Every June, the same conversation happens across homes in Australia. The power bill arrives, and solar production is down. Someone says, “I thought we had solar?” and someone else says, “It doesn’t work as well in winter.” Everyone nods. The bill gets paid.
There’s nothing wrong with that explanation. But this year, it’s dangerously incomplete.
The real problem isn’t because it’s winter (or any season for that matter). It’s that the economics of rooftop solar have changed dramatically in the past 12 months. And the truth is, many haven’t adjusted their habits, their systems, or their expectations to match. Sure, the sun is lower in the sky, but the far bigger issue is that the rules governing what your solar is worth have changed underneath you while you were busy with other things.
Here’s what’s actually happening, and what to do about it before July.
3 cents vs. 35 cents
Let’s start with the uncomfortable truth that most seasonal solar content glosses over.
Feed-in tariffs (FiTs) have been falling steadily for years. In 2026, they typically range from 3-10 cents per kilowatt-hour, depending on your state and retailer. Energy Australia has already notified customers that its rate will drop to 3 cents per kilowatt-hour from 1 July 2026. Other retailers are moving in the same direction.
Meanwhile, the average household is paying between 30 and 35 cents per kilowatt-hour to import electricity from the grid. In Victoria (VIC), where mandatory time-of-use tariffs now apply to most customers, the peak rate between 4pm and 9pm has risen to around 37 cents per kilowatt-hour.
Do the maths: every kilowatt-hour of solar energy you use yourself is worth 6-10 times more than you export. That ratio has completely inverted the logic of how you should be running your home.
This matters more in winter than any other season. Because in June, your solar generation window shrinks to roughly four hours of useful peak output, typically between 10am and 2pm. Every kilowatt-hour generated in that window is precious. Wasting any of it to the grid at 3 cents, then buying it back at 35 cents that evening, isn’t a small inefficiency. It’s a structural hole in your household budget that repeats every single day.
Before we get to behaviour, though, you need to know whether your system is even performing as well as it should be.
Check 1: The shadow your tree didn’t cast in January
In December, the sun reaches roughly 76 degrees above the horizon at solar noon in Sydney. In June, that drops to around 32 degrees. The practical result: the shadows cast by trees, chimneys, aerials, neighbouring rooflines, and pergolas are dramatically longer and fall across areas of your roof that were completely unaffected 6 months ago.
Even partial shade on a single panel can reduce your entire system’s output by up to 10%. In a standard string inverter system (which is what most homes installed before 2020), that shading bottleneck cascades across the entire string of panels connected in series, not just the shaded one. One shadow, multiple panels compromised.
What to do:
Go outside twice on the next clear day. Check the roof between 9am and 10am, then again between 11am and 1pm. You’re looking for anything casting a shadow that wasn’t there last summer: a tree that’s grown, a neighbour’s new pergola, a satellite dish that moved. You’re also looking for it at the angle the June sun actually takes, which is far lower than where you’ve been mentally picturing it.
Then open your monitoring app. If your system has panel-level or string-level data, look for any string producing less than 70% of the others on a clear day. That discrepancy is diagnostic. It tells you the problem is a specific physical cause, not just seasonal variation.
If the culprit is a tree you can trim, do it. If it’s structural, the practical answer is a micro-inverter or power-optimiser retrofit, which now makes financial sense given current self-consumption economics and the cost of ongoing losses.
Check 2: The film on your panels is costing more than it used to
By June, most panels in southern and eastern Australia are carrying weeks of accumulated grime from autumn leaf fall, neighbourhood fireplace soot, and general dust buildup.
Research from the National Renewable Energy Laboratory estimates a 5-10% efficiency loss due to soiling. On a 6.6-kilowatt system generating at 60% capacity during a winter day, that’s a real dollar loss every clear day. At the 2022 FiTs, you could almost justify ignoring it. You were exporting most of your midday generation anyway, and the loss was absorbed. At today’s self-consumption value of 30-35 cents per kilowatt-hour, a clean panel is meaningfully more valuable than a dirty one.
What to do:
You don’t need to go on the roof. A wet winter roof is a fall risk, and panels can be safely cleaned from the ground using a telescopic hose attachment or a long squeegee with an extension pole. Use plain water. Avoid detergents, which can leave residue that attracts more grime. Don’t use cold water on panels that have been sitting in direct sun, though this is less of a concern on a cool winter morning.
While you’re assessing, check for bird activity around the edges of your array. Pigeon droppings are acidic and corrode panel surfaces over time. Nesting under the array is a common winter issue and can damage wiring. If you’re seeing it, it warrants a professional inspection and mesh installation before it becomes a warranty issue.
Check 3: Your appliances are running on the wrong schedule
This is the highest-leverage check for most households, and almost nobody has updated their habits since installation.
When solar was installed on your roof, you may have been told to “run appliances during the day.” Good general advice. But this month, specifically, “during the day” means a very narrow target: 10am to 2pm, 4 hours, on clear days only. Outside the window (and especially after 4pm), you are buying expensive grid electricity.
