Is rooftop solar net-metering worth it for a Thai factory in 2026? Worked payback example (4-7 years), system-size limits, the MEA/PEA license timeline, and net-metering vs net-billing explained — with a free ROI quote.
Why Solar Rooftop is Compelling in Thailand
Industrial electricity in Thailand averages ฿3.8-4.2/kWh (Type 4 demand charge) and commercial buildings ฿4.5-4.8/kWh — 30-50% higher than ASEAN average.
Solar panel pricing (2024-2026): ฿14-22/Wp installed — payback 4-7 years compared to:
- Bank deposit: 1.5-2.5% IRR
- Mutual funds: 4-7% IRR
- Solar self-consumption: 15-25% IRR
But every project requires MEA/PEA + DOEB + ERC permits — 2024 rules changed from 1:1 Net-Metering to Net-Billing with lower export rate.
Net-Metering vs Net-Billing — Critical Distinction
graph LR
A[Net-Metering 1:1] --> A1[Export 100 kWh = Credit 100 kWh
same rate]
A --> A2[Used in early Thai pilot 2013-2018
High value, utility not profitable]
B[Net-Billing] --> B1[Export 100 kWh × ฿2.2/kWh = ฿220
Import 100 kWh × ฿4.18 = ฿418]
B --> B2[Used by MEA/PEA 2020+
Self-consumption preferred]Math under Net-Billing:
- 100 kWp installed for factory consuming ~500 kWh/day (peak hours)
- Production ~450 kWh/day (annual ~150,000 kWh)
- Self-consume ~380 kWh (84%) × ฿4.18 = ฿1,588/day savings
- Export ~70 kWh (16%) × ฿2.2 = ฿154/day income
- Total: ฿1,742/day = ฿52,260/month
- System cost ~฿1.5-1.7M
- Payback: 2.7-3.3 years (high self-consumption) or 4-5 years (high export)
Key insight: Self-consumption % matters most — design system to peak production matching peak load.
MEA vs PEA Coverage
| Provider | Coverage | Best For |
|---|---|---|
| MEA (Metropolitan EA) | Bangkok, Nonthaburi, Samut Prakan | Urban factories, BKK commercial |
| PEA (Provincial EA) | 74 other provinces | Provincial factories, industrial estates |
Both use same Tariff structure (Type 1-5) + similar Net-Billing rules.
License Process — Standard (200-1,000 kWp)
flowchart TD
Start[Install Decision] --> Survey[1. Site Survey + Load Analysis]
Survey --> Design[2. Design + Single-Line Diagram]
Design --> Apply[3. MEA/PEA Application]
Apply --> Review{MEA/PEA Review
30-45 days}
Review -->|Approved| DOEB[4. DOEB Permit if > 200 kWp]
Review -->|Reject| Revise[Revise + re-apply]
DOEB --> Install[5. Install — 4-8 weeks]
Install --> Test[6. Commission per IEC 61727]
Test --> COD[7. Commercial Operation Date]Required Documents (5 sets per MEA/PEA 2024)
- Application Form (from MEA/PEA website)
- Single-Line Diagram — drawn by Licensed Engineer (Phakee Wisawakorn)
- Technical Specifications:
- PV module spec (Tier 1 preferred)
- Inverter spec with IEC 61727 / IEEE 1547 test report
- Cable + breaker spec
- DBD Certificate (company registration)
- Land Ownership Proof or rental contract ≥5 years
Timeline Reality (2024 data)
| Project Size | Standard Timeline |
|---|---|
| <200 kWp (Simple) | 2-4 weeks |
| 200-1,000 kWp (Standard) | 1-3 months |
| 1,000-5,000 kWp (ERC) | 3-6 months |
| >5,000 kWp (ERC + EIA) | 6-12 months |
ROI Calculation Example
Scenario: Plastic factory, 5,000 m², Nonthaburi
Current bill profile:
- Monthly consumption: 80,000 kWh
- Average rate (Type 4): ฿4.05/kWh
- Monthly bill: ฿324,000
Solar system design:
- Size: 350 kWp on rooftop (capacity factor ~16% in Thailand)
- Annual production: 490,000 kWh
- Daily average: ~1,340 kWh
Self-consumption analysis:
- Plant operates 7am-7pm
- Solar peak 10am-3pm matches well
- Estimated self-consumption: 85%
Annual savings:
- Self-consume: 416,500 kWh × ฿4.05 = ฿1,686,825
- Export: 73,500 kWh × ฿2.2 = ฿161,700
- Total: ฿1,848,525/year
Investment: 350 kWp × ฿18,000/kWp = ฿6,300,000
Payback: ฿6.3M / ฿1.85M = 3.4 years
25-year cumulative net: ~฿40.7M (assuming 0.5% annual degradation, no tariff inflation)
IRR: ~22% over 25 years
Common Mistakes
1. Oversize system → low self-consumption → high export at low rate
Wrong: 500 kWp for factory peaking at 200 kW Fix: Match system size to peak daytime load × 0.85
2. Ignoring demand charge
Wrong: Only considering energy charge (฿4.05/kWh), missing demand charge (฿132-350/kW) Fix: Solar + Battery for peak shaving reduces both
3. Inverter without IEC 61727 cert
Wrong: Cheap inverter without certification Fix: Use Tier 1 brands — Sungrow, Huawei, SMA, Fronius, GoodWe
4. Skipping roof load capacity check
Wrong: Installing 12-15 kg/m² panels on weak roof Fix: Civil PE calculate roof load + sign off
5. No shading analysis
Wrong: Installing under shade of building/tree/HVAC chimney Fix: PVsyst or Helioscope simulation + drone survey
Saha Solar Service Tiers
Tier 1: Consultation (฿20-50K)
- Site survey + drone roof image
- 12-month load profile analysis
- Preliminary design (3 options) + 25-yr ROI calc
Tier 2: Design + Permit (฿100-300K)
- Single-line diagram + Licensed Engineer stamp
- MEA/PEA + DOEB submission package
- Project timeline
Tier 3: Turnkey EPC (฿14-18K/kWp)
- Tier 1 procurement + installation + commissioning
- 25-year monitoring service available
Tier 4: Long-term O&M (฿200-400/kWp/year)
- Quarterly cleaning + inspection
- Annual IV-curve test per IEC 61853
- Warranty + insurance support
BOI / Tax Incentives
| Incentive | Benefit | Eligibility |
|---|---|---|
| BOI Section 8 Renewable Energy | 200% tax deduction | >1 MWp + Thai content >40% |
| Section 73 Environmental | 8-year tax holiday | EIA-approved projects |
| Accelerated depreciation | 100% year 1 | Energy efficiency assets |
| EXIM Bank Green Loan | 3-4% interest (vs commercial 5-6%) | Verified renewable project |
Summary
- Net-Billing (not Net-Metering) is current MEA/PEA scheme 2024
- Self-consumption % is the most important variable
- License process: Simple (2-4 wk) → Standard (1-3 mo) → ERC (3-6 mo)
- Realistic payback: 3.5-6 years industrial · IRR 15-25% over 25 yr
- 5 documents required: Application + Single-line + Tech spec + DBD + Land proof
- Common mistakes: oversize, ignore demand charge, cheap inverter, no shading analysis
Saha provides design + permit + install + commission packages — contact 02-096-2118 or visit /solar for free TCO calculator.
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Frequently Asked Questions
1Is Net-Metering available for all meter types in Thailand?
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2Net-Metering vs Net-Billing — what's the difference?
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3Maximum PV system size?
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4Realistic payback period in Thailand?
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5Is battery storage needed?
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