Solar power in cold desert: Ladakh’s abundant sun can be harnessed for renewable electricity generation and heating

Ladakh’s solar potential provides an opportunity for renewable heating, especially for buildings with spaces that do not have access to the southern sun. An example is the Indo-Tibetan Border Police (ITBP) campus in Leh, Ladakh. The campus utilises radiant heating technology to warm two four-storeyed buildings. The heating technology used is called Concentrated Solar Power. In this system, the sun’s radiation is focused onto a silver tray, where curved collectors capture the solar energy and heat a glycol-water fluid to temperatures between 45°C and 50°C. The heated fluid then circulates beneath the building floors through 20 mm pipes, warming the indoor space. A 35-kilolitre storage tank stores the heated fluid and circulates to provide heating even after the sun is gone. The radiant heating system maintains comfortable indoor temperatures between 15°C and 20°C even when the ambient temperature is extremely low at -30°C.

Apart from electricity, hot water demand is also a significant energy drain, especially for hospitality establishments. While a few of these establishments have installed solar water heaters for the purpose, most similar establishments still rely on diesel or kerosene boilers for hot water, contributing to increased emissions. Hence, a wider adoption of solar heating systems can help in this aspect.

Decentralised energy generation from sun

The region’s abundant solar wealth makes it ideal for the installation of solar panels. In Ladakh, 5.29 kWh/kWp of energy can be produced daily, meaning a one kWp solar panel can roughly generate 5.29 units of energy each day in Ladakh on an average. In comparison, areas such as Shimla, Delhi, and Bhubaneshwar have lower generation potentials, with daily outputs of 4.49 kWh/kWp, 4.0 kWh/kWp, and 4.0 kWh/kWp, respectively, making Ladakh significantly more productive for solar-based energy generation (Reference: https://globalsolaratlas.info/map). The Union government aims to leverage this potential by developing India’s largest solar field in Ladakh, with a capacity of 13 GW.

However, vast regions of the Union Territory are located in remote areas making it an ideal scenario to explore rooftop solar in a decentralised way. Despite this, the uptake of solar PVs in the region has not found many takers. According to environmentalist Sonam Wangchuk who works in the region, the high subsidy for electricity in the region has rather discouraged people from installing rooftop solar panels. He proposes that the subsidy be only provided to the strata of society that really need it, encouraging the rest to invest in rooftop solar PV installation.

The Leh City Climate Action Plan Net Zero by 2047 suggests a telescopic pricing regime for electricity in Leh. The tariff structure is designed to ease financial pressure on lower-income users, who typically consume less energy, while ensuring higher-energy consumers pay their fair share. Under the proposed model, users consuming less than 450 units would pay less than under the current system, and only those using more than 1,300 units a month would pay more than the current unsubsidised rates. This, in turn, can help encourage high energy consuming customers to invest in solar PVs to meet their energy needs.

The potential for solar-derived electricity also provides an opportunity for the transportation sector to reduce its emissions. A significant milestone for the region is the installation of Leh’s first electric vehicle (EV) charging station at the district motor garages on Khardung La road. The station is powered by 260

solar PV panels with a total capacity of 100 kWp and supported by an 860 kWh lithium battery storage system. The charging plaza is capable of simultaneously charging 10 EVs.

Towards a sunny road ahead

The Energy Conservation Building Code (ECBC) and Eco Niwas Samhita currently identify five climatic zones across India to guide building design based on local climatic conditions. Ladakh is classified under the cold region zone, alongside regions like Jammu & Kashmir, parts of Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh. However, Ladakh is distinct from these areas due to its unique climate, characterised by abundant solar radiation. Given this, it would be beneficial to establish a separate climatic zone for Ladakh, which takes its high solar potential into account. Integrating this into the building codes would not only help optimise energy usage but also reduce electricity demands significantly. Additionally, the codes should promote designs that maximise solar gain, with buildings oriented to capture sunlight from the southern side, while ensuring proper insulation on other facades to enhance thermal efficiency. This approach would further support sustainable energy solutions tailored to Ladakh’s specific needs.

Additionally, solar-powered renewable heating solutions must become the norm in institutional and commercial buildings. The ITBP building in Leh has proved the potential of such a technology, and more government buildings should lead the way in adopting these solutions for widescale adoption. The Leh City Climate Action Plan Net Zero by 2047 supports this approach through Intervention M5, focusing on retrofitting government buildings with energy-efficient solutions to reduce consumption as these buildings account for 12 per cent of electricity consumption in Leh.

To reduce energy consumption in Leh’s tourism-dependent economy, proactive measures should be implemented in hotels and homestays, which are key energy consumers. While energy control may not always rest with the operator, it is essential to introduce mandates into building bylaws that require all new commercial structures in the hospitality sector to integrate energy-efficient fittings, fixtures, and appliances including but not limited to solar water heaters. Additionally, energy efficiency audits should be made a prerequisite for obtaining occupancy and business approval.

The potential of passive solar techniques to enhance energy efficiency in Leh's buildings is significant, yet many newer buildings, particularly in developed areas, are unable to take full advantage due to poor orientation or inadequate surface area for capturing sunlight, mutual shading in denser areas could also

contribute to this. To address this, planning and building regulations must be updated to ensure that future developments are strategically oriented and spaced, allowing buildings to maximise their passive solar potential.

This is the second in a two-part series. Read the first part here