Solar Dryers: Improved food security and Reduce post harvesting loss

The most common approach to preserve freshly harvested cereals, fruits and vegetables is to dry and store them. Solar energy has been used for centuries for drying crops, heating buildings and other products.

Solar Dryers: Improved food security and Reduce post harvesting loss  
Solar Dryers: Improved food security and Reduce post harvesting loss


One of the main concern is the post-harvest loss of agricultural commodities in many developing countries. A significant amount of agricultural production is wasted in many countries due to lack of proper knowledge on benefits of using simple post-harvest and conservation technologies. With introduction of appropriate post-harvest technology, it helps in saving the wasted food and also add value on the quality of products that result in a high market price.

The most common approach to preserve freshly harvested cereals, fruits and vegetables is to dry and store them. Solar energy has been used for centuries for drying crops, heating buildings and other products. Open sun drying is one of the oldest uses of solar energy drying and preservation of agricultural surpluses. The methods used are simple, but it is not free of problems such as the high dependency on weather conditions, slow drying rates, the risk to contamination, affected by high levels of dust and atmosphere pollution and the process is labor intensive. Solar powered drying can reduce the moisture content of agricultural products more effectively and hygienically and can be stored for longer periods. Solar dryers have significant potential to be integrated into agricultural value chains, from very small to large-scale applications. Furthermore, it also offers a highly effective and practical means of preservation to reduce post harvest losses and offset the shortages in supply. The solar dryer enables control of the drying process so that high-quality dried products can be sold in distant markets. This creates new business opportunities for smallholder farmers in remote areas.

Solar Dryers in Nepal:

Nepal has over 300 sunny days in a year giving high potential of solar energy use. On average Nepal has 6.8 sunshine hours per day with the national average is about 4.7 kWh/m2/day and there is a huge potential for solar water heaters, solar dryers and solar cookers[1]. The application of solar drying systems has been introduced in rural Nepal for the preservation of food and income generating activities. The Research Centre for Applied Science and Technology (RECAST) conducted a nationwide survey and revealed that three types of solar drying systems were in common use: cabinet type for domestic use, racks type for commercial and tunnel type for industrial purposes. Though, the solar water heaters have been fully commercialized, and by 2009 more than 185,000 units have been installed so far, however the solar dryers and cookers are still not in the phase of commercialization.

Market Potential for the Technology

Fruits, vegetables and meat dried in a solar dryer are better in quality and hygiene compared to fruits, vegetables and meat dried in traditional method. Contamination of food is prevented or minimized due to the closed system design. Furthermore, the products are not vulnerable to rain, dust and air pollution, compared to the open system traditional drying. The technology provides several socio-economic benefits, improved food security and reduce post harvesting loss by allowing to longer storage of food after drying compared to food that hasn't been dried.

Solar drying is an important step in the food production process. The main argument for food drying is to preserve the food for longer periods of time. However, it is important to note that the process is not just concerned with the removal of moisture content from the food but also to maintain the quality of the products. In rural areas where farmers grow fruits and vegetables without proper food drying facilities, the farmers need to sell the food in the market shortly after harvesting. When food production is high, the farmers have to sell the food at low price to prevent the food from losing value through decomposition. Therefore, the solar food dryer might be able to prevent the financial losses farmers in these situations face. Dried food can be stored longer and retain quality longer. Moreover, dried fruits and vegetables might be sold as differentiated products which possibly enhances their market value.

Although it is difficult to establish the current status of the technology in terms of market penetration as data on this technology is insufficient. However, as the product can be locally manufactured and improve the food quality, with this characteristic enhances the market potential of this product.

Market Barriers for Solar Dryers:

Renewable energy technologies such as solar dryers face considerable barriers in market transactions which includes:

  •  Lack of Information: Beneficiaries may have insufficient information to make informed choices about the drying technologies.
  • Outreach of the Installers: Private companies involved in the promotion or manufacturing of such technologies are less able to communicate directly with large numbers of customers. Hence they have less likely penetration in the market and the customers too have limited information about the technology.
  • High Transaction Costs: Small private companies have high transaction costs at many stages of the development cycle which increase the cost of transaction.
  • High Financing Costs: In addition to having higher transaction costs, financial institutions are generally perceiving them as risky, so that they may lend money at higher rates. Financing costs can greatly affect the price and competitiveness of this technologies.
  • Absence of Appropriate Distribution Channels: As with any market product, this means that distribution channels and service networks should be established to ensure technology access and the continuity of operations. A key challenge for many suppliers is to establish a similar distribution channel and provide after sales service in the jurisdiction.

Business Models for Solar Dryers:

Various sectors including the government have put a strong emphasis on development of renewable energy development. However, solar dryers technologies are not being considered or treated with high importance compared to other Renewable Energy Technologies (RETs). In addition to that, in 2013 Nepal Rastra Bank (NRB’s) Unified Directives (2013)[2] were endorsed with the crucial step for motivating Bank and Financial Institution’s (BFIs) further involvement in this sector. The directives clearly state that the loans and advances, up to USD 600/beneficiary household, disbursed to micro-hydro installation with maximum 50 kW capacity, solar home system, solar cooker, solar dryer, solar pumps, biogas, improved water mills, improved cook stoves, and for wind energy installation will be counted as deprived sector lending. The BFIs can fulfill their respective deprived sector lending obligation through financing in this sector. But the BFIs are mostly focused on bigger technologies like Micro/Mini Hydropower and Urban Solar Home Systems rather than other smaller RE technologies.

Solar dryers are generally capital intensive and therefore the financial feasibility is the key compared with conventional drying practices. Continued use of the dryers for multiple products rather than seasonal use will decrease the drying cost and payback. The existing subsidy policy explicit creates the policy conditions for its promotion. The immediate aim is to focus on establishing a favorable environment for solar technology penetration in the country both in rural and urban areas.

Lack of information through traditional mediums in developing countries impedes the dissemination of valuable and even essential agricultural techniques. Because of this condition, successes are isolated and potential benefits delayed. It is necessary to move forward and implement solar dryers that have already been demonstrated.  Private vendors, in close collaboration with Government and Civil Society Organization need to work together in identifying the demand in the ground level and support the farmers in adopting the technologies.

The delivery model is a key determinant for how accessible solar dryers technologies can be reached to farmers, whether they are subsistence, smallholder or commercial. The initial upfront capital cost of such technologies (compared to traditional process) inhibits them to adapt the technologies. Financial support in form of capital subsidies provided by the GoN is provided to overcome the initial capital cost barrier that is associated with it. Uptake is often seen to remain limited despite capital subsidies being offered. This usually reflects a lack of financing options for the remainder of the capital cost. Capital subsidies, therefore, often need to be complemented by enhanced credit access. Since subsistence and smallholder farmers usually have constrained cash flows and hence the financing should be closely linked to the cropping seasons so that they are able to pay the loan timely.


A key component to developing the market for RETs such as solar dryers in rural areas is to raise awareness and demonstrate the viability and reliability of the technology. Furthermore, it is also essential to take into account and target the various stakeholders that cover the entire value chain, those involved in policy and programme formulation, design and installation of solar dryers and BFIs. Private vendors should ensure and establish distribution channel and provide after sales service in the jurisdiction for continue operation and maintenance of the systems. Such kind of technology can be locally manufactured and improve the food quality, which enhances the market potential of this product. Thus the technology can provide several socio-economic benefits, improved food security and reduce post harvesting loss and increased the income of the farmers. ---Bikash Uprety is a Technical Advisor at Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH

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