To measure efficiency of solar cell

In this post, practical performance for efficiency of solar cell is given here. The solar cell efficiency depends upon type of material for solar cell, solar irradiance, solar cell dimensions and mono facial or bi facial.

Solar cells generate electrical power by converting solar radiation into direct current electricity.

It is one of the fastest growing power-generation technologies in the world. The solar cell efficiency is the ratio of the electrical output of a solar cell to the incident energy in the form of sunlight. The energy conversion efficiency (η) of a solar cell is the percentage of the solar energy to which the cell is exposed that is converted into electrical energy. The solar cell efficiency is measured under standard test conditions at temperature of 25°C and an irradiance of 1000 W/m2 with an air mass 1.5 spectrum.

The efficiency of solar cell is calculated by following formula

η = { Power output (watt / m2) / Power input watt / m2 } × 100%

Power output = Vm × Im / Area


Vm = Maximum voltage (from I – V curve / Datasheet)

Im = Maximum current (from I – V curve / Datasheet)

A = Area of solar cell (meter2) = Length × Breath

Power input = 1000 W/m2 (Standard test conditions)

η = (______________ / 1000) × 100%

Observation Table

The following readings are noted from I – V characteristics of solar cell at specific irradiance of 1000 W/m2, lower than this value resulting decrease of efficiency.  

Maximum voltage Vm

Maximum current Im

Maximum Power

Pm = Vm × Im





Solar cell dimensions


Length in meter

Breath in meter

Area = Length × Breath






Monocrystalline Si Cell 50 Wp 36 cells

Im = 2.760 A

Vm = 18.10 V

Power = Im × Vm = 2.760 × 18.10 = 49.956 Watt

Area of solar panel = 670 mm × 540 mm

                               = 0.670 m × 0.540 m

                               = 0.3618 m2

Power output in watt / m2 = 49.956 / 0.3618 = 138.07

η = (138.07/ 1000) × 100% = 13.80%


The value of Im and Vm is taken from the I – V characteristics of solar cell. The performance of I – V characteristics of solar cell is performed at temperature of 25°C and an irradiance of 1000 W/m2. It is clearly visible from the below graph that the efficiency decreases for lower value of irradiation.


Efficiency of solar cell, performance of efficiency of solar cell, solar cell efficiency, solar cell efficiency practical, effect of irradiance on solar cell

( Data Source: PV Syst )

Solar Efficiency Questions

1. Define solar cell efficiency

The efficiency of solar cell refers to fraction of the input solar irradiance converted into electrical power.

      η = (Electrical Output Power × 100) / (Solar irradiance × Area)

2. Describe the effect of tilt angle on solar cell output.

The solar output power decreases for horizontal position of the solar cell. Keep the solar cell tilt angle as latitude of the site in order to receive optimum output from solar cell.

3. Which parameter greatly affects the efficiency of solar cell?

Solar irradiance, temperature of solar cell, reflection or albedo, solar cell or panel tilt angle

4. Can solar panels be 100% efficient?

No, the national renewable energy achieved the highest efficiency of solar cell in the standard lab conditions was 47.6% recorded in Jun 2022.

5. Which solar panels is more efficient, mono crystalline or polycrystalline?

Monocrystalline solar cells are more efficient than polycrystalline solar cell.

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