Most 6.6kW solar systems are quoted with a 5kW solar inverter…
In Australia we have a federal based incentive to go solar known as STC’s or Small Scale Technology Certificates. STC’s are calculated on the size of the solar system, the installation State or Territory and the deeming period for these STCs.
The STC scheme allows the capacity of the inverter installed at the premises to be oversized with panels by 33%.
This same 33% rule carries across to the Clean Energy Council and your electricity distributor, who are the people who put up your poles and wires.
What this means is, the most panels you can legally put on a 5kW inverter to save money and help drive those headline prices is 6.6kWs. If you go over 6.6kW’s you would need a bigger inverter or second inverter which then drives the price up which makes it hard for the high turnover, low margin retailers out there.
However, oversizing a 5kW inverter with 6.6kW’s of solar panels is a good design move.
It would need to be the perfect day for your solar system to produce its total capacity not to mention site specific influences such as panel orientation. What is more important is the total daily generation of the solar system. A 5kW Solar System on a 5kW inverter will generate less then a 6.6kW Solar System on a 5kW inverter and the cost difference won’t be much when you consider STC’s.
Installing a 6.6kW Solar System will allow you access the maximum amount of STC’s on a 5kW inverter, it will also ensure your distributor is happy regardless if you have single or three phase power.