This domestic installation in rural South Australia was designed to run as a grid minimisation installation. Although the grid remains connected it is rarely used to power the house, although excess power is exported to take advantage of the feed in tariff available.
Before the battery installation this household had a 5 kW solar PV system installed with a Fronius solar inverter.
The battery installation was done in stages as requirements changed.
The original battery installation had one 9.6 kWh SoNick battery with 2 Victron 3 KVa Multigrid inverters and a Victron colour controller for communication.
A second 1.5 kW solar array was also installed that was connected to the SoNick battery via an MPPT to make sure the battery would always have a power source if for some reason the battery was to go flat. Unlike lead acid or lithium there is no damage to the SoNick battery if it goes flat, however in order to start charging again the Victron inverter needs to see a voltage across the battery terminals. This is achieved as soon as the sun starts to charge the solar panels.
The area had very poor internet connection and remote monitoring proved to be difficult due to the intermittent connectivity.
Sodium Nickel Chloride (SoNick) batteries were selected due to their inherent environmental characteristics and lack of fire risk, meaning there are no safety issues with installing the batteries. Another consideration was the lack of degradation with the SoNick batteries, meaning they would expect to have the same capacity in 10 years time where most lithium batteries would have degraded substantially in 5 to 10 years.
Lithium-ion batteries weren’t considered due to the difficulty in recycling lithium batteries at end of life and to their inherent fire risk.
After a couple of years, it was decided to add another 9.6 kWh SoNick battery into the system and to upgrade the Victron inverter to a 5kVA Victron Multiplus-II inverter.
The second SoNick battery connected seamlessly to the first one that was several years old with no need to balance cells of different ages. As there is no degradation with SoNick batteries there are no issues installing extra batteries at a later date. The batteries do not always charge at the same rate due to one battery having a newer BMS, however they both charge to 100 % capacity which confirms the lack of degradation.
Application – independent domestic power supply
System Objective – to provide grid minimisation installation capable of supplying off-grid backup supply during blackouts,
Commissioned – 2018, upgraded 2021
Installed PV – 6.5 kW
Inverter – Victron 5 kVA Multiplus-II
Battery storage – 19.2 kWh
Communications – Victron Colour Controller
If you would like to know more about getting safe, reliable, recyclable, SoNick (molten salt) battery storage for your own home, business or micro-grid application visit us at https://gridedge.com.au/