ENG / VIE

Solar Thermal

Solar thermal systems are used under tropical climates for years, as it is a reliable and simple way to heat up water for domestic or industrial use.

Unlike solar PV, this technology is used to heat up water, and do not generate power. It exploits different wavelengths of the sunrays, through simple thermal processes (greenhouse effect inside solar collector) and reaches higher efficiency for energy conversion compared to solar PV.

A solar water heating system includes solar collectors and a storage tank. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t.

Typical design of a solar water heating system for domestic hot water (active system)

Typical design of a solar water heating system for domestic hot water (active system)

Two main types of solar collectors are used:

  • Flat-plate collector
    Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors — typically used for solar pool heating — have a dark absorber plate, made of metal or polymer, without a cover or enclosure.

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  • Evacuated-tube solar collectors 
    They feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin.
Solar thermal system for an industry in Tien Giang province (Source: Promoting the Concept of Eco Industrial Park in the Mekong Delta (ARTELIA, Enerteam, 2014).

Solar thermal system for an industry in Tien Giang province (Source: Promoting the Concept of Eco Industrial Park in the Mekong Delta (ARTELIA, Enerteam, 2014).

Solar thermal systems are generally speaking a cost-effective way to produce hot water for domestic or industrial application. Payback times of such solar projects in Vietnam have been noticed as being below 5 years, with very competitive cost.

However, quality issues for products in Vietnam has been observed (no national certification of products or company), which can affect negatively the entire image of solar energy.