Assuming you want net metering, you’d need controls in place for grid safety and such and all the permits and inspections which take time and cost money.
I imagine all that is pretty standard here also - South Australia isn't exactly without regulation or seemingly high labour costs. I used the same company at the office building and then at home, and each was painless. Approve an easy quote and then everything is later installed on a particular day. Both were in the 5-10kW range.
At the office building, the estimated payback was all of two years.
