Photovoltaic Power and Maximum Power Point Tracking (MPPT)

Voltage, Current, and Power in Photovoltaics

• The relationship between voltage and current (IV curve) in photovoltaics demonstrates that:
  • Voltage generation requires relatively little light.
  • Generating usable circuit current requires a significant amount of light to move electrons.
• Power is the relationship between flowing current and the pressure (voltage) moving that current.
  • Power = Voltage \times Current
• Maximum Power Point:
  • On the IV curve, there is a point at which maximum power is achieved.
  • This represents the most power a solar panel or string of panels can output at a given time.

Maximum Power Point Tracking (MPPT)

• MPPT is a technique used by tracking systems and inverters to maximize power extraction from photovoltaics.
  • It optimizes power output based on real-time conditions, rather than strictly following the sun's position.

Sun Tracking vs. MPPT

• Sun Tracking:
  • Relies on the predictable, linear path of the sun.
  • Tracking systems can be programmed to align panels with the sun's position at any time of day or year (e.g., May 9th at 1:15 PM).
  • However, this alignment may not always yield the maximum power output due to factors like cloud cover or reflective surfaces.
• Maximum Power Point Tracking (MPPT):
  • Instead of directly tracking the sun, MPPT systems monitor the power output of the solar panels.
  • Panels may be adjusted slightly away from the direct angle of the sun to achieve the highest possible power output.
  • MPPT optimizes power output by responding to dynamic environmental conditions.
• In essence, MPPT prioritizes the optimization of power output over the sun's exact location.