The Road to Improved Solar Drying: Barriers and Drivers for Wider Adoption of Solar Dryers in Rural Bhutan

Abstract

In Bhutan, post-harvest losses are a significant challenge for many small scale farmers, especially in rural areas. Since these losses impact the ability to preserve foods during the peak harvesting seasons, this has a wide range of consequences, both for the farmers themselves and for the country as a whole. It contributes to food insecurity, economic uncertainty and the nutritional deficiencies that are prevalent among the rural population, and it makes the country more reliant on foreign imports. The existing widespread traditional method to conserve food – which is to dry it directly under the sun – is problematic due to its unprotected and uncontrolled nature, where contamination, insect infestations or sudden rainfall can quickly ruin an entire batch of vegetables or fruits. Additionally, the direct sunlight causes nutrient degradation in the foods, and the drying process is slow. This is especially an issue during the summer monsoon season, when most of Bhutan’s agricultural output occurs.

This thesis is a part of an ongoing project called SolarFood, which aims to help mitigate these issues by developing affordable, efficient and locally adapted indirect solar dryers, taking socio-economic factors heavily into account. In this study, barriers and drivers for wider adoption of the technology is investigated among small-scale farmers in rural Bhutan. This is done through a combination of literature studies, ministry and authority interviews, as well as extensive field studies across three dzongkhags (regions).

During the study, a wide variety of factors emerge that influence adoption of solar dryers within the target demographic. These include technical, social, economic, infrastructural, cultural and political aspects. 22 barriers and 30 drivers are identified, which can be broadly classified into seven categories. The findings highlight that certain barriers against widespread adoption are particularly influential, including lack of awareness, high investment cost, geographical challenges, limited infrastructure causing inaccessibility, uncertain market conditions, low technical expertise, regional variability in dryer suitability, as well as technical limitations of the dryer preventing year-round usage.

On the other hand, there are also multiple drivers that show high potential for accelerating adoption of solar dryers. Out of these, many are related to increasing awareness and confidence in the technology, for instance through information spread, availability of technical support and training, and getting first-hand experience with the dryer. Other important drivers include financial support through governmental initiatives such as cost-sharing, adapting the dryer further to local conditions, and improvements in road and market access. Modifications to the dryer suggested by farmers and other stakeholders – such as increasing its water resistance and portability in certain regions, incorporating a solar panel, or possibly turning it into an electricity hybrid to enable continuous usage during the monsoon – are discussed in relation to aspects such as affordability, technical complexity and material availability.

Overall, the study reveals that the adoption process of solar dryers in Bhutan is highly complex, with a large number of barriers and drivers that are closely interconnected. It is likely not an effective strategy to address each underlying cause for slow adoption in isolation; instead, a holistic but systematic approach should be used to increase the demand and rate of adoption. Socio-economic factors and local adaptation remain as critical factors for the project, both for the successful implementation of solar dryers in Bhutan, and for ensuring that the Bhutanese population yields the maximum possible benefits from the technology.

Popular Abstract

Challenges and Possibilities for the Use of Solar Dryers in Bhutan

Agriculture is the largest source of employment in Bhutan, and almost two thirds of the population in rural areas work with farming. However, many people in the country still suffer from nutrient deficiencies and insufficient access to food. The challenging climate, combined with the rough and steep terrain, makes farming difficult in most areas. Additionally, the produced food does not always reach the table, partly because of poor preservation and storage techniques leading to lots of food going to waste after harvesting. This causes serious problems for the country as a whole, and its possibilities for social and economic development.
Traditionally, food in Bhutan is conserved by leaving it out to dry directly under the sun, which exposes it to dust, dirt, fungi, insects and animals, as well as sudden rain or wind, while it is being dried. Not surprisingly, this causes a large portion of the food being ruined, but the direct sun exposure also destroys some important vitamins inside the food. To reduce these post-harvest losses and increase the nutrient value of the dried food, the SolarFood project is developing affordable and locally adapted solar dryers, where the food is protected inside a chamber during the drying phase. Hopefully, this will make nutritious food available for more Bhutanese people throughout the year.

However, even though the improved solar dryers show great potential minimising the lost food compared to traditional drying methods, not many farmers are using it. Why is it so? And what can make more people use this technology? This was some of the questions we wanted to answer when we travelled to Bhutan. There, we went on a field trip to interview both ministries and other stakeholders within the agriculture sector, as well as farmers and carpenters in different parts of the country. Through these studies we understood that Bhutan is a vastly diverse country, where the climate, culture and agricultural practices vary a lot in the different regions. This makes it hard to design one solar dryer that is perfect for every farmer in Bhutan. It was for example very important for some of the farmers that the dryer was big enough for their whole harvest, while yak herders at higher altitudes needed a more lightweight version that they could carry up to the mountains. Among the farmers who were trying out the solar dryer, they were overall happy with the performance, but many of them had problems drying their food during the monsoon season when it rains a lot. They said it would be beneficial if the solar dryer was waterproof or could be used in really bad weather – which is something that is missing in today’s version.

However, even if the design improves, nothing will change unless people become aware of the technology. During the study, it was discovered that most farmers had never heard of this type of solar drying technology. Therefore, it is crucial to find ways of spreading information and make the dryer accessible for everyone. Farmer cooperatives, local agricultural extension offices and governmental initiatives were often mentioned as good starting points to get the snowball rolling, and for the word to start spreading mouth-to-mouth. Hearing someone who has tried the technology talking positively about the experience is the most effective way of spreading information and interest.
We hope that this thesis can be a start of the process of spreading information and awareness of this technology, as well as contribute to further improvements based on the farmers’ requests.

• author: Andreasson, Noah and Lundevaller, Linda
• supervisor: Martin Andersson
• organization: Department of Energy Sciences
• course: MVKM01 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Bhutan, Solar Dryer, Post-Harvest Losses, Renewable Solutions, Solar Energy, Agricultural innovation, Technology Adoption, Food Conservation, Food Security, Nutrition Access, Sustainable Agriculture, Climate Resilience, Rural Farming, Rural Development
• report number: ISRN LUTMDN/TMPH-25/5658-SE
• ISSN: 0282-1990
• language: English
• id: 9209595
• date added to LUP: 2025-08-11 14:19:19
• date last changed: 2025-08-11 14:19:19