{"id":93170,"date":"2025-07-22T08:26:14","date_gmt":"2025-07-21T22:56:14","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=93170"},"modified":"2025-07-22T11:01:55","modified_gmt":"2025-07-22T01:31:55","slug":"dont-blow-rebate-on-big-battery","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/dont-blow-rebate-on-big-battery\/","title":{"rendered":"Don’t Blow Your Rebate On A Battery That’s Too Big To Fill"},"content":{"rendered":"

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On the back of the federal rebate, huge batteries are on sale for bargain prices. There’s a catch to many of these deals however: you can’t possibly hope to actually charge these monster batteries to capacity as they are paired with completely inadequate inverters. Here’s what to watch out for.<\/p>\n

In a bid to make the rebate useful for businesses, the Cheaper Home Batteries Program<\/a> discounts as much as 50 kWh of the usable capacity of a battery system – much more than most residential households could need.<\/p>\n

This in turn has sparked an arms race of advertisements promoting ever-bigger batteries at ever-smaller prices for homes that simply don’t need them. The cheapness however isn’t just down to the rebate discount – there’s something crucial these batteries are missing.<\/p>\n

All Capacity, No Power<\/h2>\n

My old mate Sam had a Landcruiser “shorty” called Daisy. The previous owner had installed an additional fuel tank, more than doubling the total capacity to 183 litres. With a modest 85kW 4 cylinder using 7.8litres\/100km (30mpg) Daisy had a ludicrous range of 2300km. That’s almost Adelaide to Perth, 25\u00bd hours straight.<\/p>\n

So if you get a 5kW inverter and a 50kWh battery as we’ve seen advertised in one instance, you’ve got the same combination: modest power output and a novelty oversized tank. The trouble is this doesn’t offer the same advantage that it is does for a car’s range. An average full day of sunshine on 6.6kW of solar will only half fill the battery. Or charging from the grid, sweating its arse off, the inverter will take 10 hours straight.<\/p>\n

Once filled, you wouldn’t be able to extract the energy particularly fast either: 6kW to run the toaster, kettle and dishwasher would mean you’re still importing energy from the grid despite a charged battery. And the backup capacity from a 5kW inverter isn’t going to run your whole house in a blackout.<\/p>\n

A general rule of thumb, subject to your particular needs, is a 2 or 3-to-1 ratio for battery and inverter size: so a 5kW inverter being appropriate for a 10kWh or 15kWh battery.<\/p>\n

Be Aware Of Power and<\/em> Kilowatt Hours<\/h2>\n

The key is to understand the difference between kilowatts (peak rating) and kilowatt hours (storage units).<\/a><\/p>\n

For another car analogy:<\/p>\n