Economics of adding Battery Storage to an existing Solar System


Daily Profile with ValuesValuing a Battery Storage System

This article considers using excess electricity generated by the solar system to charge the batteries. Energy stored in the batteries is then used when the solar system is no longer producing sufficient electricity to meet the household’s electricity needs.

When used in this way the value of the battery system is determined by the cost of electricity no longer purchased from the network less the credit that would have been earned for excess solar electricity sent to the network. On a single rate tariff available to Sydney households the difference is currently 17c/kWh


Return on Investment Battery StorageReturn on Investment

The installation of a battery storage system can reduce the annual electricity bill. While this may be sufficient for some households, most will want to ensure savings over the lifetime of the battery storage system recover the costs. This calculation is best performed using the Return on Investment.

Using actual measurements from 300 Sydney households and the published price of a 7kWh battery storage system the article presents the Return on Investment. For a Sydney household with an average sized solar system of 2.5kWp the analysis reveals:

The average household loses 7.7% p.a. by installing a battery storage system



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Copyright of this article remains with Dr Martin Gill. All references to this article should include the author’s name and website

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