Micro Inverters: Sometimes Brilliant… Sometimes not.
Alright, let’s call this one what it is.
Micro inverters are not some magical “premium” solar upgrade. They’re a specific tool for a specific problem. And if that problem doesn’t exist on your roof… you’re probably paying for a solution you don’t need.
Here’s the straight story.
The 10-second version
Got shade? You might need them.
Don’t got shade? You don’t need them.
That’s it. Blog over.
(…fine, let’s unpack it properly.)
First things first: the only brand that matters
If you’re even thinking about micro inverters, you’re looking at Enphase Energy.
Not “one of the options.” Not “a good option.”
The option.
Why?
They dominate the global micro inverter market
25-year warranty (which is massive in inverter land)
They actually back it — including paying installers to replace failed units
They’ve even got an R&D presence here in New Zealand
Everyone else is playing catch-up while Enphase laps the track.
What is a micro inverter (and why do people like them)?
Instead of one inverter on the wall, micro inverters put a tiny inverter under each panel.
So instead of:
Panels → one inverter → house
You get:
Panel → inverter → house (repeated 20+ times)
The massive upsides - mostly in shaded scenarios
1. Panel-level monitoring
You can see exactly what each panel is doing. Great for diagnostics. Also great if you enjoy obsessing over graphs.
2. Fault finding is easier
If a panel stops producing, you’ll know which one.
Reality check: panel failures are rare anyway.
3. Shade mitigation
This is the real reason micros exist.
If one panel is shaded, it doesn’t drag the rest down.
4. No high-voltage DC on the roof
Everything converts to AC at the panel. Some people like this from a safety perspective.
5. Panels operate independently
Each panel does its own thing, at its own best output.
6. Warranty comfort (on paper)
25 years is impressive. And Enphase does honour replacements.
7. Slight winter gains
You might see ~3–5% better performance in low-light or uneven conditions.
String inverter reality (as compared to Micro Inverters)
With a standard string inverter (Fronius, Sungrow, SigEnergy, etc) - panels are wired together in “strings” (series circuit). A string of panels is a group of panels. A typical string can contain anywhere from 3 to 15 panels, and maybe a little more on three phase systems.
Most string inverters have two to four string inputs.
That means:
The current through the string is limited by the worst-performing panel
If one panel is shaded, it can drag down the output of the whole string
Sounds bad, right?
Well… not as bad as it used to be.
Modern panels havebypass diodes, which allow electricity to “skip” shaded sections of a panel. So instead of one shaded panel killing your whole system, you usually get:
A partial drop in that panel
A smaller knock-on effect to the rest of the string
Bypass diodes have a tolerance of about 30%. So - if a panel section is shaded by more than 30%, it will bypass. If one section of a panel is bypassed, and the other 2 sections are in direct sun - there is practically zero impact to the rest of the panels in the string.
Most panels have 3 vertical sections, each guarded by a bypass diode. So in heavy shaded scenarios - like a neighbouring 2 story property that casts as slow moving shadow - a panel can be flipped around into landscape, so that the shade moves across the panel sections one by one, as the sun moves.
Where it gets dicey is if a panel is only a little shaded. If the bypass diode doesn’t activate, a 10% loss from a small branch or bird poop will pull down the performance of the other panels in the string. Not good.
Bypass diodes are not ideal — but they’re not catastrophic either. But ultimately, if your panels aren’t installed under shade, you’ll have zero concerns.
Panel mismatch is also part of the conversation. Not all panels perform the same. Micro inverters allow the star panels to shine, which is almost insignificant in the first couple of years, but becomes more important as time goes on. For example - our director Rowan has Solar Edge Optimisers, which act almost the same as micro inverters, and his 6 year old panels have a mismatch of around 5%. That means if he had a string inverter, his system would perform around 5% worse, even on a sunny day.
Micro inverter reality
Micro inverters flip the script.
Each panel operates completely independently, so:
One shaded panel only affects itself
The rest of the system carries on unaffected
This is where micros genuinely shine.
Shade: Where Micro Inverters Actually Win
With a micro inverter system, each panel operates on its own little island.
If one panel cops some shade from a chimney, vent pipe, palm tree, or that one neighbour who thinks macrocarpas are a personality trait… only that panel takes the hit.
So if one panel is producing 20% less power, the rest of the system keeps humming along normally.
String inverters work differently.
Instead of every panel operating independently, panels are connected together in groups called strings. Think of it like a team tied together with a rope. If one runner slows down, everyone gets dragged back a bit.
So if a shaded panel in a string loses 20% of its output, the entire string tends to get pulled down with it.
Now — this is where things get sneaky.
Some modern solar panels are genuinely much better at handling shade than others. Better cell layouts, bypass diode designs, half-cut cells, and current pathways can massively reduce how badly the shaded panel itself suffers.
That matters.
A good panel might only lose 10% output from a bit of shade, while a cheaper or older design could lose 30%.
But here’s the important bit most brochures conveniently skip:
Even if the panel handles shade brilliantly… the rest of the string still follows whatever loss that panel experiences.
So if the shaded panel loses 10%, the whole string roughly follows that 10% reduction.
If the shaded panel loses 30%, the whole string gets dragged down far harder.
That’s why premium panels with excellent shade tolerance can absolutely improve string inverter performance — but that doesn’t mean they beat micro inverters.
Here’s where it gets… less shiny
1. Summer losses (the bit no one leads with)
New Zealand typically gets the 385W-rated Enphase micro.
