Buying solar

The solar inverter: what it does, and what it costs you twice.

Panels are the part you can see and the part that almost never fails. The inverter is the part doing conversion work every daylight hour, and it is the component most likely to need replacing before the system is done. Here is how to choose one, keep it, and budget for the second one.

By Kieron Taylor, Founder, Solar Select · Updated · 8 min read

The 30-second take

  • The inverter converts DC from your panels into the AC your house and the grid use. Nothing works without it.
  • Four types matter: string (one box, cheapest), hybrid (string plus a battery connection built in), micro (one per panel), and optimised string (per-panel electronics feeding one inverter).
  • Single phase vs three phase is set by your house, not your preference — and three-phase hardware costs more and adds at least $500 to the installation.
  • Maintenance is genuinely minimal: keep it ventilated and shaded, keep the vents clear, and actually look at the monitoring.
  • Component prices run "$500 to around $5,000" for string units and "$600 to around $4,000" for hybrids; the replacement job is that plus an electrician.

What the inverter is doing all day

Solar panels produce direct current. Your house, your appliances and the grid all run on alternating current. The inverter sits between them and converts one into the other, continuously, every hour the sun is up, for as long as the system lives.

That is why it fails first. The panels are glass and silicon with no moving parts, bolted to a roof, degrading a fraction of a percent a year. The inverter is power electronics running hot under load through every Australian summer. Treating them as equivalent line items on a quote is the most common mistake in solar buying.

“The panels are the part you look at. The inverter is the part that works.”

The four types, and which one your roof argues for

  • String inverter. One unit on the wall; panels wired in series into one or more strings. Cheapest, simplest, and entirely correct on an unshaded roof facing one direction. Its weakness is structural: panels in a string are electrically bound, so the weakest panel limits the others.
  • Hybrid inverter. A string inverter with the battery connection already built in. Costs more up front and saves you buying a second box if you add storage later. If a battery is even possible in your future, this is usually the right call.
  • Micro inverter. One small inverter behind every panel, converting at the panel. No string, so no weakest-link effect, and a failure takes out one panel rather than the array. Highest cost per panel.
  • Optimised string. A DC optimiser behind each panel doing per-panel tracking, feeding one central inverter. The middle path — panel-level behaviour, one serviceable box at ground level.

The rule: if nothing shades your roof and it all faces one way, a good string inverter is the rational buy and per-panel electronics solve a problem you do not have. If you have a chimney, a neighbour's tree, a gable or three orientations, per-panel electronics buy back real generation for the life of the system.

Single phase, three phase, and the sizing rules

Whether you are single or three phase is a property of your house's grid connection, not a choice on the quote. Most Australian homes are single phase. If yours is three phase, the inverter has to match, the hardware costs more, and the labour costs more — SolarQuotes' own worked comparison puts three phase at "$900 more for the inverter" plus "at least $500 more for the installation".

On sizing, two things trip people up. First, the inverter is usually smaller than the panel array — a 6.6 kW array on a 5 kW inverter is standard practice, not a mistake, because panels rarely hit their rated output and slight oversizing captures more of the shoulders of the day. Second, your network sets an export limit, and that limit constrains the inverter rather than the panels. Ask what yours is before you agree a system size.

  • Count the MPPTs. Each maximum power point tracker manages its own string. A roof facing two directions wants two trackers, or the two arrays fight each other.
  • Check the inverter is CEC-approved. Only listed units are eligible for the federal rebate, and your installer must use one.
  • Ask where it is going. Direct afternoon sun on a west wall shortens the life of the most failure-prone component in your system.

Maintenance: what actually helps

Inverter maintenance is one of the lowest-effort, highest-return jobs in home solar, mostly because so few owners do any of it.

  • Keep the vents clear. Heat is what kills power electronics. Spiders, dust, leaf litter and a shelf stacked against the unit all do real damage over years.
  • Keep it out of direct sun. A unit on a shaded wall or under an eave runs cooler and lasts longer than the same unit baking on a west-facing wall.
  • Look at the monitoring monthly. Not daily — monthly. You are watching for a trend, not a cloudy Tuesday. A string that has quietly stopped reporting is the classic silent fault, and people find it years late.
  • Photograph the error code before you call. It shortens the diagnosis enormously and tells the sparky whether it is a grid-fault trip or a hardware failure.
  • Do not open it. There is stored DC voltage inside and no user-serviceable part.

Almost everything else marketed as "solar maintenance" is panel cleaning, which matters far less in most of Australia than salespeople suggest. The inverter is where attention pays.

What replacing one costs

Expect to do this once in the life of a long-lived system. On components, SolarQuotes' pricing guide puts string inverters at "$500 to around $5,000" and hybrids at "$600 to around $4,000", with micro inverters starting "as low as $195 apiece" and three-phase units at the upper end — SolarEdge three-phase models are listed at "$2500 – $3100". Higher-priced units bought for longer warranties and better support "can add an extra $1,000 to $3,000".

Those are component prices. A replacement is also an electrician on site, often a new isolator arrangement, re-commissioning, and in many cases a fresh notification to your network. Note too that these prices are "unlikely to appear as separate line items on your quote, which would also include installation cost" — so a replacement quote is one number, and the same rules about exclusions apply as on a new install.

The decision that follows: when comparing a budget inverter against a good one, the real comparison is not two sticker prices. It is one inverter against another inverter plus a second installation, some years earlier.

When your inverter brand has left the market

A specific and common Australian situation. ABB stopped making residential solar inverters, Aurora was the brand before it, Zeversolar and a handful of others have come and gone. If one of those is on your wall and it has failed, the warranty is often the least of your problems — there may be no local entity to claim against and no parts pipeline.

What still works in that position:

  • Diagnose before you replace. Not every fault is the inverter. A tripped isolator, a failed DC breaker or a grid voltage problem all present as "the solar has stopped".
  • A dead inverter does not mean a dead system. Panels and racking commonly outlive two inverters. Replacing the inverter on a healthy 10-year-old array is usually far better value than a whole new system, whatever a salesperson says.
  • Match the replacement to the array, not the old unit. String voltages, MPPT count and export limits all need re-checking against what is actually on the roof now.
  • Expect a compliance uplift. Standards have moved since older systems went in, so the replacement may require isolator or labelling work the original never had.

A cheap install is only cheap until something goes wrong, and an orphaned inverter is what that looks like a decade later. If yours has stopped, get matched with 2-3 vetted solar installers — typically 2+ years in business, with a track record of decent reviews — and get the fault diagnosed before anyone quotes you a new system.

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Sources

Every quantitative claim on this page traces to one of the sources below — government, manufacturer, or independent AU industry reference. Last verified 2026-08-24.

We use AI to help research and draft. Claims are traced to the sources below and dated. Where we haven’t got a source, we say so on the page — treat that as a starting point and do your own research.

General information only. It doesn’t take your circumstances into account and isn’t legal, financial, insurance or electrical advice. Rebates, tariffs, network rules and product terms change — confirm anything you plan to rely on with your installer, insurer, retailer or distributor, and see our terms.

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