What is back surface field?
What is back surface field?
A “back surface field” (BSF) consists of a higher doped region at the rear surface of the solar cell. The interface between the high and low doped region behaves like a p-n junction. An electric field forms at the interface, which introduces a barrier to minority carrier flow to the rear surface.
What is the function of the back surface field?
Back Surface Field (BSF) has been used as one of means to enhance solar cell performance by reducing surface recombination velocity (SRV). One of methods to produce BSF is by introducing highly doped layer on rear surface of the wafer.
What is surface recombination?
The reduction of the number of dangling bonds, and hence surface recombination, is achieved by growing a layer on top of the semiconductor surface which ties up some of these dangling bonds. This reduction of dangling bonds is known as surface passivation.
Which technique is used to overcome surface recombination?
To achieve optimal operation, surface recombination is reduced by a passivating or window layer that prevents minority carriers from reaching the surface. Passivation of silicon surface by an oxide layer or the deposition of a thin “window” layer of GaAlAs on GaAs solar cells are just two examples of such practice.
What is PERC solar cell?
PERC solar cells are modified conventional cells that enable the cells to produce 6 to 12 percent more energy than conventional solar panels. PERC solar cells have an extra layer within the back side of the cell. This makes it easy for manufacturers to change and produce the higher efficient cells.
What is PERL solar cell?
PERL Solar Cells The passivated emitter with rear locally diffused (PERL) cell uses micro-electronic techniques to produce cells with efficiencies approaching 25% under the standard AM1. IV curve for a solar car cell.
What causes surface recombination?
Surface recombination This occurs when traps at or near the surface or interface of the semiconductor form due to dangling bonds caused by the sudden discontinuation of the semiconductor crystal. Surface recombination is characterized by surface recombination velocity which depends on the density of surface defects.
Which factors affect the surface recombination?
Factors affecting Recombination
- Number of minority carriers at the edge of the junction.
- The speed with which the carriers move away from the junction.
- The speed of recombination.
Which solar panel is most efficient?
Top 10 most efficient solar panels *
What are the features of high efficiency solar cells?
High Efficiency Solar Cells
- lightly phosphorus diffused emitters, to minimise recombination losses and avoid the existence of a “dead layer” at the cell surface;
- closely spaced metal lines, to minimise emitter lateral resistive power losses;
What is the highest efficiency of a solar cell?
The maximum theoretical efficiency calculated is 86.8% for a stack of an infinite number of cells, using the incoming concentrated sunlight radiation. When the incoming radiation comes only from an area of the sky the size of the sun, the efficiency limit drops to 68.7%.