Recently, after the severe weather event that hit Victoria on 9th June the ABC wrote an article comparing how a few different battery installations performed.
https://www.abc.net.au/news/2021-07-03/battery-power-dandenong-ranges-tesla-agm-grid/100264988
This article pointed out the importance of when purchasing an energy storage battery that it is fit for the purpose that you want it to provide.
Just like many people don’t initially realise that solar arrays don’t operate if the power is disconnected, battery storage systems don’t always work either.
This is fine if you just want a battery energy storage system to provide some load sharing but if you want power when the grid is disconnected the battery has to be capable of being used in an off-grid situation and it has to be wired to allow for this. This usually means the battery inverter is wired in before your solar inverter so that the complete battery and solar PV energy system can operate independently from the grid.
The type and size of your battery system is also important and how much of a battery systems capacity is actually useable. With lead acid and AGM batteries, generally only 30 – 50% of the batteries capacity is useable which means you will need a larger system capacity overall. Also as lead acid and AGM batteries tend to degrade over time and with use this needs to be taken into account when sizing your energy storage system.