A Solar Powered Vaccine Refrigerator System
Microcontroller Provides Improved Performance
Technologies used


Industrial sector (PRODCOM code)
    29 Non-Domestic Cooling and Ventilation Equipment
    322 Remote Telecommunications Equipment
    331 Medical and Surgical Equipment and Orthopaedic Appliances
    332 Instruments and Appliances for Measuring, Checking, Testing etc

Dulas Ltd. is a small company of 22 people that has specialised for 15 years in the development, production and installation of equipment based on renewable energy resources. The company is well established in the solar, hydro and wind electricity generation industries (Prodcom sector 40), and these activities generate sales of 2 M Euro per annum. The company's markets its products and services on a worldwide basis, and has sales in Europe, Africa, South America, and India.

Dulas Ltd specialises in products and consultancy services in all areas of renewable energy. The company sells its products and services on a world wide basis, and has sales in Europe, Africa, India, and South America. The company's product and services include turnkey hydroelectric generation systems (1 kW to 500 kW), remote solar powered systems, including healthcare and telecommunication systems, and bio-mass energy production systems, including wood burners on a commercial scale. In addition consultancy activity in the area of environmental policy and planning consultancy for wind farms, and research into new application areas for renewable energy sources is conducted.

Sales of the company's solar powered systems represent approximately 50% of the company's turnover. One of the company's products is a solar powered vaccine refrigeration unit for application in delivering inoculation services in third world countries where mains power supplies are unreliable or non- existent.

The objective of this application experiment was to increase the functionality and to reduce the manufacturing costs of the company's photo voltaic battery charger control system used in the solar powered refrigerator by the use of microcontroller device technology. The control system is based entirely on discrete analogue device technology.

The introduction of a microcontroller allowing the provision of clearer status displays will provide enhanced user confidence as to the performance of the system, resulting in a much more reliable refrigeration system design. The main fault mechanism with the current controller system is that associated with the user adjusting or rewiring the controller installation through a lack of visibility or confidence in the status of the charging system. This will provide a marketing advantage for the company in the sale of its Solar Powered Refrigerators.

The improved functionality provided by the incorporation of microcontroller technology includes:

  • Improved battery charging regimes, including three step charging methods.
  • Improved and simpler field set up procedures and adjustments for the user and installation engineer.
  • Numeric or bar graph display options to provide the user with information as to the status of the Battery Voltage, Charge and Discharge current, and the SOC (state of charge) in terms of % capacity left in battery.
  • More accurate determination of the battery State Of Charge using a calculation of the battery input and output currents over time, with periodic re-calibration provided by the use of the more accurate measurement and computational capabilities.
  • The long term recording of system performance, enabling the patterns of usage in certain applications to be monitored and more effective control strategies to be employed.

In addition, the inherent flexibility of the implementation provides the following benefits of applicability to other PV opportunities available to the company, and applicability to lower volume, non-standard PV charging applications and other charging control systems (for example, wind power). This has already resulted in the application of the technology in one product, a PV powered lantern.

The application experiment was completed in 11 months at a cost of 27 K Euro. The expected payback period for this development cost is 19 months. The ROI (return on investment) over the anticipates 3 year life of the product is estimated to be 681% based on the 27 K Euro prototype development costs.

The industrialisation costs for the improved refrigerator control system is 35 K Euro; these costs include the redesign of the refrigerator to incorporate the new control unit.


    Dulas Ltd,
    Dyfi Eco Parc,
    SY20 8AX
    United Kingdom.

Detailed information

You can also benefit from microelectronics

Microcontroller technology provided Dulas Ltd. with the means of improving its products and enhancing its market position. You can also achieve significant benefits by acquiring the right microelectronics technology and utilising it in your product or manufacturing process. You can get help from FUSE to realise this.

FUSE is a technology transfer programme, funded by the European Commission to stimulate the wider use of microelectronics technologies by European enterprises to increase their competitiveness and enhance their economic growth. The demonstrator described here is one of many examples in the public FUSE portfolio covering the whole spectrum of microelectronics technologies and spanning a wide range of applications and industry sectors.

FUSE provides you with:

  • Best practice in acquiring specific microelectronics technologies and conducting full development projects through the FUSE portfolio of real life demonstrator documents.
  • Local training and expert support to plan your innovation realistically and help you conduct your project successfully.

Further information and support relating to this and other demonstrators can be obtained from the addresses below.

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For further information and support regarding this case study, please contact a Technology Transfer Node (TTN) in your region.
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Univercity of Glamorgan
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