Let’s clear something up right out of the gate: oversizing your solar inverter is not a sin. In fact, it’s smart—especially in New Zealand where our sun is abundant but not always perfectly aligned with your power needs.

Now, we get it. You’re wondering: “If my inverter is only 5kW, why am I slapping 6kW of panels on the roof?”

Welcome to the wonderful world of intentional oversizing, and no—it won’t blow anything up. Let’s unpack it.

What Is Oversizing?

Oversizing simply means installing more solar panel capacity (kW) than your inverter’s rated output. So if you’ve got a 5kW inverter and you install 6kW worth of panels, that’s a 20% oversize.

Some folks get nervous about this. “Won’t I lose energy to clipping?” Sure—maybe a few percent of total generation might get “clipped” on the sunniest days at peak noon. But we’re not living in a lab—we’re in the real world where solar panels are never at their full rating all day. Clouds, low-winter sun, all make a dent.

Here’s Why 20% Oversizing Makes Sense

1. You’ll generate more power earlier and later in the day.
   Those “shoulder hours” matter. More kWh across the day = better ROI.
2. You have a DC coupled battery
   You won't clip if that extra energy above your inverter rating bypasses AC conversion and goes straight into the battery. DC to DC!
3. Panels are cheap, inverters aren’t.
   Adding a few extra panels is far more cost-effective than jumping to the next inverter size (especially under NZ’s 5kW export limit on single phase).
4. Your panels face different directions.
   Just because you have a 10kW system, doesn't mean you're guaranteed a full 10kW. If your panels are East and West, good luck getting 10kW in the hour outside of November - February.

So What About the Clipping?

Yes, the inverter will clip the top off any generation that exceeds its max output. But let’s look at the numbers:

• On a perfectly sunny summer day, maybe 1–5% of the day’s generation gets clipped.
• Over a year, that’s basically a rounding error.
• And if you:
• Use a battery and time it to charge midday, or
• Face some of your panels east/west instead of all north,
  you’ll flatten the production curve and avoid most clipping altogether.

So… why wouldn’t you oversize?

The Kiwi Context: 5kW Inverter, 6kW of Panels = Sweet Spot

New Zealand’s single-phase homes often cap out at 5kW export limits. So your inverter can’t send more than that back to the grid anyway. But by putting 6kW (or even 6.5kW) of panels on the roof, you:

• Maximise generation when you need it,
• Reduce your reliance on the grid,
• And avoid the headache (and cost) of jumping to a 3-phase system if you don’t need it yet.

The large grid tied system: 8kW inverter, 9kW of panels and a timer or two

Got an electric hot water cylinder, or a combination of Spa pool and Water pump?

Chances are you'll do fine with an 8kW inverter and 9 kW of panels, or even more if you have a DC coupled battery!

... Generate 8 per hour between 11 and 2. 3 goes into your hot water cylinder (Or Spa and pool pump). 5 goes to the grid.

... Too easy.

The Final Word



If your solar installer tells you 20% oversizing is bad—they’re probably stuck in 2015. The modern reality is this: panels are cheap, inverters are smart, and clipping is strategic, not catastrophic.

So go ahead. Be a little oversized.

Because when it comes to solar, bigger (within reason) is usually better—especially when you're clever about it.

Want help designing a solar system that pushes the limits but plays within the rules?

We’ll find you a deal that doesn’t just work—it works smart.