Is solar actually worth it in Thailand? An honest look

Sometimes yes, sometimes emphatically no. The deciding factor is not your roof, your budget or the brand of panel on your quote — it is when you use electricity. Here is the arithmetic, without the sales gloss.

What a unit of electricity is actually worth

Thai residential electricity averaged around ฿3.95 per kWh for the May–August 2026 billing period, including the Ft adjustment and before VAT. Add 7% VAT and the blended effective rate lands near ฿4.23 per kWh. The previous period, January to April 2026, averaged ฿3.88. Residential tariffs are progressive, so heavier households pay more per unit than light ones — which is precisely why big consumers see the strongest case for solar.

Now the part that decides everything. Under the PEA and MEA household rooftop scheme for 2026, surplus power exported to the grid is paid at ฿2.20 per kWh.

The scheme itself has firm limits worth knowing before you plan around it: residential properties only, a maximum of 5 kW AC, roof-mounted systems only, a 10-year contract, a ฿2,000 application fee excluding VAT, an application window running from 1 July 2026 to 30 November 2027, and a national programme cap of 500 MW. If you are not registered under the scheme, any surplus you push into the grid simply leaves your property and earns you nothing at all.

How much a Phuket roof really produces

Across Thailand, a well-installed system typically yields 1,300–1,500 kWh per kWp per year, or roughly 3.6–4.1 kWh per kWp per day. Southern Thailand, Phuket included, sits at the lower end of that band because of heavy rainfall and extended cloud cover through the monsoon months.

That matters when you read a quote. A proposal built on 1,500 kWh per kWp will overstate a Phuket system's output by around 15% compared with one built on 1,300. Neither figure is dishonest in itself, but only one of them is realistic here. We size on the conservative end, because an estimate that disappoints in September is not much use to anybody.

What a system costs

Indicative installed costs in Thailand, varying with roof type, access, equipment and the amount of electrical work needed:

System size	Indicative installed cost
3 kW	฿90,000 – ฿170,000
5 kW	฿130,000 – ฿250,000
10 kW	฿250,000 – ฿430,000

Those bands are wide for a reason: a straightforward metal-roof install with a short cable run and a modern consumer unit sits near the bottom, while a tile roof, difficult access, long runs and switchboard upgrades push towards the top. Adding battery storage roughly doubles the cost of a system. We break the pricing down further in how much solar costs in Phuket.

Worked examples: three households

Take a 5 kWp system in Phuket at the conservative yield of 1,300 kWh per kWp — about 6,500 kWh a year. The only variable below is how much of that generation each household consumes on site rather than exporting.

Household	Self-used	Annual value with export contract	Annual value without export contract
Out at work all day, no battery	~20%	~฿16,900	~฿5,500
Someone home part of the day	~50%	~฿20,800	~฿13,700
Home office, daytime air-con, pool pump	~80%	~฿24,700	~฿21,800

Two things jump out. First, the household that is home during the day earns roughly four times as much as the absent household when no export contract is in place. Second, even with an export contract accepted, the daytime-heavy household is still meaningfully ahead — and it gets there without depending on a scheme that has a national cap, a closing application window and a 10-year contract attached.

Set those figures against the installed cost band and the payback arithmetic is straightforward. A 5 kW system at the lower end of the cost range, in a daytime-heavy household, pays for itself in roughly six years. The same system at the top of the cost range, in a household that is out all day with no export contract, would take several decades — which is another way of saying it should not be built.

These are guidelines, not quotations. Your own figures move with your tariff band, your roof orientation, shading, equipment choice and how your household actually behaves. The savings calculator will get you to a ballpark in a couple of minutes.

When solar is not worth it

We would rather lose a sale than install a system that disappoints. These are the situations where we will usually say so:

• Your usage is mostly in the evening and you do not want a battery. If the house is empty from eight until six, an unstoraged array spends its day exporting at ฿2.20 — or, without a contract, giving power away. A battery fixes the mismatch but roughly doubles the cost, which pushes payback back out again. Sometimes the honest answer is a small system, or none.
• Your bill is genuinely low. Below a certain consumption, the fixed portion of an install — mounting, electrical work, labour, paperwork — never gets recovered, because progressive tariffs mean light users are also paying the cheapest rate per unit.
• You rent, or the lease is short. Payback runs into years. Unless the landlord is paying or the value transfers with the property, the numbers rarely work for a tenant.
• Your roof needs replacing within a few years. Panels are a 25-year commitment on a roof that must last as long. Removing and refitting an array later costs real money, so it is usually better to do the roof first.
• You have heavy shading. Trees, water tanks, neighbouring buildings and parapets can strip a serious share of annual output. Optimisers and careful string design help, but they do not manufacture sunlight.

How to tell whether a system is performing

The measure that matters is the performance ratio: how much of the theoretically available energy your system actually delivers, after heat, dust, cable losses and inverter conversion. A good new install in Thailand should run at 78–85%. Anything persistently below 75% signals a problem — soiling, shading that was not accounted for, a failing string, an undersized or misconfigured inverter, or simply poor workmanship.

It is worth asking any installer what performance ratio they design to, and what happens if the system does not reach it. The answer tells you a great deal.

So — is it worth it?

For a Phuket household that uses a decent share of its power in daylight — families at home, people working from home, villas running pool pumps, air conditioning or staff during the day — solar is one of the more reliable investments available, and it gets better every time tariffs rise. For a house that is empty all day and unwilling to pay for storage, it is a much weaker case, and no amount of enthusiasm from a salesperson changes that.

The way to find out which one you are is not a brochure. It is your own bill, your own roof and an honest look at your daily routine. We are happy to do that with you: read more about home systems or commercial installations, run your numbers through the calculator, or simply get in touch and we will tell you plainly whether it stacks up. If it does not, we will say so.