Technology
Solar water heaters
Evacuated tubes or a flat collector heat water directly with the sun. Simple technology: a square metre of roof gives 2–3 times more heat than a square metre of panels gives electricity.
Price from: 6.85 m ₫ Vietnam
How it works
A collector on the roof heats water or antifreeze; the hot water rises into the tank on its own (thermosiphon) or a pump moves it. China and India mostly install evacuated tubes, Europe flat collectors.
Estimated output for a home (IEA SHC): Jerusalem — 1,024 kWh of heat per 1 m² a year, Antalya — 910, Shanghai — 592, Moscow — 443. A home usually has 3–6 m² of collectors and a 150–300 l tank.
About 544 GW of thermal capacity is in operation worldwide, but in 2024 the market shrank by 14%: in homes, panels with a heat pump are pushing collectors out.
Pros
- A thermosiphon needs no pump and no electronics
- A cheap way in
- Lots of heat per square metre of roof
Cons
- Only hot water and preheating
- Gives little in winter in the north; risk of freezing
- Overheats in summer if the water is not used
- Panels with a heat pump are more flexible
Sizes and figures
| Heat per 1 m² a year (IEA SHC) | Moscow 443, Shanghai 592, Antalya 910, Jerusalem 1,024 kWh |
|---|---|
| Per home | 3–6 m² of collectors, a 150–300 l tank |
| Types | evacuated tubes (59% of new systems), flat plate (34%) |
| Layout | thermosiphon (39% of new ones) or pumped with antifreeze |
Starting prices
Benchmarks with a source and a date. The price for your property comes in the estimate after a site survey.
| What | Price | Source |
|---|---|---|
| Solar water heater, 160–180 l Vietnam | 6.85–7.66 m ₫ | Điện Máy Xanh: máy nước nóng năng lượng mặt trời · 24.07.2026 |
Russia and Vietnam
Russia case by case
For a dacha and the summer season it is a good, simple option. In winter it needs a pumped layout with antifreeze, and the solar share is small.
Vietnam relevant
The climate is like that of this market’s leaders: in the south, water heats all year round. A 160–180 l tank with tubes costs 6.85–7.66 million ₫. By the sea and in the typhoon zone you need strong mounting and durable materials.
When it is worth it and when it is not
Worth it
- Lots of hot water during the day: a family, a guesthouse, a café
- The south and the tropics
- A dacha in summer
Not worth it
- Hot water is needed in winter in the north
- The roof is in shade
- You already have panels with a surplus — it is simpler to send it to a heat pump or an immersion heater
Safety and rules
A 150–300 l tank full of water weighs 200–350 kg: check the roof first.
At the outlet — a mixing valve against scalding, and overheating protection.
Sources (3)
Goes well with
Heat pumps
A heat pump moves heat from the air or the ground into the house: 3–4 kWh of heat per 1 kWh of electricity over a season. It pays off where homes are heated with electricity, LPG or diesel.
Solar panels
Modules on a roof, a façade or the ground turn light into electricity. The cheapest new electricity in the world — but only by day and with big seasonal swings.
Request for supply and installation
Describe the property — we’ll calculate it and reply, usually within two working days.