The Sun Pays Me 21% a Year
Electricity here is expensive and cuts out constantly. The fix turned out to be one of the best-returning asset I own.
Let me start with the problem, because it’s more visceral than a bill.
Electricity on Koh Samui is expensive and unreliable. It’s generated on the mainland and piped over through underwater cables, and it cuts out regularly. And since the household water runs on an electric pump, a power cut usually means sitting in the bathroom in the dark, with no water to flush. That’s the part the brochures leave out about island life.
Now the money, because that’s where it gets interesting.
A Western family here, in a house with a pool, burns about 60 kWh a day. At 6 THB per kWh, that’s roughly 11,000 THB a month - about $325 - just for electricity.
We put in a hybrid solar system: panels to generate power, batteries to store it, all tied into the grid. It runs the house off the sun by day, off the batteries at night and during outages, and only pulls from the grid when it has to.
It does three things. It keeps our lights and water running when the rest of the street goes dark. It cuts the electricity bill by about 90% - roughly 9,000 THB a month. And it feels good to run the house on clean power. But that last one is a bonus. It’s not why I’d do it again.
This is why I’d do it again: it’s not an environmental decision, it’s an investment - and a better one than most things I could put the money into.
The system cost 500,000 THB. It saves about 9,000 a month, call it 108,000 a year. That’s a 21% annual return, and it pays for itself in under five years. After that, the savings are pure yield for the 15-to-25-year life of the equipment. I don’t know many assets that reliably return 21% with almost no risk.
And it asks for nothing once it’s up. No moving parts. The panels last around 25 years, the batteries 10 to 15, the inverter 10 to 15, all under warranty for a good chunk of that. The rain washes the panels for free. You install it and it quietly pays you back for two decades.
Here’s what changed how I see it - a roof is just dead space - until you realize 2,500 hours of sunlight a year are landing on it, free, whether you use them or not. Solar is just the decision to stop letting them go to waste.
I look at it the way I look at anything else I’d put money into: what does it cost, what does it return, how long until it pays for itself. By those numbers, the sun is one of the best deals on the island.