**Principal Investigator**
Gernot Heiser **Project** g32

School of Computer Science and Engineering, **Machine**
VP

University of New South Wales

**Co-Investigators** Alistair
Sproul, Christiana Honsberg and Sean Edmiston,

Centre for Photovoltaic Devices & Systems, University of New South Wales

**Simulation of Silicon Solar Cells**

This project uses two-dimensional numerical modelling to study the internal operations of the novel multilayer thin film solar cells which are presently being developed at the Centre for Photovoltaic Devices & Systems, UNSW. These cells are to produce energy at competitive prices, and are therefore manufactured from inexpensive, low quality material.

**What are the basic questions addressed?**

The main purpose of this project is to study the effects of material defects on solar cell performance, and to help derive design rules which will result in reasonably efficient cells. In 1995 the main focus of the work was on investigating the effect of inter-layer injection on the series resistance of multilayer cells.

**What are the results to date and future of the
work?**

The results showed that in the single-crystaline cases investigated differences between 1D and 2D simulations are relatively small. More significant differences were expected when investigating polycrystalline material. However, these simulations proved too time-consuming even for the VP machine and were therefore suspended, pending further work on simulation methodology.

**What computational techniques are used and why
is a supercomputer required?**

The simulations solve a coupled system of non-linear
partial differential equations by the Rfinite volumeS method.
The systems of linear equations resulting from discretisation
and linearisation are generally extremely ill-conditioned, which
makes them impossible to solve by iterative methods and lead to
convergence problems even with direct solvers. We typically use
about 20,000 to 40,000 grid points and require in excess of 200MB
RAM, more than what used to be available on workstation kind of
machines. However, recently Sun SPARC and DEC Alpha based workstations
with large memories have become available to us, resulting in
a discontinuation of work on the VP.

**Publications**

*Modelling of Thin-file Crystalline Silicon Parallel
Multi-junction Solar Cells,* S. Edmiston,
A. Sproul, M. Green and S. R. Wenham, Progress in Photovoltaics,**
3(5)**, 333-350 (1995)