Did Lord Kelvin really say "If you can not measure it, you can not change it"?
It seems maybe not but it does not matter because when it comes to power or any form of electricity, this is absolutely true.
When you first start out to save power, your first and best option is efficiency. It does not help to drive inefficiency with expensive battery and photovoltaic power.
This will help you scope your project and ensure you buy the correct system.  

The above graph shows a PV system before and after the insulation of a 5kW SunSynk with 7.4kWh of SolarMD battery and 3.8kW of peak PV
Average usage before 35-38kWh per day, after 5-8kWh per day