The business case for a home to install solar / What size solar do I need?

The business case for a home to install solar / What size solar do I need?

We advise people to install a system that’ll generate at least ½ your Winter daily usage. If you can install a larger system, that will probably be beneficial (depending on your energy use), and you will be more likely to still receive a feed-in tariff during the Winter. If you think you might like to have a battery in future, then ideally your system will be 5kW or larger. 



  • Most homes have an average daily usage of 14-15 kWh

  • 1kW of solar panels will generate approximately 4kWh of electricity p/day

  • So, a 5kW solar system will generate about 20kWh on a clear, sunny day


A typical 2021 system will pay for itself within 3-5 years (in the form of lower bills). 


Typical costs for a 5kW system are currently: 


$5500-8000 (with a single inverter for the entire system - works less efficiently, but this may not be an issue on a north-facing roof with no shading)

$8000-9500 (with individual inverters on every panel - more efficient but more expensive)



Feed in tariffs: 

Feed in tariffs have dropped, however, solar is still worth it, due to a 60% drop in solar costs since 2012. While the expense of early 2010’s solar panels made high feed-in tariffs financially necessary at the time, the last 8 years have seen decreased
manufacturing costs. This means that high feed-in tariffs are no longer needed to make solar a wise investment. Even with low tariffs, the typical 2020 solar system will pay for itself within 3-5 years (in the form of lower bills). 
The lower feed in tariffs mean that it currently makes financial sense to use as much of the power that you generate as you can, rather than sell it back to the grid.