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.
