# Solar Cells From Polycrystalline Cast Si

| Here is a typical poly-Si slice and a solar cell made from a similar slice. The dimensions are 10 cm x 10 cm.
|  | While the poly-Si slice is relatively fine grained (probably form about 1993), the solar cell (from about 1998) shows coarser grain structures - demonstrating the progress made in casting technology
|  | How good are polycrystalline solar cells? Not too bad, actually, but not as good as solar cells from very good single crystals.
| Below are four color coded maps showing essential parameters lod solar cells locally . These maps are not easy to obtains; they result from a new technique, developed by a university of Kiel research group, called "CELLO" (short for "Cell Local"). More details via the link. The parameters measured are:
|  | "Current", meaning the maximum (short-circuit current) that can be drawn from a pixel.
|  | "Voltage", meaning the voltage a pixel would produce if it would be an isolated cell by itself.
|  | "Series resistance ", essentially meaning the ohmic resistance that would be found in an equivalent circuit for one pixel
|  | "Process defects", a lumped parameter that displays serious local problems like, e.g., locally leaking pn-junctions.

| The progress made with multi-crystalline Si solar cells in comparison to competition is shown in the picture below

With frame

3.1.3 Mechanical, Thermal and Other Properties

3.2.2 Polycrystalline Silicon

© H. Föll (Semiconductors - Script)