The irradiance uniformity over the work area is the most difficult Class AAA requirement to achieve and maintain. Hot spots can lead to significant errors in measured cell efficiency and can cause inaccurate binning of cells. The Class AAA spatial non-uniformity performance standard is designed to minimize the impact of hot spots and has a very stringent requirement of ≤2%. The plot shows the uniformity of the irradiance across a typical 2 x 2 in. simulator working area. Each unit will come with a plot of irradiance non-uniformity. The working distance ranges for each simulator are shown below.