If you are an electrician you can learn about getting accreditation to install solar power systems here. Once you are a clean Energy Council Accredited Installer you can install solar and claim STCs on the installation.
If you are not an electrician you can still get accredited to design solar systems by becoming a Clean Energy Council Designer.
This pdf shows what courses you have to do for the type of accreditation you need. Each state has TAFEs that run these courses.
A really good commercial training outfit is GSES.