“”

Solar Energy

The solar energy market is one of the newest markets to benefit from
vision. Solar power is a clean and attractive alternative source of
electricity, so there has been an increasing demand for photovoltaic
modules to be cheaper and become more efficient at solar energy
conversion. Solar cells are crystalline silicon devices and a variety
of imaging techniques can be used during manufacture. Cell breakages resulting from microcracks, degradation and shunted areas on cells are
proven to cause major problems and affect module performance. Many
such defects cannot be observed with conventional imaging systems. However a measurement method known as the Electroluminescence (EL) imaging is providing a solution.

Electroluminescence imaging

EL imaging consists of applying a direct current to the solar module
and measuring the photoemission using an NIR camera. The system is
able to accurately detect numerous failures and ageing effects in very
short times. Based on the severity of the defects, the cell will either be
accepted or rejected. In addition, the amount of light a cell generates for
a given applied current can also serve as a measure of the solar cell’s
conversion efficiency.

Edge isolation

Edge isolation is used to provide electrical separation between the
active front side of a solar cell and the rear side. In the edge isolation
process, a laser cuts a small groove along the cell edges, the depth of the
groove depending on the cell doping. The groove needs to be positioned
as close as possible to the outer contour of the cell in order to maximise
the active surface and thus the efficiency. By using a line scan camera
and customised LED illumination to measure the outer contours of the
cell and feed them back to the control system of the laser, the edge
cutting can be carried out automatically to within preset tolerances.

Contact:  Chris Valdes  T: +44 (0) 20 8773 5517     sales@machinevisionconference.co.uk

Organised by UKIVA Logo part of