an island with 174 MW shared capacity is significant (~5%). PEA may require: grid stability study, frequency response equipment, mandatory storage. This actually strengthens the case for BESS — storage addresses PEA concerns AND creates additional revenue.
Calculation: 9,000 kWp × 5.5 m²/kWp ÷ 0.70 usable ratio = 70,714 m² = 44.2 rai solar area + buffer + roads + BESS pad ≈ 56-80 rai.
| Zone | Solar Farm OK? | Notes |
|---|---|---|
| Agricultural (Green) | ✅ Yes — Agrivoltaic | Up to 23-year installation. Dual use encouraged. |
| Residential/Commercial (Yellow) | ✅ Yes — with permit | 70% buildable area. LAO approval needed. |
| National Park / Forest | ❌ No | Than Sadet-Ko Pha-ngan NP covers ~70% of interior. |
| Coastal (Blue) | ⚠️ Restricted | Setback requirements. Visual impact review. |
| Type | Full Ownership? | Bankable? | Recommendation |
|---|---|---|---|
| Chanote (Nor. Sor. 4) | ✅ Yes | ✅ Yes | Required for solar farm |
| Nor. Sor. 3 Gor | ~Yes (accurate survey) | ⚠️ Some banks | Upgradeable to Chanote |
| Nor. Sor. 3 | ~Yes (less accurate) | ❌ No | Avoid — boundary disputes |
| Sor. Kor. 1 | ❌ Possession only | ❌ No | Avoid — cannot sell/mortgage |
40 rai · 0.8km to grid · Score: 9.2
Scout on Map →
25 rai · 0.3km to grid · Score: 8.9
Scout on Map →
30 rai · 1.2km to grid · Score: 8.8
Scout on Map →
DC Capacity: 9,000 kWp (9 MWp)
Panels: 16,216× JA / Jinko TOPCon 555W (or 15,517× 580W)
Panel Area: 2.28m × 1.13m = 2.58 m² each
Total Array Area: ~40,000 m²
Mounting: Ground-mount, fixed-tilt 15°
Orientation: South-facing (0° azimuth)
Row Spacing: 5-6m (no inter-row shading)
Inverters: Huawei SUN2000-185KTL-H3 × 48
AC Capacity: 8,880 kW (DC:AC = 1.01:1)
String Design: 24 panels per string
Combiner Boxes: 48× (one per inverter)
Transformer: 10 MVA step-up (0.4kV → 33kV)
Metering: PEA-approved bi-directional
Annual Production: ~12,150 MWh
Capacity Factor: ~15.4% (tropical, no tracking)
Specific Yield: 1,350 kWh/kWp/yr
PR (Performance Ratio): ~80%
Degradation: 0.4-0.5%/yr (Tier-1 TOPCon warranty)
25-year output: ~280,000 MWh total
Site Area: 80 rai (128,000 m²)
Fencing: 2.4m chain-link, 1.6 km perimeter
Access Roads: 4m wide gravel/concrete
Drainage: Retention pond + swales
Foundation: Driven steel piles (no concrete)
Security: CCTV, 24/7 monitoring
On an island with a vulnerable submarine cable, storage isn't optional — it's a competitive advantage.
Capacity: 4,500 kWh (50% solar:storage)
Power: 2,250 kW (2-hour discharge)
Technology: Huawei LUNA2000-215kWh × 21
Chemistry: LFP (Lithium Iron Phosphate)
Cycles: 6,000+ (15-year warranty)
Round-trip Efficiency: 95%
Footprint: ~300 m² (containerized)
1. Peak Shaving: Charge at midday (low demand), discharge at evening peak. Value:
~฿2.5M/yr
2. Arbitrage: Buy low (฿3/kWh off-peak) sell high (฿7/kWh peak). Value: ~฿3.3M/yr
3. Grid Stability: Frequency regulation for PEA. Value: ~฿1.0M/yr
4. Backup Power: Premium service during cable outages. Value: negotiable
Total BESS Revenue: ~฿6.8M/yr
9 MW solar on a 174 MW island grid = 5% of capacity. Without storage, PEA may reject due to intermittency concerns. With BESS, we offer grid stability, peak shaving, and backup — making PEA an ally, not a gatekeeper.
