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# Understanding the parameters in a Solar Panel Data Sheet. Solar Panels are one of the most significant components in a Solar PV System. Our choice of product is, therefore, very crucial.

This article explains how to read and understand the most relevant terms in a Solar Panel datasheet, to make a more informed decision while choosing the brand of Solar Module.

The Datasheet would contain details like the Manufacturer name, The Highlights of the panel, the capacity of panels available, the type of Panel(Poly or Mono), the warranty terms.

The Mechanical data section, shows the type of cell, the product dimension, the weight, and the other components that make up the panel.

The standard dimensions of most panels available in the market are approximately 2 meters by 1 meter.

The STC Parameters- The nominal power of the solar panel is measured under Standard Test Conditions(STC), i.e., at an irradiance of 1000W/m², cell temperature of 25°, and air mass of AM=1,5. These are standard test conditions.

The actual performance of the solar panel would vary significantly compared to its performance in Lab conditions.

Now let us look at the variables-

Vmpp- Voltage at Maximum Power Point

The Vmpp is the voltage at which the solar panel generates the highest power output. It is the actual voltage that the panel should read when connected to an inverter under standard test conditions.

Impp- Current at Maximum Power Point

The Impp is the number of Amperes delivered by the module at its maximum power point. It is the actual amperage the panel should read when connected to solar equipment under standard test conditions.

Voc-Open Circuit Voltage

Open circuit voltage is the number of volts the solar panel generates with no load across it (in an open circuit). It is obtained by measuring with a voltmeter across the positive and negative terminals. Since no load is connected to the panel, the current is not produced. The Voc is a very important parameter, as it determines the number of solar panels you can connect in series.

Isc-Short Circuit Current

Short Circuit Current is the amount of current solar panels output when not connected to a load. It is measured by creating a short circuit between the positive and negative leads. When determining how many amperes a connected device such as an inverter or a solar charger can withstand, the Isc is used. It is generally multiplied by 1.25 for safety requirements.

Module Efficiency

Panel efficiency is the total amount of solar energy that can be converted into actual electricity by a solar panel, under standard test conditions. A more efficient panel takes up slightly less space to produce an equal amount of power than a less efficient one.

The NOCT(Nominal Operating Cell Temperature) Parameters- The NOCT values are closer to actual site conditions, therefore depict more realistic values. These are measured at irradiation of 800 W/m², cell temperature of 20°, and AM=1,5.

Temperature Ratings- Temperature coefficient of Pmax

The maximum power output of a solar panel is inversely proportional to its temperature i.e.; power output decreases with an increase in temperature. The temperature coefficient of Pmax (maximum power), is a value that denotes the percentage change in power output per increase in temperature (%/°C). A temperature coefficient of Pmax of -0.39%/ °C means that the maximum power output of the photovoltaic module would decrease by 0.39% for every degree rise in temperature.