Pvi20 Front Cover indd

Fill factor losses
There are three main mechanisms for the 
fill factor 
FF
losses of a solar cell: (1) loss due 
to series resistance (
R
s
); (2) loss due to shunt 
resistance (
R
sh
); and (3) loss due to non-ideal 
recombination. The two resistances 
R
s
and 
R
sh
(under maximum power conditions) are 
measured, and an advanced 
FF
loss analysis 
[8] then allows the corresponding 
FF
losses 
to be extracted. 
Series resistance losses 
The (measured) 
R
s
of the solar cell under 
maximum power conditions can be broken 
down into more detail if the layout of the 
metal contact grid is known (see Fig. 8(a)). 
For simple contact-grid layouts (such as the 
H-patterned grid shown in Fig. 8(b)), there 
are several analytical programs available 
in order to calculate this breakdown [9]. 
p-type c-Si 
p
++ 
Front-surface recombination (J
0fp
, J
0fc
) 
Bulk recombination (J
0b
) 
Rear-surface recombination (J
0rc
) 
Figure 6. Sketch of a standard industrial Al-BSF solar cell, indicating the different solar 
cell regions which contribute to recombination losses.
Front, non-metallized
13%
Metal
87%
Figure 7. Voltage losses of a typical industrial p-type Al-BSF solar cell.
Figure 8. (a) Breakdown of measured series resistance of a standard industrial p-type Al-BSF solar cell processed at SERIS; 
(b) the simple H-patterned metal grid used. The total series resistance due to the front grid and the bulk were calculated to be 
0.44Ωcm
2
, and the remainder of the series resistance (0.16Ωcm