Summary

Mongolia: Heating with solar power

atmosfair is financing and installing photovoltaic systems and electric heating systems in Mongolia, enabling institutions such as kindergartens and schools to switch from heating with coal, which is harmful to the environment and health, to solar power.

The photovoltaic systems are designed in order to produce as much electricity as is needed for heating over the course of the year. In winter, additional electricity should be drawn from the grid, and in summer the same amount of solar electricity should be fed into the grid.

Electric heating

The first two photovoltaic electric heating systems were started up at the beginning of October 2023. These are “twin” kindergartens in Ulaanbaatar, i.e., two kindergartens in the same location in two neighboring quasi-identical buildings. Here we are testing two approaches to electric heating:

In Kindergarten A, we use a water-based heating system with heating rods to convert electricity from the 50 kWp photovoltaic system into heat. This is temporarily stored in latent heat storage tanks, where heat is stored as waxes melt and released as the waxes harden. This allows solar power to be used effectively in winter even without being fed into the grid. The heat is conducted in insulated water pipes to the radiators in the individual rooms.

The second heating system in Kindergarten B uses the electricity from a 20 kWp photovoltaic system to directly and efficiently heat the individual rooms with 19 air-conditioning units, i.e. air-to-air heat pumps. As the name implies, the heat pumps pump heat from the outside air into the inside air of the buildings. In a compressor circuit, low pressure causes a refrigerant to evaporate in the air conditioner’s outdoor unit. In the process, it extracts heat from the ambient air. This also works at temperatures below zero. In the indoor unit of the air conditioner, the coolant is compressed under high pressure and condenses. The heat is thereby released into the interior air. If an air conditioner is operated in cooling mode, the process is reversed. Commercially available refrigerators work on the same principle.

A study with a total of 7 households already showed in 2019 that efficient heating with modern air conditioners is even possible in very cold Mongolia . Even at the lowest temperatures, the air conditioners were still slightly more efficient than heating rods (100% efficiency) and produced an average of 2.8 kWh of heat for every kWh of electricity during the entire heating period. This is also referred to as a SCOP (seasonal coefficient of performance) of 2.8. In Germany, values between 4 and 5 are possible due to the milder winters. The photovoltaic system for Kindergarten B could therefore be dimensioned smaller than the one for Kindergarten A.

Mongolia and solar energy

Mongolia covers about 90% of its heating energy with domestic coal. Besides the immense environmental and climate impacts, air pollution, which is primarily caused by burning coal, is responsible for about 3300 premature deaths each year in Ulaanbaatar alone. Switching to solar electric heating can provide a sustainable solution.

Winter in Mongolia is cold. With an average annual temperature of -2°C and lows as low as -40°C in winter, Ulaanbaatar is the coldest capital city in the world. At the same time, photovoltaic systems produce about 1.8 times more electricity than systems of the same size in Germany (about 1800 kWh/kWp/year vs 1000 kWh/kWp/year) due to the stronger solar radiation at lower temperatures. If the solar plants are steeply elevated (45-50°) and oriented to the south, they produce as much electricity in the high altitude areas of Mongolia even in winter as in summer. In comparison: the solar output in Germany drops in winter to about 1/3 of the output in summer. Therefore, about 75% of the solar power can be used for heating in Mongolia, even without seasonal storage.

Prospects

After evaluating the two different electric heating systems in the first winter, it is planned to extend the project to other institutions. In order to reduce the subsidy share and enable scaling, the feed-in tariff for the solar electricity produced will be of decisive importance in the future, in addition to cost optimization.

Partner

kraftBoxx GmbH is specialized in Power2Heat and latent storage systems. kraftBoxx manufactures the water-guided heating systems including heating rods and latent storage. Together with the Mongolian partner Solar Energy Consulting LLC, kraftBoxx is responsible for the assembly, installation and monitoring for the solar electric heating systems of the kindergartens.

The NewClimate Institute (NCI) is a non-profit organization that develops ideas for climate protection and promotes their implementation. The NCI co-funded the solar electric heating system with the air-to-air heat pumps.

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