The social development and the improved living standards induce the increased demand for energy. Therefore, energy savings are essential requirements for domestic use, production and life in order to ensure energy security of the country, supporting the process of socio-economic development with sustainability.

Using renewable energy such as solar energy, wind energy is  the solution to bring about many practical benefits. In particular, the solar hot water heater is so popular that it is widely used by so many households.

The solar radiation is absorbed through vacuum glass tubes or thermal panels of a boiler, converted into energy to heat water for daily serve. Therefore, the use of solar hot water heater brings about many benefits, such as less power consumption, ensuring regular supply of hot water, producing no noise, low maintenance costs and high durability.

During the recent years in Ha Giang, households have been familiar with the use of solar water heaters. According to Mr. Phung Van Quang (Group 3, Nguyen Trai Street. Ha Giang city), his family of 5 people pays VND250,000 - 350,000 each month for electricity bill. In his calculation, the electricity bill is low thanks to his using solar hot water tank installed 3 years ago. The resulted hot water is  used not only for bathing, but also for cooking and washing dishes, to support his family while also time and power are saved.

Mr. Quang said, many households in the area and he had also installed solar water heaters using solar energy thanks to the advantages of this device: electricity saving for long term, and its usage throughout the year. 

Solar water heater is equipped with storage tank to maintain the hot water in the cloudy, rainy and stormy days. The average heating is from 20 - 40 liters, equals to a capacity of 2/3 conventional water heaters. The insulated tank keeps the water warm for about 3 days. The average water temperature is always higher than the outside temperature around 5-10 Celsius degrees, so in cold days, the warm water is still available for domestic use.

According to the producers, to use solar water heater effectively, users need to select products with a capacity to match the demand. For households from 2-3 people, it is recommended to use solar hot water tank of 140 liter capacity. Households from 3-4 people should use a capacity of 160 liters - 180 liters, and 200 liter tank and 240 liter tanks are designed for 4-5 person households.

However, the initial cost for solar hot water is often 2 - 3 times higher than the normal water heater. Consequently, many households are reluctant to make investment. In fact, with the power saving value, the investment could be returned only after about three years.

Trong Tan