Lots of home solar panel arrays have the potential to harvest more energy than their inverter can convert… but why? Photo: Mondiaux Solar.
Canberra residents are pretty “solar savvy” these days. One element of the renewable energy boom still has them stumped though, and it’s to do with how their inverters are sized.
In the past, virtually all solar systems featured panels and an inverter of equal capacity.
Now many installers recommend having an array of panels with a holding power larger than that of your inverter. This is called inverter oversizing.
In essence, it means the power produced by your system is determined by the inverter, not the panels themselves.
But don’t worry, you’re not spending extra on more panels for nothing. There’s a good reason for the gap.
One of Mondiaux Solar’s most experienced renewable energy consultants, Brian Zhang, says even though oversizing is commonplace in 2025, many homeowners have been left wondering how it works.
“Basically, we oversize to compensate for energy loss caused by external factors,” Brian says.
“Your panels aren’t always harvesting at full capacity. There are lots of factors out of our control that can reduce output, like sun position, weather, temperature, shade, even air pollution.
“Having more panels to draw from helps your inverter operate at a consistent level, even when individual output is low.”
There’s also a cost component. Current solar panel prices are fairly low thanks to subsidies, but increasing inverter capacity will set you back by at least $200 per kilowatt.
Buying extra panels is often more cost-effective than upgrading your inverter. Photo: Mondiaux Solar.
Oversizing allows your system to convert more energy when conditions are just right, delivering peak power for longer once the sun has left its prime position.
“This increases your overall daily production,” Brian says.
“We compared the daily inverter production of a regular system with one oversized by 133 per cent, both under optimal conditions. The oversized system showed an increase in production of around 10 to 15 per cent.”
There is an increased risk of energy clipping to consider, but most installers will tell you the benefits of inverter oversizing far outweigh this potential drawback.
Energy clipping occurs when more solar energy is harvested by panels than what their inverter can handle, essentially “wasting” potential power.
The ACT allows for a maximum of 133 per cent oversizing in systems without a battery. For example, a 6.6kW array could be paired with a 5kW inverter, or a 13.3kW array with a 10kW inverter.
Battery-connected systems can increase the oversizing ratio up to 200 per cent, though exact figures vary brand to brand.
The higher the ratio, the more potential a system has to save or earn money.
But Brian says the true value of inverter oversizing is how it increases efficiency.
“People do worry about their panels not performing in overcast or low-light weather,” he says.
“It’s one of the biggest factors, other than cost, holding people back from investing in solar. Oversizing helps mitigate this, without locking you out of Sustainable Household Scheme incentives.”
Customers who finance their system through Mondiaux Solar before 31 March could be eligible for $1000 cash back – T&Cs apply. For more information, visit Mondiaux Solar.
