Photovoltaic panels in practice lesson
The lesson was carried out by an electrical specialist ? teacher in Zespół Szkół Elektrycznych in Włocławek Jacek Kandyba. It is the first part of the vocational training classes prepared as a result of the availability of the equipment such as PV cells kit bought in the Project ?Alternative Energy ? present and future energetic? for its realization.
The lesson took place on the 23^{rd} May 2014. It lasted 90 minutes and was aimed at both Hungarian and Polish students during the stay of the Hungarian students in Poland.
Pointing at Maximum Power for PV
Summary
Student teams measure voltage and current in order to determine the power output of a photovoltaic (PV) panel. They change the resistance in a simple circuit connected to the panel to demonstrate the effects on voltage, current, and power output. After collecting data, they calculate power for each resistance setting, creating a graph of current vs. voltage, and indentifying the maximum power point.
Photovoltaic (PV) panels utilize a scientific technology that creates power from solar radiation. Because PV panels are expensive and their power production is limited by the amount of sunlight available, it is important for them to run as efficiently as possible. One way to improve PV panel efficiency is to adjust the resistance in the design of the electrical circuit to create a combination of voltage and current that results in the greatest power output. Engineers must understand how to control a basic circuit in order to design PV arrays that operate as efficiently as possible.
PreReq Knowledge
A basic understanding of an electrical circuit, including voltage, current, power and resistance.
Learning Objectives
After this activity, students should be able to:
 Measure the voltage and current of a photovoltaic (PV) electrical circuit.
 Explain how to calculate and maximize the DC power output of a PV system.
Materials List
Each group needs:
 PV panel 5Wp
 wires
 multimeters (voltmeter, ammeter) and light meter lux
 decade resistor
 sunlight, or a lamp
Equations
Ohm's law: V=I*R
Electrical power equation: P=V*I
Where :
V = potential difference (in volts V)
I = current (in amperes A)
R = resistance (in Ohms ?)
P = power (in watts W)
Definitions
maximum power point (MPP): 
The point on a power (IV) curve that has the highest value of the product of its corresponding voltage and current, or the highest power output. 
Materials List
The experiment can be conducted either outdoors in sunlight, or indoors using a 500watt incandescent lamp. Simply place the PV panel under the lamp. This lamp can become extremely hot! Be careful! While conducting the experiment, make sure nothing blocks the light from reaching the panel. Try not to modify the position or any other variables that might disrupt the results.
Circuit diagram for measurement PV panel
Figure 1. The electrical circuit configuration to measure voltage and current.
Experiment Procedure
 assemble the circuit (Figure 1)
 measure the illumination
 measure the voltage open circuit Voc
 measure the shortcircuit current Isc
 change the resistance of the resistor decade box
 measure the voltage and current
 write the results in the table 1
Mono Solar panel PV specifications:
Type  RSM 5W 

Nominal Maximum Power(Pmax) 
5W 
Optimum operating voltage (Vmpp) 
12V 
Optimum operating current (Impp) 
0.25A 
Opencircuit voltage (Voc) 
21,9V 
Shortcircuit current (Isc) 
0.315A 
Power tolerance 
?2% 
Maximum system voltage 
1000V(IEC)/600V(UL) 
Maximum Serises Fuse Rating 
15A 
NOCT 
45 °c 
Temperature Coefficient PMAX 
0.43%/ °c 
Temperature Coefficient Voc 
0.34%/ °c 
Standard STCs: 1000 W/m2 solar irradiance, 1.5 Air Mass AM, temperature of 25^{o}C. 
Table 1: PV Panel Data Collection
light intensity [lx] ???????? 

Trial # 
Collected Data 
Calculated 

Resistance [W] 
Voltage [V] 
Current [A] 
Power [W] 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 
PostExperiment Assignment
 calculate power (voltage * current) for each reading and record it in the table.
 graph current and power vs. voltage on the graph provided
I=f(U)
Figure 2. Current and Voltage Curves
P=f(U)
Figure 3. Power Curves