Thailand's 200,000 THB solar tax deduction — the 2026 guide for expats

Published in the Royal Gazette in March 2026, Royal Decree No. 805 created a personal income tax deduction of up to 200,000 THB (including VAT) for the cost of installing rooftop solar on your home. It is a deduction, not a rebate: the amount comes off your taxable income, and the cash you save equals the deduction multiplied by your marginal tax rate. It is claimed once, in the tax year the system is installed and grid-connected.

The intent is clearly residential: one system per household, sized for a home rather than a business. For most Phuket houses and villas that is exactly the 5–10 kWp range we install week in, week out — so for many of our customers the deduction covers a large share of the system price. (For current system prices in THB, see our 2026 solar cost guide for Phuket.)

Take a 10 kW on-grid system — a typical size for a Phuket pool villa, priced at roughly 350,000–500,000 THB before VAT. The system comfortably exceeds the cap, so you deduct the full 200,000 THB from your taxable income. Because it is a deduction, the cash back depends on your marginal Thai personal income tax rate:

So a taxpayer in the 25% band effectively gets 50,000 THB off a 10 kW system — on top of the electricity savings themselves. In Phuket's sun, each kWp produces around 150 units a month; if you use that power yourself instead of buying it at ~4.3 THB per unit, 1 kWp is worth roughly 600–650 THB a month. The deduction simply shortens the typical 4–7 year payback further. If your system costs less than 200,000 THB including VAT — a 3 kW system, for example — you deduct the actual amount paid. Run your own numbers with our savings calculator.

The deduction arrived in the same year as a new round of the household solar buy-back: PEA opened applications on 1 July 2026, paying 2.20 THB per unit of exported surplus under a 10-year purchase agreement. Both incentives apply to grid-connected rooftop systems, so a single installation can claim the tax deduction and earn the buy-back.

One detail to plan around: the buy-back caps export capacity at 5 kW AC per meter, while the tax deduction allows systems up to 10 kWp. That mismatch is fine — a 10 kWp system still claims the full deduction; it just cannot register more than 5 kW AC for export. And remember the arithmetic that drives all our designs: self-consumed power saves you ~4.3 THB per unit while exported power earns 2.20 THB, so size for your own daytime use first and treat the buy-back as a bonus. Full details, application steps and honest caveats are in our guide to selling solar power back to PEA.

1. 1 · E-tax invoice from a VAT-registered installer
   The core document. Issued in your name — the same name as on the electricity meter. We are VAT-registered and issue e-tax invoices as standard.
2. 2 · Electricity meter registration in your name
   Check your PEA bill before ordering. If the meter is under a previous owner, a landlord or a company, sort the transfer first — it is far easier before installation than after.
3. 3 · PEA grid-connection approval
   Evidence the system is on-grid and formally connected. We prepare and submit the PEA paperwork for every install, so this lands in your file automatically.
4. 4 · Contract and proof of payment
   Keep the installation contract and payment records matching the invoice amount, dated within the 3 March 2026 – 31 December 2028 window.
5. 5 · Your Thai tax filing
   Claim in the return for the tax year the system is installed and grid-connected. If you are new to Thai tax filing as an expat, have your accountant confirm your residency status for the year.