The 40-Second Answer
From early 2024 to Q2 2026, Tier-1 TOPCon module spot prices fell from roughly USD 0.18/W to USD 0.085-0.10/W (about 50%, as reported by pv-magazine markets desk). Thai factory installed cost dropped from ~28 THB/Wp in 2024 to 14-25 THB/Wp in 2026, compressing payback ~30%. The window may close as Chinese manufacturers rebalance capacity.
Tier-1 TOPCon -50% / Thai EPC -30% / payback -30%
This is not a seasonal dip; it is a structural reset. A Chinese cell-capacity overhang of roughly 1.2 TW against ~600 GW of global demand (per 2024 market commentary from BloombergNEF and pv-magazine) forced Tier-1 manufacturers to sell below cash cost. The result: the CapEx per kWp a Thai factory pays today is the lowest in a decade — and it is unlikely to stay here through 2027.
The 4-Quarter Collapse — See It in the Data
The table below summarizes the level-shift in Tier-1 TOPCon spot prices and Thai factory EPC turnkey, as reported by BloombergNEF, the pv-magazine markets desk, and IEA Renewables 2024 (figures are approximate per reporting, not quotations).
| Period | Tier-1 TOPCon spot (USD/W) | Thai EPC turnkey (THB/Wp) | Implication |
|---|---|---|---|
| Q1 2023 | ~0.20 | ~30 | Pre-oversupply baseline |
| Q1 2024 | ~0.18 | ~28 | Polysilicon glut begins |
| Q4 2024 | ~0.10 | ~22 | Tier-1 cash-cost floor |
| Q2 2026 | 0.085-0.10 | 14-25 (by system size) | Current — payback compressed to ~5.5 yr (was ~8 yr) |
Figures are approximate per pv-magazine markets desk and BloombergNEF reporting. Thai EPC turnkey references the CapSolar 2026 Thai market pricing guide (see the solar panel price 2026 page for size-by-size pricing) and is not a per-project quotation. see size-by-size pricing.
Why Modules Got Cheaper — 3 Forces
The price drop is not coincidence — it is three forces converging in 2024, per BloombergNEF, the pv-magazine markets desk, IEA Renewables 2024, and ITRPV 2024 commentary (paraphrased as narrative, not official figures).
Polysilicon glut 2023-2024
Polysilicon fell from above USD 30/kg in early 2023 to roughly USD 5-7/kg in 2025 per BloombergNEF reporting, repricing the entire cell + module cost stack.
Chinese cell capacity ~1.2 TW vs global demand ~600 GW
Chinese cell capacity exceeded global demand by roughly 2x (per 2024 BloombergNEF and pv-magazine markets-desk commentary). With cell lines needing to run to cover depreciation and interest, the result was a price war pushing wholesale below cash cost.
TOPCon enters the steep learning curve
The PERC -> n-type TOPCon transition lifted cell efficiency to 22-23% and accelerated cost-per-watt declines, as projected by ITRPV 2024 and reported by the pv-magazine markets desk.
Thai Factory Translation — The CFO Math
Chinese export wholesale prices are very low, but how much reaches the actual Thai installed cost? About 60-75%, because inverters, structure, BOS, labor, and Thai import duties move less than modules. Still, when stacked up, the impact on payback for a 1 MWp factory system in Greater Bangkok / Northeast Thailand is material.
Assumes ~4.2 THB/kWh average TOU, 80% self-consumption, no BOI incentives stacked. Use our ROI calculator with your actual bill for site-specific numbers. open the ROI calculator.
Why the Window May Close — 4 Catalysts
Tier-1 prices at USD 0.085/W are unlikely to last long because many manufacturers are selling below cash cost. Per pv-magazine markets desk and ITRPV 2024 forecasts, wholesale could rebound 10-20% in 2027 — and four catalysts could shut this window.
China rationalization
Beijing is starting to push loss-making producers to consolidate or curtail capacity, which would gradually wind down the overhang.
US Section 58 / trade measures
Anti-dumping investigations into Southeast-Asia-transhipped cells raise costs for producers still selling into the US and may ripple back into Asian export pricing.
Hormuz-driven FX volatility
The Hormuz blockade (Feb 2026) lifts LNG and FX risk for the THB — every 1 THB/USD weakening shifts CapEx for a 1 MWp system by 500-800K THB.
TOPCon -> HJT / BC migration
Next-gen technologies (HJT, BC) will take share and raise average pricing as TOPCon lines reconfigure — per ITRPV 2024 outlook.
What CapSolar Sees in the Market — 80+ MWp / 150+ Projects
At CapSolar we have designed and installed factory solar totaling 80+ MWp across 150+ commercial deployments spanning 100+ industrial clients — and 2026 wholesale pricing flows directly into every quote we issue. Most customers land in a turnkey EPC band of 14-25 THB/Wp (by size) with payback of 5-7 years before BOI incentives stack.
80+ MWp installed · 150+ projects · 100+ clients · 85,000+ tons CO2 avoided
Market prices we observe span 14-25 THB/Wp depending on system size and brand selection. See the size-by-size pricing in our 2026 factory solar price guide and pressure-test any quote with the 20-point procurement checklist. 2026 factory solar price guide / procurement checklist.
What to Do This Quarter — 3 CFO Steps
This CapEx window is not open forever — waiting 6 months for an extra 1 THB/Wp module decline is typically not worth 6 months of unhedged TOU bills (~1.5M THB on a 1 MWp factory). Three CFO steps:
Get 3 turnkey EPC quotes this month
Thai installation supply is healthy — request identical system size, module + inverter spec, and warranty scope across vendors so price comparison is true like-for-like.
Lock BOI 2026
BOI Section 8.1 / Royal Decree 805 accelerated tax depreciation for solar pairs powerfully with today's low CapEx — stacking is what delivers maximum IRR.
Re-run the ROI calculator with current pricing
If payback comes out at 6 years or less, commit. Waiting introduces FX and policy tail-risk that easily wipes out the further 1 THB/Wp decline.
Capture the 2026 Price Window — Get a Free Quote
CapSolar's team assesses your roof, electricity bill, TOU profile, and quotes turnkey EPC at real 2026 market pricing.