The annual energy consumption in Vietnam for 1990 was about 4.623 million tones of oil equivalent. This corresponds to an annual consumption of 70 kgoe per capita (.e., about 1667 MJ per capita), which was one of the lowest energy consumption per capita values in the world [2]. The percentage contributions of commercial forms of energy used in Vietnam in 1990 are shown in Fig 3. The breakdown of energy consumption in the various sectors is illustrated in Fig.4. In the domestic sector, the patterns of consumption are shown in Fig. 5. In this sector, 51% of energy is consumed for cooking, while the remaining 49% is divided between lighting and electrical appliances, including electrical water heaters. Electricity contributes 23% of the energy used in cooking and 55% of that in lighting and other electrical appliances.

However, the pattern of energy consumption in the domestic sector is changing dramatically. Coal is being replaced by natural gas for cooking in cities; the level of consumption for lighting and electrical appliances is increasing; and the demand for hot water and space conditioning is also increasing in the main cities. Figure 6 shows the pattern of energy consumption in a typical middle-income household in Hochiminh city [2].

Furthermore, the number of electrical hot water systems imported into Vietnam is increasing significantly. For instance, in Hochiminh city alone, for the first nine months of 1996, the number of imported electrical hot water systems with storage tank capacity ranging from 30 litres to 50 litres averaged 960 units per month [3]. This means that every month, the potential peak electricity demand on the grid system in this city alone increased approximately 1440 kW due to the installation of these hot water systems.

The above analysis indicates that if the Vietnamese government does not have a wise strategy to correct the trend of electrical water heating use, this could become an increasing burden on the already inadequate electricity supply in the coming years.

With the advantage of plentiful solar radiation, the introduction of solar water heaters could be part of the solution to this problem.