KLP S-Series Solar Emulator

In a single 1U package, the KEPCO KLP S-series is capable of emulating a wide variety of solar cells, eliminating the costly and time-consuming process of securing characterization samples. It further saves the necessity of purchasing a variable light source for emulation of illumination conditions.

The KLP S-series is an indispensable tool in the testing and characterization of power inverters. With its scalability, flexibility and speed, the S-series will enable your products to get to market quickly, with the performance you need and all at a very affordable price.

BACKGROUND. Solar cells and solar panels are typically connected to the electrical grid via an inverter which operates at the Pmp (Maximum power point). Power inverters monitor the current and voltage (hence power) that the inverter draws from the solar cell. By varying its duty cycle, the inverter changes its operating point and re-computes the new power point. Continuing in this fashion the inverter increases and decreases the duty cycle until it finds the maximum power point. The inverter repeats this process continually so that it maintains operation at the Pmp, even when there are varying illumination conditions - cloud coverage, angle of sun, etc. The output of the solar cell is typically depicted by an I-V curve. This curve depends on four variables:

• Voc - Voltage Open Collector - The voltage of the cell when no current is drawn (maximum voltage).
• Isc - Current Short Circuit - The current from the cell when the output of the cell is short-circuited (maximum current).
• Vmp - Voltage Maximum Power - The cell voltage at the maximum power point.
• Imp - Current Maximum Power - The cell current at the maximum power point.

Kepco's KLP S-series emulates the solar cell by inserting the values for Voc, Isc, Vmp and Imp into emulation equations that replicate the unique I-V curve as shown in Figure 1. The KLP then emulates solar cell behavior by supplying the appropriate output voltage for each value of current drawn by the inverter. It does this dynamically as the inverter searches for the Maximum Power point Pmp. By changing Voc, Isc, Vmp and Imp it is possible to emulate different illumination conditions for the same cell or the characteristics of a completely different cell or panel.

Figure 1 - Typical Solar Emulator I-V Curve

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