A 3kW solar system is the next most common system size in Australia after the 1.5kW system. 3kW systems are well suited to medium to larger households of 4+ people which is why they have become the more popular of the larger end systems.
Some important figures to keep in mind for 3kW solar systems:
|Average Price ($)||How many panels?||Average Energy Generated Daily (kWh)|
|$4,200 – $7,000||12 – 16 (depending on panel size e.g. 190W)||12 units|
* Note that the energy generated daily is an average for the year; in summer this will be higher but conversely in winter it will be lower. Also this is an average across all of Australia and so there will be a variation depending on exact location.
Using these figures, you can calculate a payback period for an average 3kW system of 4.2 – 7 years. If you also take the average pricing, energy use into account along with the rising cost of electricity, your system will have paid for itself within 5 years.
These figures not only take into account power sold back to the grid, but also consider energy usage offset by not having to buy power from the grid. For every unit you don’t pay for from the grid you save yourself about $0.22. This may not sound like much but over a year that adds up to about $990 on a 3kW system. These savings only increase if (when) the price of electricity increases.
For placing the panels of a 3kW system you have look at what your own energy use is like. The 3kW systems can be placed facing in either 1 or 2 directions based on what kind of inverter you have.
The typical household has low load in the middle of the day when people are at work/school and a peak in the late afternoon early evening when everyone gets home. These types of households may benefit more from facing their panels in a more westerly direction to get the peak generation closer to the evening when the most power is being used. However, if people are home during the day then it would be better to have your panels face as north as possible and peak during midday.
Alternatively you can have half panels facing west and half north and have them act like two individual 1.5kW systems. This will give a smoother power output during the day, but obviously won’t reach the same peaks as all panels facing the same direction.
In the end you want to maximise the use of the solar you generate in order to minimise how much you have to buy from the grid.