This document summarizes key parameters of solar module performance curves (IV curves), including open circuit voltage (Voc), short circuit current (Isc), fill factor, efficiency, shunt and series resistance, temperature coefficients, and standard test conditions (STC). An IV curve provides information on module performance, resistance, design/manufacturing quality, and effects of connections. Voc depends on material properties and temperature while Isc depends on light intensity. Fill factor and efficiency indicate optimal power output. Shunt and series resistance should be low/high respectively to minimize power loss. STC are used as a standard reference point for measuring performance.

1. Solar Module IV Curve
Parameter's

2. Overview
IV Curve
Voc & Isc
Fill Factor
Efficiency
Shunt and Series Resistance
CTM Loss
STC Condition
Maximum system Voltage
Maximum Series fuse
Temperature Coefficients

3. IV Curve of Solar Cell
1. I-V curve gives information on: –
 Performance (Pmax, Voc, Isc, η and FF)
 Resistance of the PV-module (Rs and Rsh)
 Improper cell and module design
 Improper manufacturing
 Faulty module manufacturing
 Effect of parallel and series connections
 Non-uniform anti-reflective coating
 Possible micro-cracks and/or hotspots
 Loose wiring in junction box

4. Open Circuit Voltage (Voc)
 The Voc is the Maximum Voltage From a solar cell and this
occurs Zero Current.
 Voc depends on: –
 Band gap of semiconductor
 Amount of doping of P&N layers
 Material purity
 Light generated current.
 Temperature of the PV-module

5. Short Circuit Current (Isc)
 The short-circuit current is the current through the solar
cell when the voltage across the solar cell is zero
 Isc depends on:
 Spectrum of light source
 Optical properties of the PV module (light absorption)
 Number of photons (i.e. power of light source/ intensity)
 Area of PV module

6. Efficiency Of Solar Module
 The Efficiency is most commonly used
parameter to compare the performance
of one PV-module with the other.
 Ratio of energy output from the PV-
module (Pmax) to input from the sun (Pin)
 η = Pmax / Pin Or Module Wattage/Area

7. Shunt Resistance
 Low shunt resistance provides an alternate
current path.
 This reduces the amount of current flowing
through the solar cell and reduces the voltage.
 Shunt resistance should be high.
 • Effect is bigger at low light levels: –
 Less light generated current, I
 impact of loss is larger. –
 When cell has lower voltage, the impact of
resistance in parallel is large.

8. Series Resistance
Series resistance should be as low as possible.
 Or Else there will be Poor conduction
 These May Occur Due to Three causes, mainly poor solar cell
design
 The movement of current through the emitter and base of the
solar cell
 The contact resistance between the metal contact and the
silicon.
 The resistance of the top and rear metal contacts.

9. CTM Loss
 CTM Loss= ((Cell wattage * No of Cell-
Produced wattage)/(Cell wattage * No
of Cell))*100
 Losses May occur due to
 EVA Used
 Busbar Used
 TCI (Tin Copper Interconnector
 Glass Used
 Junction Box Used
 Distance Between Cells , String and
Frames.

10. Fill Factor (FF)
Fill Factor is the ratio of the maximum power from the solar cell to
the product of Voc and Isc.
 The short-circuit current and the open-circuit voltage are the
maximum current and voltage respectively from a solar cell
 Formula for Calculating the Fill Factor is
 FF= ((Vmp x*Imp)/(Voc * Isc)) *100
 Fill Factor Depends Upon Series And Shunt Resistance
 If The Module Is Having Fill Factor of 70 t0 80% then Module Is
Considered as a Class A Quality Module

11. Standard Test Condition For Testing the Solar Panel
are as Follows
 Temperature, ie 25C
 Irradiance/Light intensity, Ie 1000W/M
 Air Mass, Ie 1.5 ie
When The Sun is exactly Perpendicular at that time
intensity will be high and when sun is at a Slant
position at that time Intensity will be 1000
It Is Calculated by AM = 1/Cos or Shadow
height/Width
STC Condition

12.  Maximum System Voltage is is dependent upon the Some of the Factors
 type of the junction box and Diode Used.
 Type of Back sheet used
 Spacing between frame, cell, string, busbar.
For Ex if the system voltage is 1000v then number of panels connected in series should be 20
i.e.. 1000v/ Open Circuit Voltage.
 If The System Voltage Is Changed Means then There will be some Changes in
modules
• Change Of Junction Box
• Type of backsheet Used
• Gap between Cells, busbar, Frame need to be Changed.
Maximum System Voltage

13. Isc of a PV Panel will be around 10A
 To calculate the maximum source circuit current, requires you to multiply the rated
Isc value by 125%
 If ithe isc is 10A then 10*1.25=12.5A
 The maximum fuse rating of a diode is 15A
Maximum Series Fuse

14.  All solar cells have a temperature coefficient. As a solar panel increases in temperature, the power output of the solar
panel decreases. Generally, monocrystalline solar cells have a temperature coefficient of -0.5%/degC(Depending of
Manufacturers).This means a mono solar panel will lose half of one percent of its power for every degree the
temperature rises. Solar panels are all rated at 25degC, however, when solar panels are installed on a roof, they
generally reach much higher temperatures
 Lets say a 250W monocrystalline solar panel installed on a roof is at 65degC.
The solar panel’s power loss can be calculated as follows:
65degC – 25degC = 40degC
40degC x -0.5% = 20%
Therefore panel power loss = 20% x 250W = 50W
Therefore panel power = 200W
Temperature Coefficients

15. Thank you