17th June 2008 - 08:53 AM
I was wondering what happens to an entire solar pv panel if a single pv cell gets damaged?
If the cells are connected in series does it mean that the whole panel will fail?
Is there anyway to know if a single cell is damaged in commercial solar panels?
20th June 2008 - 12:20 AM
Solar cells are usually connected in series strings which are then connected in parallel.
The most common defect is an open circuit, in which case one complete string doesn't provide any more current.
However, where reliability is important (in space), people put Schottky diodes antiparallel to each solar cell, so that other cells in a string can force their current through this diode if the cell is open.
Each string can also have a series diode which prevents a faulty string, which would in this case have a short circuit, from lowering the voltage supplied by the sound strings.
This all assumes that diodes are more reliable than solar cells. Realistic, but diodes sometimes fail as well.
To know if a cell is damaged, measure the voltages. Each silicon cell should deliver about +0.45V in full sunlight, an open cell will show a negative voltage imposed by the neighbours in the string.
The voltage at mid-string is measured more quickly than individual cells.
8th July 2008 - 02:20 PM
thx a lot for your help!