| Item | Unit Cost | Total (฿) | % of Total |
|---|---|---|---|
| Solar Panels (16,216× JA/Jinko 555W TOPCon) | ฿1,750/panel (6.5-7.5 ฿/W landed) | 28,378,000 | 15% |
| Inverters (48× Huawei 185kW) | ฿245,000/unit | 11,760,000 | 6% |
| Mounting Structure (ground-mount) | ฿1,200/kWp | 10,800,000 | 4% |
| Electrical (cables, combiner, switchgear) | ฿1,500/kWp | 13,500,000 | 5% |
| Transformer (10 MVA, 0.4→33kV) | lump sum | 8,000,000 | 3% |
| BESS (4,500 kWh Huawei LUNA) | ฿8,000/kWh (utility-scale LFP, installed) | 36,000,000 | 19% |
| Civil Works (fencing, roads, drainage) | lump sum | 12,000,000 | 4% |
| Grid Connection (33kV, ~2km) | ฿300K/km | 600,000 | 0.2% |
| Land (80 rai @ ฿800K) | ฿800K/rai | 64,000,000 | 35% |
| Total CapEx | ฿185,038,000 | 100% | |
| Per MW (solar only) | ~฿9.4M/MW (excl. land & BESS) | ||
| Per MW (all-in) | ~฿20.6M/MW (~$620K/MW) | ||
| Item | Annual Cost (฿) |
|---|---|
| O&M (1.5% of solar CapEx) | 1,275,000 |
| BESS maintenance | 360,000 |
| Insurance | 1,500,000 |
| Land lease / property tax | 500,000 |
| Security & monitoring | 600,000 |
| Administrative | 300,000 |
| Total Annual OpEx | ฿4,535,000 |
Rate: ฿2.25/kWh (fixed)
Annual: ฿27.3M
25-year: ฿683M
Buyer: PEA
Risk: Low (guaranteed)
Lower rate but zero off-take risk
Rate: ฿3.80/kWh (+1.5%/yr)
Year 1: ฿54.7M
25-year: ฿1.75B
Buyer: Hotels, resorts, businesses
Risk: Medium (customer credit)
2x the FiT revenue — our target model
Rate: Mixed
Split: 5 MW PPA + 4 MW FiT
Year 1: ฿41.4M
25-year: ฿1.24B
Risk: Low-Medium
Balanced approach
| Stream | Annual (฿) | 25-year (฿) |
|---|---|---|
| Peak Shaving | 2,500,000 | 62,500,000 |
| Arbitrage | 3,300,000 | 82,500,000 |
| Grid Services | 1,000,000 | 25,000,000 |
| Total BESS Revenue | 6,800,000 | 170,000,000 |
| Period | Solar Rev | BESS Rev | OpEx | Net CF | Cumulative |
|---|---|---|---|---|---|
| Year 1 | ฿54.7M | ฿6.8M | -฿6.0M | ฿55.5M | -฿236.5M |
| Year 3 | ฿56.9M | ฿6.8M | -฿6.2M | ฿57.5M | -฿123.3M |
| Year 5 | ฿59.2M | ฿6.8M | -฿6.4M | ฿59.6M | +฿5.6M ✅ |
| Year 10 | ฿65.3M | ฿6.8M | -฿7.0M | ฿65.1M | +฿317M |
| Year 15 | ฿72.1M | ฿3.4M* | -฿7.7M | ฿67.8M | +฿649M |
| Year 20 | ฿79.6M | ฿3.4M* | -฿8.4M | ฿74.6M | +฿1.01B |
* BESS revenue halved after year 12 (degradation). Solar degradation 0.4%/yr. OpEx escalation 2%/yr. PPA escalation 2%/yr.
