{"id":93436,"date":"2025-07-28T06:09:13","date_gmt":"2025-07-27T20:39:13","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=93436"},"modified":"2025-07-30T05:14:49","modified_gmt":"2025-07-29T19:44:49","slug":"battery-storage-capacity-mb3234","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/battery-storage-capacity-mb3234\/","title":{"rendered":"Battery Capacity Confusion: Here\u2019s What The Jargon Really Means"},"content":{"rendered":"

\"Home<\/p>\n

Failing to understand jargon like the difference between ‘nominal’ and ‘useable’ capacity can leave homeowners with less battery storage than expected and even disqualify their batteries from the federal rebate. Here’s what it all means and why it matters.<\/p>\n

Scattered among SolarQuotes’ home battery customer reviews<\/a> of various brands are a few comments from disappointed Australians who didn’t get quite the amount of storage they expected. When determining the size (capacity) of battery you’ll need<\/a>, it’s important to understand several related terms.<\/p>\n

Nominal (Or Total) And Useable Capacity<\/h2>\n

Nominal or total capacity, described in kilowatt-hours (kWh), is simply the total amount of energy1<\/a><\/sup> a battery can store. Useable capacity is the amount of energy that can actually be accessed for your use.<\/p>\n

Using the example of a Sigenergy Sigenstor<\/a> 5S-13, its datasheet indicates a total capacity of 13.44 kWh, and a useable capacity of 13 kWh. But the difference between nominal and useable capacities in home battery systems varies.<\/p>\n

The difference is particularly important to understand if trying to claim the federal battery rebate<\/a>, for which the nominal<\/em> (total) capacity of 5 kWh to 100 kWh will be eligible, but only the first 50 kWh of usable<\/em> capacity is discounted.<\/p>\n

Why the difference?<\/h3>\n

Leaving a small amount of capacity untouched helps to avoid damage to the battery and increase its service life. The good news is you won’t have to do mental gymnastics figuring out how much you can use after it is installed. Whatever the solar battery’s useable capacity is, that’s all you’ll be able to access.<\/p>\n

Depth-Of-Discharge (DoD)<\/h2>\n

But sometimes the useable capacity isn’t specified on a datasheet \u2014 just a total or nominal figure, or even just ‘capacity’. If that’s the case, then this is a flag to look for another term: Depth-of-discharge (DoD).<\/p>\n

Depth-of-discharge means how much of the total capacity of a battery, expressed as a percentage, is useable. For example, if a 10 kWh battery has a DoD figure of 90%, that means it has 9 kWh of useable capacity. Usually a DoD figure (if present) for a lithium-ion based system will be 90% – 95%. It’s also important to go beyond the datasheet and marketing materials, and closely examine the warranty document as well \u2014 more on this in a bit.<\/p>\n

Don’t Forget To Factor In Backup Reserve<\/h2>\n

Many Australians are buying home battery systems for their backup capabilities. Backup reserve allows you to specify how much stored energy is set aside for use during a blackout. This limits the amount of useable capacity you’ll have for day-to-day use.<\/p>\n

Using the Sigenstor 5S-13 example again:<\/p>\n