Most modern panels?
460W+
So what happens?
Clipping.
Your panel can produce more than the micro can handle — so it gets capped.
Clipping isn’t a disaster, infact - we’ve got a blog that talks about intentionally oversizing your solar inverter, and claim that a little clipping isn’t a worry. However, our comments around clipping are weighed against the cost benefits of saving your pennies and considering a smaller inverter than your array size.
Unfortunately, Micro Inverters give you the clipping, but not the cost savings you get from intentionally under sizing a string-based solar inverter.
2. The battery penalty (this one stings)
With micro inverters, you’re limited to AC Coupled batteries.
It’s tough to explain what AC Coupling means in 5 seconds, so instead - lets imagine the Micro Inverters are like a generator in your shed. If you want to store energy from the generator in a large battery, you need an ‘inverter charger’
… An inverter charger is basically a solar inverter, but is designed to work both ways - AC to DC and DC to AC.
Well… Its no different with Micro Inverters. If you want to put AC energy from your Micro Inverters into a battery, you need an inverter charger between the Micros and the battery. This adds a lot of cost, and really limits your options.
That means your energy does this:
DC (from the panels) → AC → DC (battery) → AC (house)
Each conversion yields a ~2% loss, or more.
So:
3 conversions yields a >6% loss.
A standard DC-coupled system only yields a ~2% loss, because the DC energy is only converted once into AC current!
Sometimes the loss per conversion can be greater than 6%, and depends on how much energy is being ‘inverted’. Google ‘Solar Inverter Efficiency Curves’.
IE - A Fronius Gen 24 8kW model is 94.1% efficient at 5% load. … 5% load is basically your lights and wi-fi.
And guess what - An Enphase IQ8 Micro inverter is 94.5% efficient at a 5% load. Not much difference.
So, for those with DC Coupled systems, where the DC to AC conversion only happens once, the ‘round trip efficiency’typically sits between 95 and 98%. But with an AC Coupled battery, its not uncommon for the round trip efficiency to hover around the 90% mark.
Conservatively though, and keeping the ~2% loss per conversion:
Micro Inverters yield THREE TIMES the energy loss when paired with an AC Coupled battery, as compared to a DC coupled system like most other things in the market.
This is not marketing spin. Just physics and the hard reality.
Top top: You can pair Micro Inverters AND the most favoured batteries, but you can’t have just the batteries. Lets say you had 20 Micros installed and wanted a SigEnergy battery - you’d need to buy the SigEnergy Inverter as your ‘inverter charger’ ($5000 ish for the 10kW unit), PLUS the Gateway ($1500 ish), AND the batteries at about $7000 per 10kWh unit. But you’ve already spent $5000 on your precious micro inverters. OUCH. And even with all that cost, you’d still be AC Coupling the system and experiencing 3X the losses from inversion/conversion.
… If you just got a DC Coupled system in the first place, it would cost a lot less (no micro inverters needed). And yup, you wouldn’t have individual monitoring and performance, but you also wouldn’t suffer the extra ~4% loss from the extra conversions.
3. Cost (where things get… creative)
Here’s the trick some in the solar the industry like to pull, they compare:
20 panels + micro inverters
vs20 panels + string inverter
They talk about how much better 20 panels with Micro Inverters perform in winter, and in shaded scenarios. But - that’s not a fair fight! 😂
A real-world comparison is closer to:
20 panels + micros - costs about $21k
vs24 panels + basic grid tied inverter - also costs about $21k
Same outlay but…
👉One system has Four extra panels.
We’ll come back to that.
4. Failure rates (the rooftop elephant in the room)
Here’s the uncomfortable truth:
Solar panels have extremely low failure rates. IE - Most solar companies might replace 1 in 500 over a 10 year period.
Micro inverters have meaningfully higher failure rates. Industry estimates often sit around 1–2% per year depending on conditions and batch)
Here’s a cheeky reddit thread covering real client experiences. Don’t be afraid to ask AI on this!
Now multiply that:
20 panels = 20 micro inverters
20 potential failure points
Installers love to say:
“Easy to replace!”
Sure. But let’s be honest. What’s easier?
Swapping an inverter on the wall next to your switchboard
orSending someone onto your roof to pull apart your array?
5. The share price question (read between the lines)
Not financial advice — but it’s worth knowing:
Enphase Energy stock has dropped roughly ~90% from its 2022 peak (~$311 USD).
Now — that doesn’t mean they’re going anywhere.
But it does reflect investor confidence.
And when you’re buying a 25-year warranty, that’s not irrelevant.
So… should you get micro inverters?
Let’s bring it back to reality.
You probably should consider them if:
Your roof has partial shading (trees, chimneys, weird rooflines)
You’ve got multiple orientations that are hard to optimise
You value panel-level visibility
You probably shouldn’t if:
Your roof is clean, simple, and unshaded
You want maximum ROI per dollar
You’re planning to add a battery
You’d prefer 2 - 4 more panels for the same price.
Final thought
Micro Inverters are magnificent when used for their genuine purpose, which is - shade mitigation.
But some companies over prescribe them. If you’re lucky enough to meet a micro inverter salesman, you’ll understand why we had to write this blog.
😅They’re more determined than anyone to sell their product.
Simple framework:
If you’ve got shade and you can’t put the panels anywhere else:
They’re brilliant and totally worth the investment. Get the Micro’s.
Don’t got shade?
No need. Save your pennies and put them towards a battery, or a few more panels.
