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Olpc Apr 4 2010


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Solar charger/regulator options to improve efficiency of solar panel output

Published in: Technology

Olpc Apr 4 2010

  1. 1. Low-Cost Solar Charge Controller with Maximum Power Point Tracking for the Developing World Robert Pilawa OLPC Presentation April 4th, 2010
  2. 2. Outline • Charge Controller Basics • Maximum Power Point Tracking • Cost considerations • Our prototype
  3. 3. Charge Controller Basics • Protect battery from over-voltage • Protect battery from under-voltage • Low-cost • Used for low-power applications
  4. 4. Maximum power point problem • Typical 12V panel, Vmp=17 V • Mismatch between panel voltage and battery voltage • Does not extract maximum available power from panel • Think of it as gears on a motor
  5. 5. Maximum power point tracker • Smart power electronics adjust panel voltage to extract maximum power • Typically more expensive
  6. 6. Cost consideration • MPPT can capture as much as 30% more of the available power. • Typically not used for low (<50W) panels • With 20% increase in power, you should use it if additional cost is $0.80/Watt higher than simple charge controller (for $4/Watt panels) • So a 30W MPPT charger would be considered if it costs $24 more than a simple charger • Today's designs cost > $1/Watt
  7. 7. Our low-cost solar charger • Targeting $0.25/Watt • Uses innovative new digital control • Low-cost power electronics components • Robust implementation • Able to charge lead-acid batteries, cell-phones, and OLPC X0 • Expected first prototypes for testing early summer of 2010