Solar panel efficiency defines the amount of sunlight that can be converted by the panel into usable electricity.

Solar panel efficiencies for a panel depends on the cell type, manufacturer and size of the panel. A list of solar panel efficiencies of top panel manufacturers based on cell type is given as follows:

Type of solar panel	Panel efficiency (%)*
Monocrystalline	17 – 21
Polycrystalline	14-16
Thin Film	7-14

It is worthwhile to note that the efficiencies mentioned above are for mass-produced panels. But a lot of manufacturers have managed to obtain greater efficiencies in research labs

A key point to be noted is that a solar panel of 1 MW with higher efficiency doesn’t generate more electricity than a 1 MW solar panel with a lower efficiency. In fact, regardless of the efficiency, a 1 MW solar panel generates the same amount of electricity. However, a high efficiency 1 MW solar panel requires less area than a 1 MW panel with a lower efficiency.

Solar panel efficiencies are provided under standard Testing Conditions (STC), which are listed below.

Standard Testing Conditions

Temperature	25ᵒC
Incoming solar radiation (Insolation)	1000W/m2
Air mass ratio (AM)	1.5

AM represents a coefficient that accounts for the scattering of light as it passes through the atmosphere, and changes in sun angle that in turn affect solar radiation.