October 25, 2002ENO Presentation1 Frederick M. Ishengoma Dept. of Electrical Power Eng. NTNU Stand-alone PV power supply for developing countries

October 25, 2002ENO Presentation2 Access to Grid electricity  Estimated 2 billion people across the world don't have access to electricity  Majority of these are in the developing countries especially in rural remote areas

October 25, 2002ENO Presentation3 Access to Grid electricity  Southern Africa: About 21.74% of population have access to electricity in their homes particularly in urban areas (40million/184 million)  In rural remote areas, population is dispersed, has low incomes and the grid power supply is not fully extended to these areas due to viability and financial constraints ?fuelwood, candles, kerosine, dry-cell batteries, diesel generators, etc. are used to meet energy needs

October 25, 2002ENO Presentation4 Push for Renewable energy  Potential threat of global climate change  Increasing energy demand world-wide  Uncertainty of non-renewable energy (price and availability)  World energy policy on using clean (non-polluting source of energy)

October 25, 2002ENO Presentation5 Photovoltaic (PV)  Photovoltaic – Generation of electricity from the sun using solar cells  Reliable and economical power source in rural remote areas

October 25, 2002ENO Presentation6 Advantages of PV ?Non-polluting: No fuel burning ?Availability ?Reliability: Service time of at least 20 years ?Low operating costs: The fuel is free. With no moving parts, the cells require little upkeep. ?Modularity: Portability and sizebility  Low Construction Costs: PV systems are placed close to where the electricity is used, hence shorter and few wires, shorter construction time

October 25, 2002ENO Presentation7 Disadvantages of PV  High initial capital cost  Very low PV cell conversion efficiency (efficiency of solar modules differs depending on the materials used) ?R&D ->development of low-cost PV materials (less $/W p ) and cost reduction in BOS components production of modules with higher efficiencies (about 30%).

October 25, 2002ENO Presentation8 PV costs and production trend

October 25, 2002ENO Presentation9 Solar energy  Most of dev. Countries have abundance of the solar energy resource all year round  PV for RAPS, telecommunication, water pumping, etc.  Solar water heating (SWH): hot water supply (domestic, commercial and industrial use)

October 25, 2002ENO Presentation10

October 25, 2002ENO Presentation11 Barriers to PV Usage  Slow pace of power sector liberalisation and privatisation =>Independent Power Producers  Low levels of industrial development ( delivery time and expensive due to transport, maintenance, labour costs).  Hardware from Europe, SA, Germany, USA  Lack of renewable energy policies  Lack of training and capacity building initiatives  Courses which provide exposure to energy technology ->renewable energy engineers and technicians

October 25, 2002ENO Presentation12 Types of PV systems  Grid connected PV power system ?Fastest growing applications in developed countries  Stand-alone PV power supply (SAPS) or Remote Area PV Power Supply (RAPS)

October 25, 2002ENO Presentation13 Grid connected PV system

October 25, 2002ENO Presentation14 Hybrid system

October 25, 2002ENO Presentation15 Stand-alone PV system Sun

October 25, 2002ENO Presentation16 Main areas of PV research  Optimization of solar cells  Optimization of solar power conversion ?Power electronics and control algorithms in the PV conversion process (efficiency of DC-DC converters, efficiency of inverters, improvement in battery charging mechanism, etc.)

October 25, 2002ENO Presentation17 Model of PV cell (module)

October 25, 2002ENO Presentation18 I-V and P-V characteristics

October 25, 2002ENO Presentation19 I-V and P-V characteristics - constant solar cell temperat.

October 25, 2002ENO Presentation20 I-V and P-V characteristics - constant Irradiance

October 25, 2002ENO Presentation21 Maximum Power Point Tracker (MPPT) MPP

October 25, 2002ENO Presentation22 Control Sun

October 25, 2002ENO Presentation23 Advantages of digital Control  Flexibility due to programmability ?Modification of control algorithms and performing complex tasks which are impossible using analog circuitry ?Modifications to the design are made through code changes, not component changes  Reduces components of the system (cost and weight)

October 25, 2002ENO Presentation24 Main tasks  Mathematical Models for a PV module to be used in Matlab/simulink for MPPT and battery charging  Interface board for signals required for control  MPPT algorithm  Four states battery charging algorithm (trickle, bulk, overcharge and float states) with temperature compensation)  Control algorithm for inverter for linear and non- linear loads and dimensioning of LC filter for inverter  Extra: PECCTerm development and logging function

October 25, 2002ENO Presentation25 Conclusion  The cost of PV energy technologies is on a falling trend and is expected to fall further as demand and production increases  PV technology will serve rural areas population in developing countries from costs incurred in using costly energy sources and will improve their social and economical life  Locally produced hardware and local experts will ensure availability of service and maintenance and increase confidence in PV usage