How long does a solar inverter last? Not as long as your panels — and that's the bill nobody mentions.

As a planning assumption, a string inverter lasts roughly 10 to 15 years, a hybrid or battery-capable inverter roughly 10 to 12 years because it works harder managing battery charge and discharge as well as solar conversion, and microinverters roughly 20 to 25 years, often warranted to match the panels. Manufacturer warranties typically run 5 to 12 years depending on brand and whether an extension was purchased. The key implication is that the inverter will almost certainly not last as long as the panels, which are warranted for around 25 years, so a mid-life inverter replacement should be budgeted into the lifetime cost of any solar system. Heat is the main determinant of where in that range a particular unit lands: an inverter mounted in full afternoon sun or in an unventilated space will age measurably faster than the same model installed in shade with good airflow.

Replacing a typical 5 kW string inverter has commonly been quoted in the region of $2,500 to $4,500 including installation, while smaller repairs such as replacing a cooling fan cost substantially less. Treat those figures as indicative rather than a quote: pricing varies with brand, inverter size, whether you move from a string to a hybrid inverter, site access, and whether any switchboard or network work is required. Always get two quotes. Two things can change the number significantly. First, if the inverter is still under warranty, or if the failure was early for a premium product, Australian Consumer Law guarantees may mean you should not be paying at all. Second, if a battery is anywhere in your plans, replacing with a hybrid inverter now is usually cheaper than replacing like for like and paying again later for battery capability, because the labour and network paperwork are done once instead of twice.

Six signals, roughly in order of urgency. A fault light or error code displayed on the unit. A sustained drop in generation, which you can identify by comparing a clear sunny day now against a clear sunny day in earlier years in your monitoring data. Repeated dropouts or restarts, particularly on hot afternoons, which often indicate failing cooling. New or rising noise, such as a whine or a rattling cooling fan. Error codes that have become routine rather than occasional, since one isolation fault after heavy rain is weather but the same code weekly is a pattern. And finally, parts or support becoming unavailable because the manufacturer has left the Australian market, which turns an otherwise repairable fault into a replacement. Before concluding the inverter is failing, rule out the cheaper explanations: shading from a grown tree, dirty panels, genuine weather variation, or a network export limit that looks like a generation fault but is not one.

Age is the deciding factor. If it is still under warranty, claim it — go to your installer first, then the manufacturer, and note that your rights survive even if the installer has gone out of business. If it is out of warranty but under roughly eight years old, price the repair before assuming replacement, because a fan or board-level repair on a relatively young unit can buy several more years cheaply. If it is over roughly eight years old, replacement is usually the better economics, because every other internal component is the same age as the one that failed, so a few hundred dollars of repair often buys months rather than years, and a new unit resets the warranty. If parts or manufacturer support are unavailable at any age, replace, since every future fault will otherwise present the same dead end. Also consider Australian Consumer Law before paying: for a major installed product, a reasonable lifespan is frequently argued to be around a decade regardless of the written warranty.

Heat is the dominant cause. An inverter contains power electronics including electrolytic capacitors that degrade faster the hotter they run, so an inverter mounted in direct afternoon sun, or installed in an unventilated garage corner or a hot roof space, will fail measurably earlier than the identical unit in shade with good airflow. Beyond heat, common causes include cooling fan failure which then accelerates heat damage, moisture and dust ingress especially in coastal or dusty environments, voltage disturbances and grid events, insulation or isolation faults developing in the DC wiring, and simple component wear after a decade of daily cycling. Poor installation contributes more than people expect: an inverter positioned for convenience rather than ventilation is a common and entirely avoidable cause of early failure. If your inverter is currently baking in western sun, adding shade or relocating it is one of the cheapest life-extending actions available.

Often, yes. Australian Consumer Law guarantees operate alongside a manufacturer's warranty and are not limited by it. Goods must be of acceptable quality, which includes lasting a reasonable time given their price, the way they were described and what they are for. For a major, expensive, permanently installed product like a solar inverter, a reasonable period is frequently argued to be around a decade, so a premium inverter that fails at year six may well have a valid claim even though its written warranty was five years. Raise it with the retailer who sold you the system, in writing, describing the product, its price, when it was installed and when it failed, and referring to the consumer guarantee of acceptable quality rather than the warranty. If the retailer refuses or has ceased trading, escalate to the manufacturer and then to your state or territory consumer affairs or fair trading body. It is a genuine legal right rather than a long shot.