Thermal energy sources, mainly biomass, fuel wood for cooking and heating, petroleum, coal, and derivatives, accounted for 62.4 percent of total energy consumption in 2022

Yangyel Lhaden

Since its installation in 2021 at the Ministry of Energy and Natural Resources to provide hot water for the ministry’s canteen, an indirect thermosiphon solar water heating system (SWHS) has generated over 365,000 litres of hot water.

The SWHS, along with 11.7-kilowatt solar panels, was installed in the ministry’s compound as part of the first phase of a renewable energy demonstration, which also aimed to build the technical capacity of the energy department’s officials.

An indirect thermosiphon SWHS is a technology that uses solar energy to heat the water. A water tank supplies water through pipes inside the solar panel, the water is heated and transferred to a geyser for storage. The water can stay hot for up to 12 hours.

The SWHS produces about 500 litres of hot water daily.

“There is not much difference of hot water production during winter and summer although the amount of hot water produced depends on sunlight,” an official said.

The installation of SWHS is part of project “Promotion of Renewable Energy and Energy Efficient Technologies in the Building Sector” funded by the Austrian Development Agency.


While Bhutan achieved close to 100 percent electricity access by 2019, a year ahead of the 2020 target, the country’s energy supply still leans heavily on thermal sources like biomass, petroleum, coal, and their derivatives.

Thermal energy sources like biomass which mainly consist of fuel wood for cooking and heating, petroleum, coal, and their derivatives accounted for a substantial 62.4 percent of total energy consumption in 2022. Energy consumption increased from 650,220 tonnes of oil equivalent ( TOE) in 2014 to 752,441 TOE in 2022, according to Bhutan Energy Data Directory 2022.

TOE is a unit used to compare different energy sources based on their energy content.

The solar water heating system is part of the Alternative Renewable Energy Policy of 2013, aiming to achieve the target of 3 megawatts equivalent energy generation from solar water heating systems by 2025.

As part of the first phase of the project, the department planned to install 45 SWHS units in public institutions (25), residential buildings (10), and commercial establishments (10). The SWHS units for public institutions were provided free of cost, while residential and commercial projects would contribute 40 percent of the cost.

However, an energy official said that not many commercial and residential beneficiaries opted for the SWHS mainly due to the upfront cost of the systems. So far, 37 public institutions and four private buildings have installed the systems.

The SWHS in the ministry’s campus was installed at a cost of Nu 450,000.

One of the beneficiaries of the SWHS in public institutions is Bjishong Central School in Gasa, where boarding students have the luxury of bathing with hot water since 2018.

The official said that from the installation of the systems, they found it beneficial not only in terms of cost savings from the use of electricity and fuelwood but also for the health and hygiene of school children, monks, and nuns. “To ensure the sustainability of the systems, we initiated the signing of a tripartite agreement among the department, beneficiaries, and supplier, clearly stating the roles and responsibilities of each party.”

On average, the SWHS in the campus saves about 570 kilowatt-hour (kWh) of energy per month that would otherwise be drawn from the grid for heating water in the canteen.  

This results in a monthly cost saving of Nu. 1,516—at a rate of Nu 2.66 per kWh.

The energy department official said that SWHS effectively utilised solar energy as an alternative to conventional hydroelectric power from the grid for water heating purposes. “In terms of reliability, use of SWHS is found to be reliable and cost effective compared to other conventional water heating systems.”

“We did not face any technical difficulties with SHWS in the campus until now but the system was found not to be functioning at its optimum level before use of pump in the system,” the official said.“Through this project, the technical capacity has been enhanced where more than 15 department officials, 50 beneficiaries and suppliers were trained on the SWHS technology.”

He said that now, major operation and maintenance of the system are being done by in-house engineers and technicians, while minor and basic operations are carried out by the beneficiaries. “We have further plan  to scale up the installation of SWHS in the country in the future.”