Holding on to power

batteryIn past issues we have looked at various battery storage technologies. Recently we have received some questions about the broader topic of battery storage as it affects householders. In this article, we explore the concept of battery storage and the key considerations householders and businesses need to make when deciding on its suitability and type.

Currently, many Australian households pay 20-30 cents per kWh (note: kWh is a unit of energy) of electricity, and receive 5-7 cents per kWh, both depending on their retailer. Some early adopters of solar systems may still be receiving the ‘premium’ 60 cents per kWh Feed in Tariff rate for excess renewable energy exported to the grid.

Given the unfavourable Feed in Tariff (FiT) rates, it is in the household’s best interest to consume the electricity before it gets exported. Not all households will be running enough appliances while their solar PV system is generating electricity, resulting in a net export of electricity at the applicable FiT rate. Battery storage systems allow that excess energy to be captured during the day and stored for later use at night.

The solar PV system will need to be large enough to generate surplus electricity to charge the batteries during the day. The length of time the batteries can power your house depends on the capacity (size) of the battery. Battery storage systems come in a number of sizes and chemistries. The most common battery chemistry in use is the Lithium Ion (LiOn) which is available in sizes ranging from approximately 2-15 kWh.

Some key considerations need to be made when deciding whether to adopt battery storage and which type of storage.

  • Economic reasons: Currently, battery storage systems experience a payback period of greater than 15 years for many households. This is out of reach for many households. However, the good news is that the cost of battery storage is continuing to decline. For example, a 14 kilowatt=hour battery from Tesla currently costs about $10,000 installed which is approximately the same price as the original Powerwall despite having double the capacity.
  • Battery backup: The battery storage system can power your house in the event of a power failure. The length of time it can power your house during a power outage depends on the capacity of the battery, its current state of charge (how full it is) and its power rating (how quickly can you draw power from the battery, stated in watts).
  • Going off-grid: Depending on your circumstances, battery storage may be justified for off-grid solutions, particularly if there is a significant cost to connect your property to the main power grid.

For more information on battery storage, please call Positive Charge on 1300 236 855.

2 thoughts on “Holding on to power

  1. One thing I have learned since starting negotiations to buy a battery pvc system is that if you stay connected to the grid, to maintain access to your electricity when mains fails, you need a system with TWO inverters.

    • MEFL’s battery expert Steve Turnock has done some research and replies:
      This is correct, but is dependent on the type of battery system installed. An inverter is essential for any grid-connected solar PV system to convert DC power coming from the solar panels to AC for connection with the switchboard. If an AC-coupled battery system is added, an additional hybrid inverter is required to convert into DC for storage and back to AC for use in the house. With correct battery management software, this can also then maintain household operations if the grid fails. Some of the latest battery offerings have this additional ‘smart’ hybrid inverter built in. If a DC-coupled system is added, it is possible to run the system with a single inverter but will only conform to Australian standards if grid isolation can be assured in the event of an outage. A good article about AC and DC battery configurations can be found here.

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