This domestic installation was designed to run as a grid minimisation installation. Although the grid remains available it is actually switched off.
The house is a rural property and is completely electric so electricity usage is higher than it could be for a normal suburban house. Water pumps, electric fences and all electric cooking can use a lot of electricity. Although the electric hot water uses evacuated tubes to heat with solar, this is often not enough in cooler months so the solar / battery system also heats the electric hot water tank.
The system consists of 11.2 KW QCells solar PV panels on a 25-degree pitch
1 x Victron 450/250 MPPT
2 x 9.6 kWh SoNick batteries which equates to 15.5 kWh recommended useable storage
1 x Victron 10 kVA Qattro inverter
1 x Victron Cerbo as the brains of the system which allows the whole system to be monitored remotely and any changes to the system can also be done remotely.
There was also a 6.75 KW 2nd hand Canadian Solar PV panels system with a Victron 450/150 MPPT already installed that was connected into the new system. Unfortunately, these panels were only on a 10-degree pitch so weren’t extremely effective.
As with all off-grid installations care is taken to use as much electricity using available solar during the day. This means equipment like washing machines and dishwashers, ovens and other cooking appliances are always used during the day while the sun is available and if possible, in the afternoon once the batteries are full.
This is an area with frequent power outages, often for many days so the ability to have power in an off-grid installation when the grid wasn’t available was the original impetus for investigating the off-grid solution.
Sodium Nickel Chloride (SoNick) batteries were selected as they have the highest energy density of any batteries and are completely safe with no off-gassing or fire risk, meaning there are no safety issues with installing the batteries.
The batteries are located in a garage which can get very hot in summer but temperatures can also get below freezing in winter. As, the SoNick batteries operate with no temperature effects and no degradation from -20°C to +60°C there are no issues with either heat or freezing temperatures that are often experienced and the batteries don’t require air conditioning to keep them cool or heaters to heat them enough for them to work. Many lithium batteries claim to work between 0°C to +45°C, however, they often are charging and discharging at a much slower rate at anything outside 5°C to +40°C. Many lithium-ion battery warranties also have clauses limiting the number of hours or days that batteries can operate at temperatures above +35 – 40°C. They can also degrade much faster when operating at the temperature extremes.
Another reason, lithium-ion batteries weren’t considered was due to the difficulty in recycling lithium batteries at end of life and to their inherent fire risk if improperly disposed of.
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/