Before going solar, households often ask: what happens when the sun is not shining? The reassuring answer is simple. Solar panels keep working on cloudy and rainy days. They produce less than on a clear day. However, they do continue to operate because they run on daylight rather than on direct sunshine alone. This guide explains how much a system still makes in poor weather. It shows why rain provides benefits rather than problems. It also covers what it all means for a Perth home.
The short version: Perth is one of the sunniest capital cities in the country. Cloudy days are the exception rather than the rule. A well-designed system is sized with the occasional grey day already in mind.
How Solar Panels Make Power on a Cloudy Day
Solar panels generate electricity from light, not from heat. They respond to the whole daylight sky, not only to direct beams of sun. On an overcast day, sunlight is scattered by the clouds into what is called diffuse light. Panels still convert that diffuse light into power. This is why a solar system continues to feed a home on a grey day. Panels also produce plenty of energy through Perth’s milder months as well as its peak summer.
What changes is the amount. The heavier the cloud, the less light reaches the panels. Output falls as a result. The table below gives a realistic sense of the range.
| Conditions | Roughly how much of a clear day | In practice |
|---|---|---|
| Bright, clear sky | Full output | A typical strong Perth solar day |
| Light cloud or haze | Around half to three quarters | Still a very productive day |
| Heavy overcast | Around 10 to 25 percent | Reduced, but the system keeps running |
| Rain with dark cloud | Low, but not zero | Least productive, and usually short-lived in Perth |
These figures are a general guide rather than a guarantee. Output depends on how thick the cloud is. It depends on the time of day and the system itself. The key point is that the number is rarely zero. Heavy cloud in Perth tends not to last long.
Does Rain Stop Solar Panels Working?
Rain itself does not stop a solar system. The panels are sealed, weatherproof units built to sit outside in all conditions for decades. They keep producing through a shower at a lower rate. The lower rate is because of the dark cloud that comes with rain. In fact, rain provides a system with a quiet benefit. It washes dust, pollen and salt off the glass. This keeps the panels clean. It helps them perform at their best once the sun returns. For most Perth homes, that natural rinse is a large part of why panels need little manual cleaning.
Why This Rarely Matters Much in Perth
Perth enjoys one of the sunniest climates of any Australian capital. It has long, reliably clear stretches for much of the year. Cloudy and rainy days are concentrated in the cooler months. They are usually the exception. The annual energy a system produces is dominated by the many good days rather than the few grey ones. A solar system is not judged on its worst day. It is judged on what it delivers across a year. In Perth that total is high.
It is also worth remembering that a run of cloudy days is exactly the situation a grid connection and a battery are there to smooth. On a dull day, a home draws a little more from its battery or the grid. It pays it back on the next sunny one.
What It Means for Sizing and a Battery
A properly designed system already accounts for weather. Positive Energy Solutions sizes a system around a home’s yearly energy use and Perth’s real conditions. It does not size around a perfect day. So a household is covered across the seasons rather than only in midsummer. For a home that wants to rely less on the grid during grey spells, a battery stores the surplus from sunny days. It carries the home through the dull ones. Smart energy management shifts the household’s heavier loads to the times power is lowest-cost or most plentiful.
Seasonal output is a topic in its own right. The guide on winter solar performance in Perth looks at how generation shifts through the cooler months in more detail.
How Positive Energy Solutions Can Help
Positive Energy Solutions designs each system around a home’s actual usage and roof. It performs well across Perth’s whole year rather than only on its brightest days. Every installation is completed by our accredited installers and signed off to Positive Energy’s completion standards. It is backed by a 10-year installation workmanship warranty and Positive Energy Protection, powered by Omnidian. This includes performance monitoring. A household can see exactly how its system is producing in any weather.
Frequently Asked Questions
Do solar panels work on cloudy days?
Yes. Solar panels run on daylight, including the diffuse light scattered by clouds. They keep producing on an overcast day at a reduced rate. Heavy cloud might bring output down to roughly 10 to 25 percent of a clear day. Light cloud often leaves a system still very productive.
Do solar panels work in the rain?
Yes. Panels are sealed, weatherproof units that keep generating through rain. They do so at a lower rate because of the dark cloud. Rain also rinses dust and salt off the glass. This helps the panels perform at their best once the sun returns.
Will cloudy weather in Perth hurt my solar savings?
Not significantly. Perth is one of the sunniest capital cities in Australia. Cloudy days are the exception. A system is sized around a home’s yearly usage and Perth’s real conditions. The many clear days dominate the annual total. A battery or the grid smooths the occasional grey spell.
Should I get a battery because of cloudy days?
A battery helps by storing surplus from sunny days to use during dull ones. It reduces how much a home draws from the grid in a grey spell. Whether it is worthwhile depends on the household’s usage and goals. Positive Energy Solutions works through this as part of a system design.
Design a System for Perth’s Real Weather
Solar works in Perth because the climate is on its side. A good design makes the most of it across every season. The right size and setup for a particular home is what a Positive Energy Solutions consultation is there to work out.
Talk to the local team about solar for your Perth home: request your quote from Positive Energy
About the Author
Jason Wiktorowicz
Sales Manager, Positive Energy Solutions | Perth, WA
Jason has been at the centre of Western Australia’s energy transition for over a decade. He was Orchestration Lead on Project Symphony. That is WA’s largest virtual power plant pilot. He was Stream Lead on Project Encore. He worked directly with AEMO, Western Power and Energy Policy WA. He worked to shape how distributed energy resources connect and operate on the SWIS. That work included developing and rolling out CSIP-AUS. It is now mandatory for all new WA grid connections. He also led Emergency Solar Management. It is the first program of its kind in WA. He led VPP for Schools, which provided direct market benefits through Supplementary Reserve Capacity. He also led REBAR, the WA Residential Battery Rebate scheme.
At Positive Energy Solutions, Jason leads sales with a focus on system design accuracy and long-term performance. Positive Energy Solutions installs solar and battery systems, EV chargers and heat pumps. It holds partner accreditations with Fronius, SigEnergy, iStore and SunPower.
10-year installation workmanship warranty. Positive Energy Protection, powered by Omnidian, performance monitoring included on all systems.
