SolarQuip home solar power installations
Standalone power system training system, Swinburne University of Technology

Solar battery storage is a more complex setup but is still low maintenance.

Solar battery backup systems have become a popular way to save on electricity bills and gain more energy independence.

A battery backup system allows you to store energy while the sun is shining and use that energy at night or on cloudy days.


What Makes a Battery Storage System Attractive?

Is it common for the power produced by a solar power system to exceed the power being used during sunny periods. It may be a home where you are out during the day or there is simply less demand for power.

In a grid connect system, that excess power can  be exported to the electricity grid, earning you a credit on your power bill.

However, in most cases the amount paid for electricity exported to the grid is well below the price you pay when you buy electricity. So you may create power and sell it to the electricity retailer, only to buy back in the evening at a higher rate.

With an on-grid battery storage system, that excess power can be used to charge your batteries. When you use power in the evening you are drawing on the energy stored during the day and may not need to pay for electricity.

A second advantage of having a battery backup power system is that it provides you with a greater degree of energy independence. It becomes an ‘uninterruptible power system’ (UPS), so that if an outage occurs in the electricity supply your system automatically switches to the battery supply for continuous power.

The higher cost of a solar battery backup system must be compared with the savings made through avoiding buying electricity from the grid.


What’s Involved in Installing a Grid Connected Battery Backup?

Solar battery storage installation and trainingA grid connect solar battery storage system is certainly a more complex and costly setup.

The house can receive power now from three sources – the solar PV array when it is producing enough power, the battery bank, and the electricity grid.

The inverter is designed specifically for this application and for the given voltage of the battery bank. The inverter must maintain the health of the batteries and supply the 240V AC electricity supply to the house.

A regulator is usually installed to maximise the output of the PV array (by a process known as ‘Maximum Power Point Tracking or MPPT) and to charge the batteries at a controlled rate.

Solar batteries are a specific type of battery designed for regular deep cycling so that you can draw the most out of the batteries on a regular basis while still maintaining a good battery life.

Batteries are commonly bought as 2 volt or 12 volt units linked together to form a 12, 24 or 48V bank. Battery storage for solar PV systems is generally from gel type lead acid batteries although lithium phosphate batteries are approaching a price point where, with their longer life cycle, they may soon become cost competitive.

A battery backup system requires some maintenance that a regular grid connect system does not. The health of the batteries is a high priority due to the frequent use and the high cost of replacement. Regular monitoring is recommended to confirm that the system is operating as expected.