Choosing between an ETC and FPC solar water heater is the single most important decision any solar buyer faces. Get it wrong and you end up with scale buildup, poor performance on cloudy days, or a system that can't deliver pressurised water to your upper floors. Get it right and you have free hot water for 20+ years.
What is an ETC system?
An Evacuated Tube Collector (ETC) uses rows of double-walled borosilicate tubes. The inner absorber tube is coated with a 3-target layer of Aluminium, Copper, and Nickel and sealed within an outer glass tube with the air evacuated — creating a vacuum that eliminates heat loss. The result is a system that absorbs solar energy efficiently even on cloudy days and loses almost none of it to the environment.
ETC advantages
- Hard water compatible up to 3000 PPM — essential for hard water regions worldwide
- Works in diffuse light — important in any region with seasonal cloud cover
- Zero maintenance — sealed tubes, no moving parts
- Water stays separate from collector — no internal scaling risk in tubes
- Available 100–500 LPD for homes and guesthouses
What is an FPC system?
A Flat Plate Collector (FPC) uses a copper riser-and-header pipe network bonded by continuous ultrasonic welding to a selective-coating absorber plate under toughened glass. The key advantage is that it can be plumbed as a pressurised system — delivering hot water at mains pressure to any floor of a building.
FPC advantages
- Pressurised delivery (3 Kg/cm²) — hot water reaches any floor without a booster pump
- Scales to 1000 LPD with 8-collector arrays for hotels and apartments
- Ideal for soft water areas (TDS under 200 PPM)
- 97% light transmittance frosted toughened glass
The buyer's decision matrix
| Your situation | Recommended system |
|---|---|
| Home in a hard water region (TDS above 200 PPM) | ETC Diamond Glassline |
| Coastal home, soft water, salt air environment | ETC Eco Deluxe (SS 304-L) |
| Apartment or multi-storey flat | FPC Pressurised (PRD) |
| Hotel, resort, hospital (large capacity) | FPC Pressurised array |
| Guesthouse / homestay, hard water region | ETC Diamond Glassline 300–500 LPD |
Key technical differences at a glance
| Specification | ETC | FPC |
|---|---|---|
| Water hardness tolerance | Up to 3000 PPM | Up to 200 PPM |
| Pressurised supply | Non-pressurised (gravity) | Both PRD and non-PRD |
| Cloudy day performance | 40–60% output | Requires more direct sun |
| Max capacity | 500 LPD (38 tubes) | 1000 LPD (8 collectors) |
| Maintenance | Zero | Periodic inspection |
| Output temperature | 70–90°C | 70–90°C |
Not sure which system is right for your location and water type?
Ask Hydrolux Solutions