Generally speaking, the solar panels on your roof act as the primary source of electricity for your home, with the grid acting as storage and, at times, back up. If the solar panels on your roof are creating more power than is needed by your home, then the excess goes into the grid. Later, if your panels can’t produce enough electricity, electricity is drawn from the grid to make up the difference.

More and more, people are asking about the battery capacity it would take to replace (or assist) the grid in the above scenario. But there’s no one-size- fits-all answer to this question. It depends on several factors, which we have listed for you below. Consider each point in the context of your own needs and wants and this will help you (or help us to help you!) decide on the correct battery capacity for your solar storage needs.

Energy independence

You may want to be 100% independent and go completely off-grid (which is a big job, and not always possible), or you may just be after an energy storage system for emergency back up. These are the two extremes, but there are levels of energy independence that fall in between. For example, you can equip your home with enough solar and battery storage to be self-sufficient during winter, relying on the grid only during days of very poor weather. Or you might only want/need a system that allows you to be self-sufficient during summer, thereby falling back on the grid throughout the darker months.

You can also install a storage system large enough to completely cover OR reduce your grid electricity usage during peak times (peak-time independence) – this avoids use of the grid when electricity is most expensive. The level of energy independence you wish to achieve will influence the capacity of your storage battery.

Amount of electricity you use

For a home that uses low levels of energy, the battery storage system will only require a small capacity, and therefore be relatively cheap and easy to install. Low energy consumption is classified as anything under 20kWh per day. The higher your household energy usage is, the more storage capacity you will require, and the higher your upfront costs.

Size of your solar PV system

If you would like to add energy storage to your preexisting solar system, then this will impact the amount of storage capacity you can/should get. As an example, if you are exporting a lot of solar energy to the grid, you may want a larger battery and storage capacity to capture it all.

However, if you are looking to install an entirely new solar system from scratch, then it may be financially more feasible to make it produce only enough electricity to meet your household demand and then have a small energy storage system to capture any excess. If you want to move toward greater energy independence then oversizing your solar system and installing a large battery bank would be the way to go – and may be your best financial option depending on your circumstances and what you currently pay.

Orientation of your roof and solar panels

Panels that face north will generate more power than those that face east or west. However, panels that face west can do a better job of meeting your household’s electricity needs during peak times.

Want to continue this discussion? Our Total Solar Solutions team is on standby to help you with your next step – give us a call on 1300 486 825 to talk all things solar.