String Inverter vs Microinverters: Which to Pick

The short version: a string inverter on a 6.6kW system will usually cost you $500 to $1,500 less than the same system on microinverters. The harder question is whether that saving is worth it for your particular roof, and that comes down to shading, roof angles and how much you care about panel-level monitoring.

How the two actually differ

A string inverter is a single box, usually mounted on a wall near your switchboard. All your panels are wired in series into one or two "strings" that feed that one inverter, which converts the DC from the panels into the AC your home uses.

Microinverters flip that around. Each panel gets its own small inverter clipped under it on the roof, so conversion happens up top and AC runs down to the switchboard. There's no big box on the wall.

The practical consequence is how each handles a problem panel. On a string, the whole string tends to drop toward the output of its weakest panel. With micros, each panel runs independently, so one shaded or dirty panel doesn't drag the rest down.

The straight answer for most homes

If your roof is one clean plane facing north, east or west with no shading, a good string inverter is the sensible choice. You'll get the same yield as micros for less money, and quality string inverters from Fronius, Sungrow or SMA are reliable workhorses we've been installing for years.

If your panels have to go on multiple roof faces, or you've got a chimney, a whirlybird, a neighbour's tree or a two-storey wall throwing afternoon shade, microinverters (or a string inverter with DC optimisers) will earn back the extra cost in recovered generation. We see this constantly on the older homes around Dee Why and Mona Vale where roofs are cut up and gums are close.

Microinverters also give you true panel-by-panel monitoring. When a homeowner in Frenchs Forest rings us saying their output looks low, we can log in and see exactly which panel is misbehaving instead of guessing across a whole string.

Cost, rebates and feed-in reality

A typical 6.6kW system with a string inverter lands around $4,500 to $6,500 fitted after the federal STC rebate, which is applied as an upfront discount at point of sale. The same system on microinverters usually sits around $6,500 to $8,500 depending on panel count and roof access.

The STC rebate applies to the system either way, so it doesn't tip the scales between the two technologies. What matters more now is that feed-in tariffs have fallen to roughly 4 to 7c/kWh across Ausgrid and Endeavour areas. Exporting is worth little, so the value is in self-consumption. If shading is costing you generation during the day when you're actually using power, micros paying that back becomes an easier sum.

If a battery is on your radar, note the NSW battery incentive can reduce install costs. Both inverter types can pair with a battery, though the setup differs, so it's worth telling your installer your battery plans before the system is designed rather than after.

What we check on a quote visit

The single most common mistake we fix on other companies' quotes is a system designed on a satellite image without anyone looking at the shading. Software drops a string across two roof faces at different angles and pitches, which quietly clips your output for the life of the system. A five-minute look at the roof at the right time of day changes the whole recommendation.

We also open the switchboard. Older boards around Charlestown and the inner suburbs often have no spare space, no main switch of adequate rating, or ageing ceramic fuses that need to be dealt with before any inverter goes in. Micros can also mean more AC circuits landing at the board, so there needs to be room. Then there's metering: many homes still need the meter reconfigured or replaced for solar export, and if that's missed on the quote it becomes a surprise cost and a delay while the network processes it.

One more tradesperson note. Microinverters mean more connections sitting on your roof in the sun and weather, so we're fussy about using the correct connectors and torque. Done properly they're rock solid; done cheaply, a bad connection up there is a far bigger job to chase than a fault at a wall-mounted string inverter.

Which one is right for your roof

There's no universal winner. A simple, unshaded roof usually suits a string inverter and the money you save is real. A complex or shaded roof usually suits microinverters, and the extra spend buys back generation and clearer monitoring.

If you'd like an honest recommendation for your place, book a free on-site assessment with us across Sydney, the Northern Beaches and Newcastle. We'll check your roof, your switchboard and your usage, then quote both options where it makes sense so you can decide with the full picture.