Off-grid power, explained simply.
Five minutes, no jargon. By the end you'll know what's in a system, what it can run, and how big yours needs to be.
The four building blocks
Think of your system like a water tank at home. Every off-grid system, from a garden hut to a resort, is made of these four parts.
Make power
Solar panels, wind, a generator or the mains are the rain that fills your tank. The charge controller is the float valve: it stops by itself when the battery is full.
Charging →Store power
Batteries are the water tank. A bigger tank keeps you going longer after dark. Use about half each day and it stays healthy for years.
Batteries →Convert power
Batteries hold 12V or 24V DC. Your fan and TV want 230V, like a wall socket. The inverter changes one into the other, instantly and quietly.
Inverters →Protect and watch
Fuses and breakers are the safety valve. A battery monitor is your fuel gauge, showing how full the tank is right now.
Monitoring →What can it run?
Typical power and daily use for appliances in Thai homes. Add up the watt-hours (Wh) for everything you want, and that's your daily energy. The finder does this for you.
| Appliance | Watts | Hours a day | Wh a day | Good to know |
|---|---|---|---|---|
| LED light | 10 | 5 | 50 | |
| Fan 16" | 50 | 8 | 400 | |
| TV 32–43" | 60 | 4 | 240 | |
| Fridge 5–7 cu ft | ~100 running, ~42 average | 24 | 1,000 | Starts at around 5× its running power |
| Wi-Fi / 4G router | 10 | 24 | 240 | |
| Laptop | 60 | 4 | 240 | |
| Home water pump | 250 | 1 | 250 | Starts at around 3× |
| Farm pump ½ HP | 370 | 2 | 740 | Starts at around 5×; run it at midday |
| CCTV, 4 cameras + recorder | 40 | 24 | 960 | Check the label on your recorder |
| Rice cooker 1.8 L | 700 | 0.75 | 525 | Needs a 1,000W+ inverter |
| Washing machine | 450 | 0.5 | 225 | Starts at around 3× |
| Microwave | 1,000 | 0.2 | 200 | Needs a 2,000W inverter |
| Electric kettle | 1,800 | 0.2 | 360 | Needs a 2,000W+ inverter |
| Inverter air-con 9,000 BTU | ~650 average (900 max) | 4 | 2,600 | Best on sunny afternoons or with grid/generator |
| Inverter air-con 12,000 BTU | ~850 average (1,200 max) | 4 | 3,400 | As above |
| Instant water heater | 3,500–6,000 | — | — | Too big for batteries — gas or solar hot water is the easy answer |
Sizing a system in four steps
Add up your daily energy
List what you want to run, multiply watts by hours, and add it up. 3,000 Wh is 3 kWh, or three “units” on an electricity bill.
Size the battery bank
Divide the daily energy by the system voltage, then double it so you only use about half each day. Example: 1,200 Wh ÷ 12V = 100Ah, so a 200Ah bank. Add more for cloudy days.
Choose the inverter
Add up everything that might run at the same time, add a margin, and check it covers starting surges from fridges and pumps. Pure sine wave keeps motors cool and quiet.
Plan the charging
Solar panels sized for rainy-season sun (about 4 strong hours a day in the south), plus a generator or mains charger if you have one.
12V or 24V?
You don't need to choose — the finder does. As a rule of thumb, 12V suits small cabins, backup systems and anything under about 2 kWh a day; 24V suits bigger homes because it halves the current, so cables stay thinner and cooler. The exception is a system built around a 12V inverter-charger with the solar inputs built in, such as our Resort Villa Kit: it stays at 12V with four batteries in parallel and heavier cables, which we size and supply. Very large systems use 48V banks of 2V cells, which we design with you.
Sealed batteries or lithium?
Both are great at different jobs. Sealed AGM batteries like Fullriver's are simple, robust, need no battery management electronics, ship easily by road and ferry, and shine in backup, standby and generator-charged systems. Lithium is lighter and happy to be used more deeply each day. We supply Fullriver sealed AGM and 2V cells, and we'll always tell you plainly which suits your place.
Batteries and Thai heat
Batteries love shade. Keep them in a ventilated room or cabinet, away from a hot roof or direct sun, and they'll reward you with years of service. Every compatible KISAE charger we fit can take a temperature sensor, which adjusts charging automatically as the day warms up. Using about half the battery each day and recharging fully is the other half of the secret.
