Techno-Guide on Multi-Commodity Solar Tunnel Dryer (MCSTD)

The Philippines commonly practices sundrying techniques in drying products. However, the process is largely dependent on the weather and is very difficult during the rainy season. Moreover, the traditional method usually yields products with high microbial load. The exposure to wind and weather is a relatively slow process and results to a great loss through spoilage, lack of uniformity in the final product and development of undesirable flavor.

The sundrying practice of small-scale producers diminishes the quality of the commodities being dried. The practice allows dust, flies and microorganisms to feast on the products. Aside from its health hazards, the poor quality dried products fail quality standards and are unacceptable for export. Worse, many small-scale processors hardly meet the operation cost of commercial mechanical dryers.

To help solve this problem, the Multi-Commodity Solar Tunnel Dryer (MCSTD) technology was adapted by BPRE as a viable alternative to sundrying and use of commercial mechanical dryers. This dryer is a modified version of the solar tunnel dryer developed by the researchers of the Hohenheim University in Germany.


  1. Cheaper in investment and operation cost than other available commercial mechanical dryers;
  2. Dries commodities simultaneously, efficiently and hygienically;
  3. Preserves the quality of dried products longer because of lesser microbial contamination;
  4. Allows ready supply of agricultural products even during lean months;
  5. Uses locally available materials to suit the needs of farmers and fisherfolks engaged in processing;
  6. Easy to install/dismantle and maintain; convenient to use and gender friendly.

Drying Performance

Aside from providing better quality dried products, the drying performance of MCSTD is significantly better than the traditional sundrying methods in terms of shorter drying time.

Commodity = Drying Time (8-hour Operation)

  • Tomato = 3-4 days
  • Tamarind = 3-4 days
  • Karamay = 1 day
  • Kamias = 2 days
  • Mushroom = 1 day
  • Tilapia fish = 1-1.5 days

Drying Components

BPRE’s MCSTD has three major components:heat collector, drying chamber and fan/blower. The heat collector and drying chamber are covered with UV-stablized polyethylene plastic sheets, mounted in inverted “V” metal frames. Installed inside the drying chamber is a 2-inch square wire mesh made of 4 mm iron bars. The trays containing the product are placed on top of this mesh.

An axial fan with electric motor forces air into the heat collector which increases the drying air temperature to 45°C to 60 °C.


BPRE’s MCSTD is fabricated using locally available construction materials. The modular design allows easy transport and installation in the processing areas.

  • Commodities: Mango, fish, seaweed and other perishable crops
  • Construction Materials: For heat collector and drying bed, use marine plywood, styropor, G.I. pipe, and plastic sheet
  • Blower: 1.0-1.25 m/sec 220 V, single phase
  • Dimension:
    • Heat collector, L=24ft, W=8ft
    • Drying bed, L=32ft, W=8ft
    • Axial fan, 88 watts, 220 V
  • Capacity: Maximum of 250 kg of mango slices
  • Investment cost: P100,000

Return on Investment

Financial analysis revealed that if MCSTD is acquired through facility loan payable in 5 years at 14% annual interest rate, the enterprise will be profitable. The investment can be recovered within 3 years and 2 months. An investment spread of 3.10% is realized when the discount rate (14%) is deducted from the calculated IRR. The net present value is still positive and the benefit cost ratio is slightly above the cut-off rate. The return on investment is 34.75%.

The table below shows the financial analysis of using MCSTD acquired through facility loan.

Financial Indicators = MCSTD Acquired Through Facility Loan

  • Payback Period = 3.17 years
  • Internal Rate of Return = 17.10%
  • Net Present Value = P33,172.45
  • Benefit Cost Ratio = 1.07
  • Return on Investment = 34.75%

For more information, contact:

The Executive Director
BPRE, CLSU Cmpd., Science City of Munoz, Nueva Ecija
Tel. No. (044)456-0213, 456-0282, 456-0287
Fax No. (044)456-0110
E-mail: [email protected] Website:

BPRE Liaison Office, 3rd Fir., ATI Bldg.
Elliptical Rd., Diliman, Quezon City
Tel. No. (02) 927-4019, 927-4029

Reference: Martinez, H.F., Apaga, A.R.M., Hipolito, A.V., Adoption of MCSTD by Small Scale Entrepreneur: The Case of the Kababaihang Masigia ng Nueva Ecija (KMNE). A paper presented during the 29th Agency in-house Research and Development Review on April 29-30, 2008 at BPRE, Science City of Munoz, Nueva Ecija, photo from


  1. By Christian N. Onia


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