Is solar worth it in Thailand?
— the honest 2026 math
We install solar for a living, so you'd expect us to say yes. Instead, here's the payback worked line by line for a real Phuket villa scenario — plus the four cases where we'd tell you not to install. Judge the numbers yourself.
For most Phuket homes with meaningful daytime electricity use, yes: a rooftop system pays for itself in 4–7 years, then produces near-free power for the rest of its 25–30 year panel life. Example: a 10 kW system at 350,000–500,000 THB saves up to ~6,400 THB a month at ~4.3 THB per unit. Solar is not worth it if your roof is heavily shaded, you use little power in daylight and won't add a battery, you're moving within ~4 years, or you rent and the owner won't consent.
Payback for a Phuket pool villa, line by line
A 3-bed pool villa in Phuket commonly pays 7,000–10,000+ THB a month for electricity — aircon alone is typically ~60–65% of that. Here's the full calculation for a 9,000 THB/month villa.
| Step | Calculation | Result |
|---|---|---|
| 1 · Current usage | 9,000 THB ÷ ~4.3 THB/unit | ~2,100 units/month |
| 2 · System sized for daytime load | 10 kW × ~150 units per kWp | ~1,500 units/month produced |
| 3 · Value if self-consumed | 1,500 units × ~4.3 THB | up to ~6,400 THB/month saved |
| 4 · Annual saving | ~6,400 THB × 12 | ~77,000 THB/year |
| 5 · System cost (10 kW on-grid, before VAT) | Phuket 2026 range | 350,000–500,000 THB |
| 6 · Simple payback | Cost ÷ annual saving | ~4.5–6.5 years |
The honest assumption to check is step 3: the saving is only real for units you use as they're produced. Pool villas are the best case — the pool pump runs 6–8 daytime hours and afternoon aircon lines up with peak output. A home that's empty all day captures far less, which is why we review your actual bills at the free site survey before quoting. On top of this, individuals installing up to 10 kWp in 2026–2028 can deduct up to 200,000 THB from taxable income under Royal Decree No. 805 — worth up to a year or more off the payback; the full conditions are in our tax deduction guide. Current system prices are broken down in Solar panel cost in Phuket (2026).
Why we calculate at 4.3 THB per unit
Thailand's headline residential tariff was trimmed to just under 4 THB per unit in late 2025 — and that's the number sceptics quote. But the residential tariff is progressive: high-usage homes (over ~400 units a month, which is every villa we survey) pay roughly 4.2–4.4 THB for each additional unit. Since solar offsets those top-tier marginal units first, ~4.3 THB is the honest rate for the power your roof replaces — it matches the real Phuket bills we review every week. One more piece of context: exported surplus earns only 2.20 THB per unit under the PEA buy-back scheme that opened 1 July 2026 (details in our PEA buy-back guide), so self-consumption is worth roughly twice as much as selling. Size for your own use first; the buy-back is a bonus.
When solar is NOT worth it
About one survey in ten, we tell the owner to wait or to skip solar entirely. These are the four situations where the math genuinely doesn't work.
What happens after payback
Payback is the wrong place to stop the calculation, because the system doesn't stop at year 5. Tier-one panels carry performance warranties of ~25 years, last 25–30 years in practice, and degrade at less than 1% per year — a panel still produces the large majority of its original output decades in. Budget honestly for one item: the inverter realistically lasts 10–15 years, so expect one replacement over the system's life. In our villa example, the years after payback deliver on the order of 70,000+ THB of avoided electricity annually — roughly 1.4–1.9 million THB over the remaining panel life even before any tariff increases. In coastal Phuket the caveat is hardware: we install corrosion-resistant mounting and coastal-rated components as standard (see our services), because cheap racking rusts long before LONGi panels wear out. Want to run your own numbers first? Try the savings calculator, or read how pool villas and hybrid battery systems change the picture.
Worth-it questions, answered straight
How long does solar take to pay for itself in Thailand?
Typically 4–7 years in Phuket, faster for homes with high daytime consumption. A 10 kW system costing 350,000–500,000 THB produces about 1,500 units a month, worth roughly 6,400 THB at the ~4.3 THB per unit that high-usage homes pay. After payback, the panels keep producing for 25–30 years with degradation under 1% per year.
Is solar worth it if I'm away from Thailand half the year?
It can be, but the math changes. An empty house uses little daytime power, and exported surplus earns only 2.20 THB per unit under the PEA buy-back scheme — about half the ~4.3 THB you save by self-consuming. If the villa is rented out while you're away, the daytime loads (pool pump, aircon, cleaning) continue and solar still performs well. If it sits empty and unrented for months, size the system smaller or wait.
Is solar worth it without a battery?
Usually yes — if your electricity use is mostly in daylight hours. An on-grid system without a battery is the cheapest per kW and pays back fastest. A battery adds roughly 4,000–5,000 THB per kWh of capacity and makes sense when you have heavy evening consumption or want backup power during outages, not as a default.
Can I sell surplus electricity back to the grid?
Yes. PEA opened the 2026 household buy-back round on 1 July 2026: it pays 2.20 THB per exported unit on a 10-year agreement, capped at 5 kW AC per meter, with applications via ppim.pea.co.th until 30 November 2027. Because 2.20 THB is roughly half the ~4.3 THB per unit you save by using the power yourself, we size systems for self-consumption first and treat the buy-back as a bonus.
Do the panels really last 25 years in Thailand's climate?
Yes. Tier-one panels such as LONGi carry performance warranties of around 25 years and typically last 25–30 years, degrading at less than 1% per year. The realistic maintenance item is the inverter, which usually lasts 10–15 years and should be budgeted as one replacement over the system's life. In coastal Phuket we also specify corrosion-resistant mounting so the hardware lasts as long as the panels.
Related reading: Solar panel cost in Phuket (2026) · The 200,000 THB solar tax deduction · Selling power back to PEA · Hybrid solar & battery backup
Find out if solar is worth it for your roof
Bring us a recent electricity bill and we'll do this math for your actual house — free site survey, written savings estimate in THB, and a straight answer either way. We reply in English.
Pearl Solar Energy Co., Ltd. · Phuket, Phang Nga (Khao Lak) & Krabi · Mon–Sat 08:00–17:00