Plain-English glossary
Watt (W)
How much power something uses right now. A fan uses about 50W.
Watt-hour (Wh) and kWh
Power × time. 1,000 Wh = 1 kWh = one unit on your electricity bill.
Volt (V)
Electrical pressure. Batteries are 12V or 24V; wall sockets are 230V.
Amp-hour (Ah)
Battery size. 100Ah can give 5A for 20 hours.
Inverter
Turns battery power into 230V household power.
Inverter-charger
Inverter and battery charger in one; switches over by itself when mains or a generator is on.
Pure sine wave
Clean power just like the mains, kind to fridges, pumps and electronics.
Charge controller
Sits between panels and battery and charges it correctly.
Deep-cycle battery
Made to be used and recharged every day, unlike a car starting battery.
AGM
A sealed battery: no topping up, no spills.
Depth of discharge
How much of the battery you've used. Around half a day keeps it healthy.
Surge
The short burst of power fridges and pumps need to start.
Peak sun hours
Hours of full-strength sun a day; about 4 in Thailand's rainy season.
Battery monitor
Your fuel gauge: shows how full the battery is.
Questions and answers
Can I run air-conditioning on batteries?
Yes. An inverter air-con for a few evening hours works well on our larger systems. For cooling all night, pair it with the mains or a generator; the finder sizes that for you.
Does solar work in the rainy season?
Yes. Thailand still gets about 4 strong-sun hours a day in the wettest months. We size for rainy-season sun, so the dry season gives you spare.
Do I need permission for an off-grid system?
A system that isn't connected to the grid doesn't need the power company's approval. Anything wired into your house should still be connected by a licensed electrician.
Do you sell solar panels?
Your system result tells you exactly which panels and how many watts to add. Ask us on LINE and we'll quote matching panels and mounting.
12V or 24V: which do I need?
The finder chooses for you: 12V for small and backup systems, 24V for bigger homes, where it keeps cables thinner.
Will it switch on by itself when the mains goes off?
Yes. KISAE inverter-chargers switch over in a blink, so most devices carry on, then recharge the batteries when the mains comes back.
What size generator do I need?
Your result recommends one. Typically about 3 kVA suits a bungalow and 5 kVA a villa. A KISAE charger then refills the batteries quickly and cleanly.
Are the batteries safe indoors?
Fullriver AGM batteries are sealed and maintenance-free. Keep them in a shaded, ventilated spot and always fit the fuse we specify.
How much maintenance is there?
Very little. Sealed AGM needs no water. Glance at the monitor, keep the terminals clean and tight, and give a full charge at least weekly.
Can I add more later?
Yes. Panels, a generator charger or monitoring can be added any time. Buy the battery bank together so the batteries age evenly.
Is it noisy?
Batteries are silent and inverters hum gently. It's far quieter than running a generator all evening.
What if I'm not sure what I need?
Answer six quick questions in the finder, or send a photo of your appliance labels on LINE. An engineer checks your system for free.
Charging a resort buggy fleet off-grid
On an island resort the buggies are often the biggest single load on the power system, and the easiest to plan for, because they charge at the same time every night.
A 48 V resort buggy on a six-battery 8 V set holds roughly 8 kWh and in shuttle duty uses about 2–4 kWh a day, so a fleet of ten buggies needs 20–40 kWh put back every night. To make that from the sun you need, at Thailand's average of about 4.5 peak-sun hours and a 25 % allowance for heat and wiring, roughly 6–12 kW of panels, and because the buggies charge after dark the energy has to pass through a storage bank first: a bank that can give up 30 kWh at a 50 % cycle is about 60 kWh of sealed AGM, which is where the Fullriver HGXL 2 V cells earn their place. Charge the buggies in the late afternoon instead, straight off the solar, and the storage bank shrinks by most of that. Either way the buggies' own batteries matter as much as the system: a sealed AGM set such as the Fullriver EGL accepts charge faster than a flooded set, so the fleet is full sooner and the generator runs less. The sets themselves, picked by cart model, are on our vehicle side at Drake SVO: golf cart and resort fleet batteries, with the buyer's guide covering how many batteries each cart takes and what they cost. Tell us the number of buggies, their battery count and when they charge, and we size the solar, the bank and the chargers as one system.
Ready to size yours?
Six quick questions, a complete system with prices, and a free check by an engineer.