I put a 2.75 KW system on our house under the .44c scheme. Unfortunately I only put in a 3KW inverter. So I can put another 250W panel on the roof to increase my output to 3KW but if I change the inverter to a larger unit to add more panels I revert to the new scheme.
The agreement is on the size of inverter not the number of panels. I so much wish I had of had the foresight or knowledge at the time and I would of put in a 5KW inverter so I could continue to put more panels on the roof as I could afford to do it.
I reckon in SA it is based on your actual installed system size, not inverter size. Looking at the paperwork lodged by the installers to the authority for my system, they asked specific details on the number of solar panels installed and the rated panel output, which then led to the obvious question about total maximum system sized installed. From what I understand most systems have a slightly bigger rated inverter, than the system is capable of producing - I guess that makes sense.
Also the wording in other documents I have about the government solar rebate scheme is that it
only applies to the original installed system. In other words, if you replace it with an equivalent (output wise) system down the track, then technically you can't receive the same level of rebate you did with the original system, if that makes sense.
How would they know you had made a change?
I'm guessing if all of a sudden you're producing considerably more power than your system is supposedly capable, this would trigger a physical inspection of your system to determine whether there has been some tampering or changes.
Reminds me of the story about the clever electrician who realised that he received more in rebates per watt generated, than he would if he paid for the electricity off the grid through his provider. So he fed mains power into his inverter and the sat back and waited for the big rebate cheque to arrive in the mail at the end of the month. Sounds like a great idea but he didn't take into account he was feeding power back into the grid 24 hours a day..... I guess he had to explain how his solar panels managed to make power all through the night