Photovoltaic modules technical specifications explained

Written By: nuvision Published In: The Module Toolbox Created Date: 2015-03-04 Hits: 3620

An overview of what the various PV Module Technical Specifications mean and how they are applied to sizing a PV system.

Electrical Specification

Nominal Power Rating 

 The amount of energy the panel will generate under standard test conditions (STC)
Power Tolerance  The power output of each panel manufactured varies slightly. The power tolerance tell you how much the power output of a panel is allowed to vary from the nominal power rating 
Module Efficiency  The Module Efficiency is the percentage of light energy falling on the module area whch can be convetrted into electricity 
Voltage at Pmax This is the electrical voltage of the panel, when the system is generating optimally under standard test conditions 
Current at Pmax This is the electrical current produced by the panel, when the system is generating optimally under standard test conditions.
Pmax  'Maximum power' is achieved when the inverter is working optimally and drawing the maximum power it can from the panels.
Open Circuit Voltage  This is the electrical current produced by the panelif it leads are short-circuited. THis is the highest current that the panel can produce under standard conditions (STC)
Short-circuit current  This is the electrcal current produced by the panel if its leads are short circuited. This is the highest current the panel can produce under standard conditions 
Standard Test Conditions (STC)

The standard lab condtions under wwhcih modules are tested:

The parameters are 

  • Irradience = 1000W/2
  • 25°C temperature 
  • AM1.5 spectrum
Maximum system voltage  This is the maximum voltage that the panel can withstand. When designning a system you should check that the string will always be below the maximum system voltage

Temperature Coefficient

Nominal operating cell temperature The voltage, current and power generated is affected by temperature variances. They can be calculated using thermal coefficients. The Nominal Operating Cell Temperature, typically 45°C, is used as a reference point for this calculation
Temperature coefficient of Pmax Modules generate less power at higher temperatures. The temperature coefficient of Pmax tells you how the maximum output from the panel varies with temperature
Temperature coefficient of VOC  The voltage of a panel drops as temperature increases. The temperature coefficient of VOC tells you hoow the voltage (specifically the open circuit voltage) varies with temperature  
Temperature coefficient of ISC  The current produced by a panel increases with temperature. The temperature coefficient of ISC tells you how the current  (specifically the short circuit current) varies with temperature

Mechanical Data 

No of cells  Each module is made up of a number of cells typically 60 or 72 
Connectors  Most modules use MC4s but some use the Tyco or MC3 connectors 
Junction Box  The IP rating is usually given for the sealing of the Junction Box 

*IP Rating (International Protection Marking) is a rating system which rates the degree of protection provided against intrusion such as dust, water by mechanical casings and electrical enclosures. 

 

Tags: Solar Energy Photvoltaic PV Module