Battery technology is an area that is currently undergoing rapid changes, and there are exciting new developments that we are keeping an eye on. In the meantime, for the average home there are two sound options at this point in time.
Option 1: Use and store your own solar
Remain connected to the grid but store excess solar generated electricity in a battery which can then be used during the evening when energy prices are at their peak. The grid is then used as a backup when there is insufficient power left in the batteries.
Under this option you minimise the amount of energy you need to import at prices of around 25c/kwh. However, you must remember that had you exported energy to the grid you would have received 10c/kwh from Enova, so the economics really need to be worked out on an overall saving of 15c/kwh. The economics of this option depend on the size of your solar system, how much energy you use in the house during the day when the solar panels are producing energy and how much energy is left to be then stored in the batteries.
Typically, midsize battery systems can cost anywhere between $7000 and $14000. Savings from avoided energy purchases are hard to estimate, but could be $400 to $500 p.a. This means your pay back is currently over 15 years. It is unknown if batteries will last that long.
Option 2. Go completely off grid.
Typical off grid systems cost anywhere from $25,000 to $50,000. It would be also be sensible to also have a back-up generator. The savings in energy costs may be around $2000.p.a. So again, this is an option that is unlikely to break even cost-wise in under 10 years.
As prices of batteries drop over the next few years, what may be uneconomical today could be economical in 3 or 4 year’s time. Our recommendation is perhaps, for the moment, adopt a wait and see approach.
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