IES test vs Lux test

A customer recently asked us to provide a lux test report for a solar street light.

Their reference product measured 52 lux at an 8 m mounting height, while our product measured 48 lux.

At first, it seems like a simple comparison. But a single lux value only tells us the illuminance at a specific measurement point under specific test conditions. So without controlling the testing conditions, comparing these two numbers alone may not be objective enough.

A photometric test can provide much more information.

An IES file can contain the lamp's photometric data, including its light intensity distribution in different directions. This data can then be used in lighting software to simulate different mounting heights, pole spacings, road widths and installation angles.

So instead of asking only, “How many lux does this lamp produce?”, we can also look at the beam angle, LED module size, light distribution, mounting height, and other factors that affect the final lighting performance.

For road lighting projects, this broader information can be much more useful than a single lux measurement.