1. EPTiF

Products and Services
Photovoltaic Systems Related Products

On-site EL/PL Inspection Machine "EPTiF"

"EPTiF (EL/PL Test in Field)" enables you to check invisible conditions of an installed photovoltaic (PV) panels during daytime by EL and PL inspections, which are adopted by a number of PV panel manufacturers, without detaching PV panels. Irradiance-independent and steady results can be obtained. This is the first in the industry.

On-site EL/PL Inspection Machine
See EPTiF video and how actual PV panels are inspected at a PV plant.
Rakit video on YouTube(1 min. 45 sec. subtitle: Japanese)
  • Developed by Institute for Photovoltaics, University of Stuttgart
  • Provided by Solarzentrum Stuttgart GmbH

Features of EPTiF

  • Quality inspection adopted by panel manufacturers available on site without detaching panels
  • EL and PL inspections available on site without a dark room facility or a laser light source
  • Inspects under almost all sunlight conditions from cloudy to sunny weather
  • Displays the results with clear images
  • Automatically detects defects by our original image analysis
  • Inspects every type of PV system from residential to utility-scale
  • Detects even signs of defects
  • Prevents or immediately stops power loss or accidents caused by defects
  • Indoor and outdoor inspections available such as acceptance test before installation, panel inspection during completion inspection, etc.
  • Suitable for investigations on power loss, inspections after typhoon, heavy snow, etc.

Inspection Principle of EPTiF

Principle of EL Inspection

Electric current is applied to PV panels so that they will emit light at a certain frequency. The emitted light is captured by IR camera and then visualized.
If there are any defects in crystals or electrodes, luminescence intensity decreases. This phenomenon is utilized for imaging invible defects such as degradation caused by PID, cracks, etc.

Principle of PL Inspection

PV panels generate electric power and at the same time emit light after absorbing light. In PL inspection, laser light is irradiated onto PV cells and the emitted light is captured to evaluate degradation or homogeneity of cells.

EL images

EPTiF System Configuration

EPTiF comprises of signal input box, camera, and PC.
Unlike the conventional EL inspection method, EPTiF inputs a specifically modulated power signals into the panels (string). The camera then locks onto the input signals and extracts them from the background radiation, thus calculating the luminescence image. Therefore, it requires no dark room facility. In PL inspection, it uses sunlight as a light source so that no laser is required. Also, inspection by panels or strings is possible, not only by cells.

Inspection Flow

EPTiF Inspection FLow


We provide 3 models to meet customers' various needs.

Single panel type
Industrial system type
Residential system type
Panel type Mono-/Poly-crystalline panels and strings, CIS panels and strings (filters are necessary), HIT panels and strings
Detection Inactive cell area, cracks, defective soldering, degradation by PID, broken fingers, etc.
Number of panels inspected at a time 1 panel
1 PV string
1 PV string
Camera InGaAs camera
Resolution: 320x256 pixels (non-waterproof)
InGaAs camera
Resolution: 320x256 pixles (waterproof)
Imaging time Approx. 10 to 30 sec/1 shooting
Signal input box (w/protection case), camera, PC
For EL excitation AC100V 50/60Hz 2500W Supplied by power-generating strings
(option: DC1000V/10A+10kW generator)
AC100V 50/60Hz 2500W
For control circuit AC100V 50/60Hz 500W
Warranty 1 year

Note) "HIT" is a trademark of Panasonic Group.


Environmental Products Sales Department
Matsuyama Factory, Japan Tel: +81 89 946 6605
Tokyo Headquarters, Japan Tel: +81 3 5817 8830