John has used a solar simulator setup to measure the relation between the voltage and the current of a small photovoltaic module (40 cm long and 40 cm wide). The measurement setup maintains the standard measurement conditions: the temperature is controlled to 25oC, the incident spectrum is the AM1.5 spectrum and the incident power density is 1000W/m2.
John decides to connect two of these modules with a cable in series. This results in an additional 2 milli-ohms; series resistance loss. What is the new fill factor (in %)? (Hint: use the voltage drop at the maximum power point).
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To calculate the new fill factor, we need to first understand what the fill factor represents.
The fill factor (FF) is a key parameter used to characterize the performance of a photovoltaic module. It is defined as the ratio of the maximum power output of the module (Pmax) to the product of the open-circuit voltage (Voc) and the short-circuit current (Isc) of the module.
Fill Factor (FF) = Pmax / (Voc * Isc)
In this case, we are connecting two modules in series, which adds an additional 2 milli-ohms of series resistance loss. This resistance will cause a voltage drop at the maximum power point (MPP), which we can use to calculate the new fill factor.
To calculate the new fill factor, follow these steps:
1. Determine the voltage drop at the MPP caused by the additional series resistance. Let's assume this voltage drop is represented by deltaV.
- The voltage drop can be calculated by multiplying the current at the MPP (denoted as Imp) by the additional series resistance (2 milli-ohms).
deltaV = Imp * 2 milli-ohms
2. Subtract the voltage drop from the original Voc to obtain the new Voc.
- Let's assume the original Voc is denoted as Voc_orig.
Voc_new = Voc_orig - deltaV
3. Calculate the new fill factor using the new Voc, the original Isc, and the maximum power point voltage (denoted as Vmpp_orig) and maximum power point current (denoted as Pmpp_orig).
- FF_new = Pmpp_orig / (Voc_new * Isc_orig)
Remember, you'll need the values of Voc_orig, Isc_orig, Pmpp_orig, and the current at the maximum power point (Imp) to perform the calculations. These values can be obtained from the measurements or specifications provided by John.
By following these steps and using the given voltage drop, you can calculate the new fill factor as a percentage.