Here’s the practical reframe. A 2.5-kilowatt split system running for 2 hours between 12:30pm and 2:30pm draws roughly 5 kilowatt-hours of energy from your solar panels. It heats your living space using electricity that costs you nothing. A well-insulated Australian brick veneer home holds that warm for 2-3 hours. You arrive home at 6pm into a pre-warmed house and don’t touch your heating until 7pm or later, by which point peak pricing has eased.
Contrast that with switching the heating on at 5:30pm on grid power at 37 centres per kilowatt-hour. Same physical outcome. Very different bill.
What to do:
- Pre-heat, don’t re-heat: Set your split system to come on at 12:30pm on a timer or schedule. In most systems, this takes 3 minutes to configure and has no ongoing cost.
- Stack your heavy appliances consecutively: Running the dishwasher and washing machine at the same time often causes your system to dip into grid import because the combined draw exceeds what your panels can supply. Run them back-to-back instead, both inside the solar window.
- Use the delay-start function on your appliances: Almost every washing machine and dishwasher sold in the last 8 years has one. Set it tonight to start at 10:30am. You’ll recover that 30 cents per kilowatt-hour difference every time you run a load.
Check 4: Your inverter is probably older than you think
Solar panels are rated to last 25 years or more. Inverters typically last 10-15 years. If your system was installed between 2010 and 2016, your inverter is now between 10 and 16 years old. It is approaching or has reached the end of its design lifespan.
This matters in June specifically because heavy winter rain is the most common trigger for isolation faults in ageing inverters. Water ingress or even just elevated humidity causes the inverter’s internal monitoring to detect a ground fault and shut the system down or throttle output to protect itself. The system appears to be “working” in the sense that the inverter shows a green light. But it’s generating a fraction of what it should.
If your system is generating less than 50% of its expected output on a series of clear days in a row, that’s not a winter dip. That’s a system problem.
What to do:
Cross-reference your monitoring app with the physical inverter display. They should agree. If they don’t, there’s a communication fault worth investigating.
Note any amber lights, blinking patterns, or error codes. Photograph them. Most inverter error codes can be diagnosed remotely by a qualified installer, but they can’t diagnose what they don’t know about. If your system is more than 10 years old and hasn’t had a professional inspection in the last 2 years, June is a sensible time to book one.
A quick diagnostic question to ask yourself: do you know which generation your inverter is? If your honest answer is “I have no idea.” That’s worth finding out.
Check 5: The battery question that has a July 1 deadline
This isn’t a soft recommendation buried at the end. It’s a genuinely time-sensitive financial decision, and if you’ve been vaguely considering a battery for years without acting, the numbers have now moved decisively.
Australia has crossed 400,000 home battery installations since the federal Cheaper Home Batteries Program launched in July 2025. Daily installations have gone from around 200 per day before the scheme to over 1,500 per day. This is now a standard infrastructure for the Australian home.
The federal rebate currently offers approximately 30% off the upfront cost pf an eligible battery system, adjusted from 1 May 2026 to taper support for larger systems, while maintaining full support for standard household sized. That rebate will continue to decrease as the program phases down toward its 2030 end date.
Here’s why winter makes the case more clearly than summer does. In June, your solar generates a surplus in the middle of the day. That stored energy then covers your household consumption from 4pm to 9pm, during peak pricing. In VIC, that’s the difference between 3 cents and 37 cents per kilowatt-hour. In New South Wales (NSW) and South Australia (SA), similar dynamics apply.
Summer gets all the attention in battery conversations because the solar generation numbers are bigger. But winter is actually when the arbitrage between export rates and peak import rates is sharpest, because the gap between what you’d earn exporting and what you’d pay buying back that same energy in the evening is proportionally enormous relative to your reduced generation.
If the FiT cut landing on 1 July has made this feel more urgent, that instinct is correct.
What this actually adds up to
None of these checks individually solves a large problem. They represent the difference between a solar system that is working and a solar system that is working for you.
Australia has more rooftop solar per capita than any country on Earth. More than 40% of Australian homes now have panels installed. The tech works. The problem, the one that’s easy to miss against the backdrop of a lower winter sun and a predictable seasonal dip, is that the economic environment those systems operate in has changed significantly, and the habits, configurations, and maintenance routines of most households have not.
Your system was probably set up, optimised, and mentally filed under “sorted” at the time of installation. That made sense then. It doesn’t reflect where you are now.
Open your monitoring app. Look at yesterday’s generation curve. Find the peak hour. If it wasn’t between 10am and 1pm on a clear day, or if the shape looks flatter than it should, you have a starting point for investigation. If you haven’t looked at the app in 6 months, that’s your first answer right there.
If your system is more than eight years old, a professional winter health check is worth booking now, before the next billing cycle. Solar Service Guys can assess and service your system, covering inverter diagnostics, string testing, and panel inspection. If your system is newer and you’ve been weighing up a battery, the window to act at the current rebate level is open, but it won’t be indefinitely.
