Understanding the PV Solar Cell and module

The Solar Cells are available in the form of a single crystal cylindrical ingot. This is known as monocrystalline silicon cell.

The manufacturing process of solar cell is highly energy intensive process wherein the ingot is sliced into thin wafers of about 100 – 200 µm through diamond-saw process. During the wafer slicing process half the material is wasted in sawing and forming square cells. The molten silicon is passed into ingots (square cross section). Though the conversion efficiency of polycrystalline silicon cells is lower due to random distribution of silicon crystals, but the polycrystalline cells are cost effective and cheaper as compared to monocrystalline silicon cells.

The different wafer sizes of solar cells are classified as per M0, M2, M3, M4, M6, M10 & M12 standards. For example, a typical M0 standard silicon cell size is about 156 mm × 156 mm (6 in × 6 in). In recent years there has been trends to increase the cell sizes and module sizes and the cells are available with 210 mm × 210 mm known as M12 standard.

The typical cell power of M12 cell is about 9.92 W and a 660 W_p module has about 132 cells of this standard. In recent years, in order to reduce the cell resistance, the concept of half cut mono perc cell has been introduced. The cells are from M12 standard and cut half to reduce the cell resistance. The word Perc stands for Passivated emitter rear cells (Perc). The introduction of perc technology not only improves the efficiency of solar cells but also improves module performance against light induced degradation (LID) and potential induced degradation (PID). The half-cut cells also reduce hotspot generation in the modules.

The mono perc cells also show good performance at higher temperature as the half-cut cells have lower temperature coefficient as compared to full size modules. The typical specification of a 540 W_p half-cut mono perc module are as follows: –