฿292M investment → ฿1.01B net return over 20 years. 3.5x return on investment. Payback in under 5 years. Monthly cash flow from month 1.
| Risk | Severity | Mitigation |
|---|---|---|
| PEA rejects grid connection | High | Include BESS for grid stability. Engage PEA early. Start with 5 MW, scale to 9. |
| Land title issues | Medium | Only pursue Chanote title. Due diligence with lawyer. Title insurance. |
| Community opposition | Medium | Agrivoltaic design (farming under panels). Community benefit sharing. Jobs. |
| Typhoon/storm damage | Medium | Engineering for 150 km/h winds. Insurance. Concrete foundations if needed. |
| Customer credit risk (PPA) | Medium | Target hotels/resorts with stable revenue. Bank guarantee. Multiple offtakers. |
| Foreign ownership restriction | Medium | Bustan Energy partnership. Proper legal structure. Registered lease backup. |
| Submarine cable upgrade (2028) | Low | More capacity = more potential customers. Our storage becomes less critical but solar remains valuable. |
| Regulatory change | Low | Thailand consistently expanding solar targets. Lock in PPA early. |
| Equipment supply chain | Low | JA/Jinko + Huawei = global supply. Thailand has local PV manufacturing (10 GW/yr). |
| Month | Phase | Key Activities |
|---|---|---|
| 1-2 | Due Diligence | Land shortlisting, title verification, PEA pre-consultation, legal structure setup |
| 3-4 | Land & Community | Land acquisition/lease, LAO consent application, community engagement |
| 3-5 | Environmental | IEE preparation, environmental review, drainage design |
| 4-6 | Licensing | ERC VSPP application, PEA grid connection application |
| 5-7 | Engineering | Detailed design, structural engineering, electrical design, BESS sizing |
| 6-8 | Procurement | RFQ to suppliers, panel/inverter/BESS orders, EPC contractor selection |
| 7-8 | PPA Signing | Execute PPA with PEA/customers, secure financing |
| 8-9 | Site Prep | Clearing, grading, access road, fencing, foundation piles |
| 9-13 | Construction | Mounting, panels, inverters, BESS, transformer, grid interconnect |
| 14-15 | Testing | String testing, inverter commissioning, BESS testing, grid sync test |
| 16 | PEA Inspection | Final inspection, metering verification, safety certification |
| 17-18 | COD ✅ | Commercial Operation Date, revenue starts flowing |
Visit PEA Koh Phangan office (077-377072). Ask: available grid capacity at 33kV, process for 9 MW VSPP, BESS requirements, estimated timeline.
Contact: Islanders Properties, KPN Properties, Conrad Properties. Visit top 3 candidate sites. Verify Chanote titles. Get price quotes for 50-80 rai.
Define partnership terms. Set up Thai entity (if needed). Clarify land ownership structure. Engage Surat Thani lawyer for due diligence.
Meet local อบต./เทศบาล. Present project benefits: jobs, community power, tax revenue. Begin consent process.
Send RFQs to: Solaris Green Energy, BayWa r.e., VST ECS, High Solar, Solar-Thailand. Request: 9 MW ground-mount + 4.5 MWh BESS pricing.
PEA Koh Phangan: 077-377072, 077-377073
Bustan Energy: 094 669 2011 (partner)
Islanders Properties: islanders-properties.com
KPN Properties: kpnproperties.com
ERC: erc.or.th
Bustan Energy (us): k@kanielt.com
Bustan Energy · Bustan Energy Farm Development Guide · March 2026 · Confidential
Data sources: NEPC, ERC, PEA, OpenStreetMap, Thai property listings, IRENA, industry reports
Interactive Scout Tool: index.bustan-energy.com/solar-farm-scout.html