A New Inverter Costs Over 12 Panel Cleans, and Its Warranty Ends Well Before the Panels'

Is solar panel cleaning worth it at today's feed-in tariffs?

The answer depends on what each lost kilowatt-hour would have earned. IPART's all-day solar feed-in benchmark for NSW in 2026-27 is 3.4 to 6.5c a kWh, down from 4.8 to 7.3c in 2025-26, and retailers are not required to offer within it. On our assumption that every kilowatt-hour lost to dirt would otherwise have been exported at 6.5c, the top of that range, a professional panel clean ($200) costs about 3,080 kWh of exported power at Going Rate's prices. At the 3.4c bottom of the range it costs about 5,880 kWh.

To turn that into a share of a year's output, our worked example assumes a 10.5 kW system in Sydney, built from two sourced figures. The Clean Energy Regulator says the average small-scale solar system installed in the June quarter of 2026 was 10.5 kW, an average that covers every system under 100 kW, homes and businesses alike. YourHome puts typical generation in Sydney at 4.0 kWh per kW per day. On those assumptions, a 10.5 kW system in Sydney makes about 15,330 kWh a year.

On our assumption that all lost output is exported at 6.5c, a clean pays for itself only if dirt would have cost about a fifth of that year's output. At 3.4c the break-even is nearly two-fifths. Regional Queensland gives a similar answer to the top NSW rate. On the same all-exported assumption, the QCA's 2026-27 regulated tariff of 6.006c and YourHome's Brisbane yield of 4.2 kWh per kW per day put break-even at about a fifth for a 10.5 kW system. A clean also wins power back only until the dust settles again, so the true bar sits higher than these figures.

How much power does dirt really cost Australian panels?

Measured Australian data is thin. A 2018 Murdoch University PhD thesis by Julius Tanesab found dust cost modules 4 to 6% of their power over one year in Perth, against 16 to 18% in tropical Nusa Tenggara Timur, Indonesia. It is one study in one Australian city.

The other common figure is a design allowance. The Clean Energy Council's December 2012 design guidelines for accredited installers, since replaced by later issues, said that if in doubt an acceptable de-rating for dirt would be 5%. On our worked example at 6.5c, the break-even of about a fifth is roughly four times that 5% allowance, and three to five times the Perth measurement.

Overseas estimates are global. The IEA's solar program says soiling causes 4 to 7% of energy losses worldwide, and its 2022 soiling report deals with power plants. For Australian homes, SolarQuotes' Ronald Brakels estimates that cleaning twice a year would lift average output by around 2% for most households, and cites a Tucson study in the US that found about 1%.

Export or self-use flips the answer

Power you would otherwise buy from the grid is worth far more than power you export. The Essential Services Commission's 2026-27 Victorian Default Offer sets flat usage rates of 25.96c a kWh in the CitiPower area to 31.98c in AusNet's, including GST. Victoria has had no regulated minimum feed-in tariff since 1 July 2025, so retailers set their own, as long as it is not below zero. IPART says most customers get the best value from their solar panels by using the electricity they generate rather than exporting it.

On our assumption that every lost kilowatt-hour would have replaced power bought at the Victorian Default Offer, the sums change. YourHome puts Melbourne's yield at 3.6 kWh per kW per day, so on our assumed 10.5 kW system it makes about 13,797 kWh a year there. A professional panel clean ($200) then breaks even if dirt costs about 4.5 to 5.6% of a year's output, right on the 5% design allowance. Real homes sit between the two cases, and the split between exported and self-used power varies from house to house.

Perth is harder. Western Australia's buyback scheme pays Synergy customers 2c a kWh for power exported from 9pm to 3pm and 10c from 3pm to 9pm, and only systems with a generating capacity of 500 W to 5 kW qualify. On our assumption of a 5 kW Perth system exporting all lost power at the 2c rate, a clean costs about 10,000 kWh of exports, more than the 8,030 kWh a year that system makes at YourHome's 4.4 kWh per kW per day.

