To achieve high efficiency solar cells, series resistance plays a major role, and front side grid resistance is one of the components. The front side grid resistance on its turn is dependent on the print definition and print quality. A practical assessment of the grid resistance & print quality is to measure the resistance in between two busbars (B2B resistance).
SunLab B2B is made for measuring the resistance of all fingers between two busbars on an H-pattern solar cell. The B2B resistance is a direct measure for the print quality. At the same time the B2B resistance is the information needed to quantify the resistance of a finger and to obtain a direct value for modeling, etc.
Busbar to busbar resistance
When optimizing the front side print definition, e.g. through varying on paste, or when testing new screens or improved line definition in the screens, it is important to have a good measure. The busbar to busbar measurement is a simple and straightforward method for this.
Day to day or run-to-run print quality in production can vary and is dependent for instance on screen wear, paste transfer though the screen, paste supply, local temperature, etc. It is therefore important to have a direct measure for the most critical part of the front side print: the fingers. Here too, the busbar to busbar resistance is a simple and straightforward measure.
In order to reduce power losses associated with front side metallization, efforts converge in producing fine conductors with high aspect ratio. Fine lines reduce shadow losses and allow finer pitch which reduces the resistive losses in the emitter. High aspect ratio, thus large cross section area, reduces resistive losses in the conductor. Practice involves balancing the resistive losses (finger and emitter resistance) and shadow losses by designing an optimum pattern. In case fingers can be optimized, the number of fingers on the front side may have to be increased. For this modelling the finger resistance is needed.
Measurment display of the B2B.
Fast and simple storage of measurement data.