These rebates are means tested for combined ($100k), so it if you are under that then read the fine print that some of these companies are asking in relation to signing over your future carbon credits. Also I was under the impression that the PV cells are only 25% efficient ATM. That is only 250w from a 1kw system will make it back into the grid or your home. That would mean that with the average house uses about 1,5kw per day making the up only about 1/6 of your power requirements. At that rate at a saving of about $60 per qtr all things being equal or $240 per year.  Not pretty