Have had a 4.2kw system for 5 years now. Producing between 5 and 5.5 MWH per year. I installed a 5KW SolarEdge Inverter so that I could expand to 6kw of panels as the price of power increased. I also installed a SolarImmersion device which isolates the hotwater tank from the grid for all but 2 hours per day and any surplus power is sent to the hotwater tank instead of going to the grid. Works great in the summer and provides close on 100% self consumption in the winter. June and July I use the boost button to connect to the grid for an extra hour each night. The system has worked flawlessly for 5 years. Am looking to move to Christchurch in a year or so and will get solar installed on the new house. With 5 years experience I will go for a Fronius string inverter instead of the more expensive SolarEdge with optimisers so that most of the money is spent on panels on the roof where it counts, On the whole very pleased.