Compare Solar PPA and EPC across 12 dimensions — investment, ROI, risk, BOI, cash flow, ownership — with a 2-minute decision tree to guide your choice.
EPC (Engineering, Procurement, Construction) means the factory invests 25-35M THB/MWp upfront, owns the system 100%, and recovers costs in 4-7 years. PPA (Power Purchase Agreement) means a provider invests instead -- the factory pays only for actual kWh produced, at 10-30% below grid rate, with zero upfront cost.
| Dimension | EPC | PPA |
|---|---|---|
| Investment | 25-35M THB/MWp upfront | Zero upfront |
| Ownership | Factory owns 100% | Provider owns |
| Payback | 4-7 years | Immediate savings |
| Bill savings | 40-60% | 10-30% |
| Risk | Factory bears all | Provider bears |
| BOI eligible | Yes (Section 30) | No |
EPC (Engineering, Procurement, Construction) is a solar procurement model where the factory funds the entire system — design, equipment, construction — at 25-35M THB/MWp. The customer owns 100% of the system, recovers cost in 4-7 years, and saves 40-60% on electricity for the 25-year lifetime (versus PPA, where the provider funds the system and the customer pays only for electricity produced).
| Aspect | EPC | PPA |
|---|---|---|
| Contract type | One-time turnkey build | 15-25 year power purchase agreement |
| Who invests | Factory itself (25-35M THB/MWp) | Provider (zero customer capex) |
| System ownership | Factory owns 100% | Provider owns |
| Who bears risk | Factory (O&M, output) | Provider (output guaranteed) |
The key difference: EPC means you invest upfront (25-35M THB/MWp) and own 100% of the system — 4-7 year payback, then 100% electricity savings for 25 years. PPA means zero investment — the provider installs for free and you pay only for electricity generated at 10-30% below grid rates. In short: EPC = pay once, maximum savings; PPA = pay nothing upfront, save immediately.
PPA (Power Purchase Agreement) is a contract where the solar provider funds the entire installation; the customer pays only for electricity at 10-30% below grid rates. EPC (Engineering, Procurement, Construction) is when the customer funds and owns the system outright — turnkey delivery, 4-7 year payback, and 100% savings thereafter.
Under PPA, the provider (e.g., CapSolar) funds the entire installation and bills the customer for each kWh the system actually produces. Rates typically fall between 2.50-3.20 THB/kWh (25-40% below PEA/MEA TOU peak) with a 1-3% annual escalator. Monthly bills are measured via a dedicated export meter separate from the grid meter. Customers typically have a buyout option between years 7-10, depending on contract structure. Before signing, review the PPA contract clauses to check before signing — including the escalator rate and buyout terms.
Under EPC, the customer pays a turnkey CAPEX of roughly 25-40M THB per MWp (varies by roof structure, panel brand, MDB distance, BOI status). Payment is usually structured as milestones: 30% upfront + 40% on delivery + 30% at COD. It covers engineering design, procurement (panels, inverters, mounting, cabling, monitoring), installation, ERC/PEA/MEA permitting, and grid interconnection. Post-handover O&M is not included — most customers sign a separate O&M contract at 1,500-3,000 THB/kWp/year. For the complete Thai solar regulatory framework & licensing, see our regulatory overview.
Note: Figures are 2026 CapSolar estimates (actual size, load profile, PPA rate, and Ft may vary). Run your own scenario at the PPA vs Self-investment Calculator. Before comparing numbers, settle on the right system size for your factory load first.
The biggest difference between PPA and EPC isn't just the money — it's who bears risk across each dimension. The table below summarizes 8 major risk types and the responsible party under each model.
| Risk Type | PPA — Who Bears | EPC — Who Bears |
|---|---|---|
| Performance (underproduction) | Provider | Customer |
| Equipment failure (panel/inverter) | Provider | Customer (under warranty or post-warranty) |
| Tariff rise (PEA/MEA increase) | Customer benefits (PPA locked lower) | Customer benefits (100% savings) |
| Tariff drop (PEA/MEA decrease) | Customer at risk (PPA rate locked) | Customer at risk (payback extends) |
| BOI / tax incentive | Provider claims (customer cannot use CIT/import duty) | Customer claims directly (CIT exemption + duty-free imports) |
| Property (roof leaks, damage) | Provider (performance + insurance included) | Customer (must buy insurance separately) |
| Tech obsolescence | Provider (usually refreshes inverter mid-contract) | Customer (inverter lasts 10-12 yrs, self-funded replacement) |
| Counterparty (provider insolvency) | Customer at risk (review financial stability + step-in rights) | N/A after handover (only warranty claims remain) |
PPA expenses are booked as opex (electricity cost), not as a balance-sheet asset. There's no depreciation to compute and no impact on debt capacity — suitable for companies that want to preserve a clean balance sheet for banking covenants or ROE metrics. Accounting is straightforward: monthly electricity fee × 25 years, as paid. No asset componentization required.