When a panel clean earns its keep

Tilt does most of the cleaning. YourHome says that on panels mounted at a slope of more than about 10 degrees, most dirt and grime should wash off when it rains, and that cleaning is only needed in some circumstances, such as a very dusty location. The Murdoch thesis found dust deposition fell as tilt increased, and attributed Indonesia's greater losses partly to lower tilt angles. One modelling approach in the IEA's soiling report resets soiling to zero on any day with more than 1 mm of rain.

CHOICE said in 2021 that rain does the job for most people with angled panels, and named very dry climates, animal droppings and overhanging vegetation as the cases for a professional clean. Flat panels are the clearest exception. SolarQuotes reports that Google found cleaning its flat panels after they got particularly dirty could double their output.

The Murdoch thesis recommended one clean a year for the Perth test system and two for the system in Indonesia. A home with flat panels, heavy dust or a roost of birds is the best case for booking a professional panel clean ($200). A steep, rain-washed Sydney roof is the weakest.

The inverter bill arrives before the panels age out

At Going Rate's prices, replacing an inverter ($2,500) costs twelve and a half times a professional panel clean ($200), and more than a quarter of a household solar system ($9,000). One clean costs about a forty-fifth of the system. On our worked Sydney example of a 10.5 kW system exporting at 6.5c, the inverter equals about two and a half years of output.

Warranties show why the inverter comes first. YourHome says string inverters have warranties of around 10 years, that a 5 to 10-year warranty is common for string, battery and hybrid inverters, and that the best policies may run to 12 years. It puts microinverter warranties at 10 to 25 years. Most panels are guaranteed to make 80 to 90% of their original output after 25 years. Sungrow's Australian warranty covers its inverters for 10 years from installation, capped at 11 years from manufacture. Enphase extended a 25-year limited warranty to all IQ8-series microinverters activated from 1 October 2024, pv magazine Australia reported at the range's Australian launch.

A common 5 to 10-year string inverter warranty covers 20 to 40% of a 25-year panel guarantee. On our assumption of spreading the cost over a 10-year warranty, the top of that common range, a replacement inverter ($2,500) costs about one and a quarter cleans a year at Going Rate's prices, and two and a half cleans a year over a 5-year warranty. Anyone pricing a household solar system ($9,000) with a 25-year horizon should budget for another inverter.

How long solar inverters and panels last

Hard failure data for inverters comes from Europe. A Bern University of Applied Sciences study of 1,195 systems and 2,121 inverters found more than 65% of the inverters had no yield-relevant fault by their 15th year of operation, pv magazine Australia reported. SolarQuotes says the systems were in Switzerland and most were commissioned from 2008 to 2013. Outdoor installations failed sooner. On those numbers up to about a third would develop a fault inside 15 years, and some of those owners would face replacing an inverter ($2,500).

Panels age slowly by comparison. Jinko's Australian warranty for its listed N-type panels, one maker's terms, allows 1% degradation in the first year and 0.4% a year after that, with at least 87.4% of nominal power at year 30. NREL measured a median loss of 0.75% a year across almost 2,500 US commercial and utility-scale sites, with 0.88% a year in hotter climates.

The Murdoch thesis found Perth modules left uncleaned for almost 18 years had lost 8 to 12% of their maximum power, a total that includes ageing as well as dust. Over the life of a household solar system ($9,000), the inverter is the part most likely to need money.

Servicing every two years is a different job from cleaning

Energy Safe Victoria recommends having a home solar system serviced at least once every two years, and says servicing is not simply cleaning the panels. Solar Victoria gives the same two-year advice and says some distributors want an anti-islanding check of the inverter once a year. CHOICE took a different view in 2021, quoting its expert as saying a service once every five years or so should be sufficient in most cases.

Energy Safe Victoria also warns owners to check their warranty, because servicing by a company other than the installer can void it. Solar Victoria says to never use a pressure hose on panels and that water is usually enough. A service that checks the inverter, wiring and isolators can catch faults before an inverter replacement ($2,500), while a professional panel clean ($200) only restores what dust has taken.

Common questions