Contact Us

Request Your Quote


Winter Solstice in Perth: A Sun-Powered City

The Winter Solstice is here, bringing the shortest day of the year. And while some people celebrate by taking an early morning skinny dip in the icy waters of the Indian Ocean, we at Positive Energy are busy getting ready for the days’ solar & battery installations ahead. Fully clothed, of course.


In the depths of Winter, you might also see solar production taking a dip and a shrinkage in yield. But not as much as you might think… Even on the shortest day of the year, Perth’s solar production remains remarkably robust.

To prove it, let’s dive into the data about solar panel performance during the Winter months here in Perth; the world’s sunniest capital city.

Solar Production: Perth vs. London

To illustrate Perth’s solar advantages, let’s compare its year-round solar production with that of London. London, known for its overcast skies and shorter daylight hours, offers a stark contrast to Perth’s sunny disposition.

Key Comparisons:

  • Annual Sunlight Hours: Perth enjoys approximately 3,200 hours of sunshine annually, while London averages around 1,400 hours. This significant difference means Perth has more than double the sunlight exposure compared to London.
  • Winter Performance: In winter, Perth’s solar production remains robust due to its clear skies and mild temperatures. Conversely, London’s winter solar production drops significantly due to frequent overcast conditions and shorter daylight hours.
  • Seasonal Variability: While both cities experience seasonal variability in solar production, Perth’s consistency in sunny days ensures a more stable year-round performance.

    The comparison graph clearly demonstrates that Perth’s solar panels outperform those in London across all months except two. Even in the middle of Winter, solar production in Perth is nearly as good as England in Summer!

Perth Solar Production in Winter

When winter rolls around, some people assume that solar panels are not worthwhile. However, this is a misconception, especially in Perth. Known for its abundant sunshine, Perth boasts more sunny days than any other capital city on the planet, ensuring that our solar panels continue to perform exceptionally well even during the winter months.

The Winter Solstice has just passed recently, with the sun rising at 7:16am and setting at 5:20pm. Despite fewer daylight hours, Perth’s solar panels still generated an impressive amount of energy. This is due to two key factors:

  • High Solar Irradiance: Perth receives ample sunlight even in winter. The clear skies and high solar irradiance levels ensure that solar panels produce a significant amount of power.
  • Mild Temperatures: Cooler temperatures actually improve solar panel efficiency. Unlike in summer, when extreme heat can reduce efficiency, winter’s milder climate helps panels operate efficiently.

Let’s take a look at some real-world solar production graphs from our customers this past week.


6.6kW Canadian Solar panels split East & West + 5kW Fronius inverter + 11kWh BYD battery

Daily Yield: 16.6kWh. Self-sufficiency: 100%. Savings: $4.27


10kW SunPower solar panels split NE & NW + 5kW iStore Hybrid inverter + 15kWh iStore Battery

Daily Yield: 35.7kWh. Self-sufficiency: 81%. Savings: $9.40


13.2kW Canadian Solar panels split North & West + 10kW Sungrow Hybrid inverter (with 1.5kW export limit) + 19.2kWh Sungrow battery

Daily Yield: 35.9kWh. Self-sufficiency: 96%. Savings: $9.98

As you can see, even on the shortest days of the year, solar panels in Perth produce substantial energy and deliver significant savings.

What about cloudy days?

Let’s take a look at one more system on an overcast day. This is an interesting one…


With low solar production and high power consumption, on this day there was very little excess solar power to send to the battery. Yet the battery still reached 100% State-of-Charge. How…?

Despite a miserable day for solar production, our customer was still able to achieve significant savings by taking advantage of ‘Off-Peak’ and ‘Super Off-Peak’ tariffs on the Synergy Midday Saver Plan.

  • The day began with an empty battery depleted from the night before. Fortunately, ‘Off-Peak’ grid power purchased overnight between 9pm – 9am is at a discounted rate of 22.55 cents/kWh = a 27% saving.
  • After 9am, savings jumped even higher with ‘Super Off-Peak’ grid power costing only 8.2 cents/kWh = a 73% saving!
  • This ‘Super Off-Peak’ grid power not only makes up the shortfall in solar production, but can also be used to top-up the battery on cloudy days. You can see in the graph above, at midday the battery begins Force Charging at full speed. By 2:40pm the battery reaches 100% State-of-Charge.
  • From 3pm – 9pm, we enter the expensive Peak tariff window when grid power costs 51.25 cents/kWh. Not to worry though! Thanks to the Solar & Battery system, the customer was completely self-sufficient during these hours and avoided purchasing any expensive grid power.

The Result:

On this day, the customer consumed 34.7 kWh of energy in total. Without a Solar & Battery system, this energy would have cost $10.69 on the regular ‘Home A1’ tariff.

Instead, thanks to a combination of Solar + Battery + Synergy Midday Saver Plan, the customer’s daily energy cost was only $2.38; a 77.7% saving on a cloudy day. Not so miserable after all!

Embrace Winter with Positive Energy

Why wait for Summer to start saving? The best time to install solar is now! Contact us today for a tailored quote to suit your needs.

At Positive Energy, we’re committed to providing reliable, high-performance solar and battery solutions, along with expert advice on how to maximise your savings.


Solar and Battery Upgrade | Port Kennedy

We recently upgraded & expanded a system for our customer in Port Kennedy with 4.5kW of extra solar panels, new Fronius Hybrid inverter and 11kWh BYD Battery.


Solar and Battery Upgrade | Secret Harbour

We recently expanded & upgraded an existing system in Secret Harbour with an extra 9kW of solar panels + new 10kW Sungrow Hybrid inverter + 12.8kWh Sungrow Battery.

Contact Us

Give us a call today and one of our friendly and knowledgeable energy consultants will be able to assist you with your enquiry.


Level 1, 59 Howe Street Osborne Park, Perth 6017


Request Your Quote