EPC costs are capitalized as PP&E and depreciated over 10-20 years (IAS 16 / Thai GAAP — most use 20-year straight-line). BOI Section 30/31 offers 3-8 year CIT exemption + import duty exemption on panels/inverters, reducing effective CAPEX by 10-15%. If loan-financed, interest is booked separately as finance cost. Check BOI eligibility with our free tool.
Under IFRS 16 (fully effective in Thailand since 2020), PPA contracts with "controlled use of identified assets" may be classified as a lease, requiring right-of-use asset + lease liability capitalization. Most CapSolar on-site rooftop PPAs are structured as service contracts (pay-for-output), which is not a lease under IFRS 16 §9 — but your auditor should review the contract before signing.
The 3 hypothetical cases below reflect the customer archetypes CapSolar commonly sees in Thailand — not any specific client. Figures are approximations.
Auto-parts factory, 2,000 sqm rooftop, 200K THB/month electricity bill (~2.4M/year). The owner doesn't want to deploy cash because they're expanding production lines. Recommended system size: 150 kWp. **Recommendation: PPA** — zero investment, immediate ~25% savings = 600K/year × 15 years = 9M THB without impacting working capital.
Electronics group with 3 factories in EEC, already holds BOI Section 30 (0% CIT for 8 years). Total electricity bill 5M/month = 60M/year. The finance team has CAPEX budget and wants maximum ROI. Combined system size: 3 MWp. **Recommendation: EPC** — CAPEX ~90M THB (~75M net of BOI), payback ~4 years, then 100% savings = 20M/year × 21 remaining years = 420M THB. Plus duty-free imports on panels/inverters.
Retail mall leases the building from a landlord with 10 years remaining on the lease. Electricity bill 1M/month. The tenant cannot deploy CAPEX because they don't own the building. System size: 500 kWp. **Recommendation: tri-party PPA** — landlord co-signs with tenant and CapSolar. Contract term matches the lease (10 years) + a clause to transfer the PPA to the new tenant or landlord if the current tenant moves out. Savings ~250K/month = 30M over 10 years.
See CapSolar's real project track record on the projects page.
| Dimension | PPA | EPC |
|---|---|---|
| Upfront investment | 0 THB | 25-40M THB/MWp |
| System ownership | CapSolar (15-25 yrs) | Customer 100% |
| O&M responsibility | Included (CapSolar) | Customer (or separate O&M contract) |
| Electricity savings | 10-30% from day 1 | 100% after payback |
| Payback period | N/A (no investment) | 4-7 years |
| Contract term | 15-25 years | Panels 25 yrs / inverter 10-12 yrs |
| Best fit for | Cutting opex, fast ESG, no-capex | Max long-term ROI, CAPEX budget, BOI |
| Performance risk holder | CapSolar | Customer |
| Balance-sheet impact | None (opex) | Recorded as asset + depreciation |
| BOI / tax incentive | Provider claims | Customer claims direct (CIT + import duty) |
| End-of-contract options | Buy residual / renew / decommission | Already owned |
| Time-to-savings | Day 1 at COD (10-30% immediately) | Day 1, but 100% savings only after 4-7 year payback |
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This article was written by CapSolar's engineering and financial advisory team and reviewed by our Chief Engineer and Finance Director. Our team develops and operates 80+ MWp across 150+ EPC and PPA projects in Thailand, covering PPA contract negotiation, BOI privilege usage, ERC/PEA/MEA compliance, and long-term O&M.
Written by: Frank Lee (Founder, CapSolar) · Reviewed by: Chief Engineer, CapSolar · Published: April 23, 2026 · Last updated: April 23, 2026
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