Solar Water Heater

Solar for Tourism


The availability of hot water, especially during winter seasons, is highly essential for our country, where more than 50% of our population resides in mountainous areas. Solar thermal technologies are quite relevant for mountainous regions, where the national electricity grid connection is not available due to the high cost for the same.

In this context, a few Nepalese companies have been manufacturing solar water heating systems (SWHSs), employing a rather simple kind of solar thermal collector (STC). Specifically, it adopts the black paint based solar absorber layer coated on a corrugated aluminium sheet. But this kind of STC is neither efficient nor durable. To upgrade the local product, we have been working since 2017 in collaboration with National Innovation Center (NIC). Our main focus has been on improving its solar to thermal conversion efficiency and also improving long-term durability. For this, in the first stage, we have prepared a small-sized proto-type SWHS that was fabricated, employing black nickel selective coating based STC and found that the new product shows more than 20% efficient than the SWHS with the black paint based STC.

Despite these encouraging statistics, we still require further evolution (in particular, for its application in space heating) to reach our target demographic of mid and high mountain dwellers. Considering this hypothesis, we further pursued the work to produce a commercial-sized product of 4×4.4 sq. ft and compared its performance with the black paint based local product. From the study of our commercial-sized product, we found that at low water flow rate the device showed equal performance, but at higher flow, our product showed about 10 % higher performance.

However, from our first product, we learnt several technical weaknesses on which we are working to address in the next product.


Everyone knows that Nepal government's investment in R&D for R&D based economy is negligible. I had been trying several funding agencies such as Ministry of S&T, UGC, Nepal and The World Academy of Science and so on. I succeeded to get funding from some of these institution and built some very preliminary foundation for this research. I came to know through interview of Mahabir Pun Dai that NIC is supporting the novel ideas! which encouraged me to approach and build a collaborative partnership between NIC and Kathmandu university (KU). As a first step of collaboration between KU and NIC, I have initiated this project in which the grant was used just to purchase the materials and tools required for the project.


To quantify the relative thermal performances (efficiency and stability) between black nickel substrate and black paint based solar thermal collectors.

Key Features

  1. As our product has better water heating capacity, it is more appropriate for hotels which require large amount of water.
  2. Because of permanent coating, our product is highly stable and requires very minimal maintenance compared to traditional home-made technology.


Our product's dimension is 4.5 ft x 4 ft x 0.4 ft and the weight is about 15 kg.

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