Solar panels are an excellent choice for homeowners who are sick of overpaying their energy retailer. They’re easy to maintain, up there on the rooftop; however, the environment up on the roof affects a panel’s efficiency.
The key efficiency challenges that solar panels face are shade, heat, and seasonal variations.
Understanding these factors will help you set realistic expectations and maximise performance in the design stage of your solar journey.
At Penrith Solar Centre, we know the very real effects of the environment on solar panels. We ought to. We’re the ones who fulfil warranty claims from our customers, we know what external factors affect their efficiency.
In this article, you’ll learn the following:
- How Shade Affects Solar Panel Efficiency
- The Impact of Heat on Solar Panel Efficiency
- Seasonal Variations and Solar Panel Performance
- Practical Steps to Maximise Solar Panel Efficiency in Any Condition
By the end of this article, you’ll understand how shade, heat, and time of year can impact your solar panels’ performance.
How Shade Affects Solar Panel Efficiency
Shade Affects Solar Panel Efficiency
- Solar panels need direct sunlight to produce electricity.
- When a portion of the panel is shaded, it reduces the energy output of the entire panel (and possibly the entire array).
- Even a small sliver of shadow from an overhead wire can throw off the output of an entire panel (and possibly the entire array).
Types of Shading
Clouds: Your solar panels will still produce power on a cloudy day. The sunlight hitting your panels is reduced, but your panels will still produce electricity for your home. The density of the clouds will affect how much light gets through.
Trees: Of course, this is the one most people think of when looking at their roofs. Many homes have shade from nearby trees covering a portion of the roof.
Buildings: Permanent shade from nearby buildings causes design problems for us all the time. Unfortunately, you can’t trim back branches on a building. It’s a significant obstacle that sometimes can’t be overcome.
Debris: Things like leaves, trash, and bird/batt faeces block the sunlight from hitting your solar panels. They’re obstructions that light can’t get through.
Wires: Small wires from telephone or electrical poles can surprisingly affect your solar output. Just a small shadow, from a wire or a pole, can throw off a whole array’s efficiency.
Technologies that Improve Efficiency in Shade
Microinverters:
Microinverters are small single-phase inverters mounted beneath each solar panel.
Unlike traditional string inverters, which manage power from the entire array, microinverters handle power conversion for each panel separately. This setup allows panels to work independently, meaning that if one panel is shaded, it won’t reduce the performance of the others.
Microinverters are especially useful in installations where shading may affect one part of the array (near trees or chimneys).
Microinverters also come with individual panel monitoring through the Enphase App, allowing you to see the performance of each panel and spot issues early.
DC Optimisers:
DC optimisers are devices installed on each panel to regulate the voltage output and improve system performance.
These optimisers work by adjusting the voltage of each panel individually, so if one panel’s output drops (due to shade), it doesn’t affect the others.
Power optimisers are often used alongside string inverters.
Power optimisers also enable panel-level monitoring, allowing you to see how each panel is performing in real-time.
Powerwall 3
Powerwall 3 is ideal for installations where different roof faces receive varying levels of sunlight throughout the day.
Powerwall 3 comes with three separate Maximum Power Point Trackers (MPPTs).
MPPTs are designed to continuously adjust the voltage and current to find the “maximum power point” where solar panels produce the most energy.
Each MPPT in Powerwall 3 can manage a different solar string (group of panels connected in series), allowing more flexibility in managing arrays with varying conditions across varying roof faces.
Each MPPT can adapt to its own optimal power point, meaning shading on one string on one side of the house does not significantly affect the performance of other strings.
Bypass Diodes:
Bypass diodes are small components built into the panel’s cells to redirect current around shaded sections. They activate automatically when shading occurs.
This setup helps reduce energy loss by isolating a third of the panel from the rest of the system. If you have microinverters or DC optimisers bypass diodes will be able to do that for your system. A string system will still be affected by shading, even with bypass diodes.
Bypass diodes are effective when paired with microinverters or DC optimisers for minor or temporary shading, such as shadows from passing clouds.
If you’re interested in learning a bit more about how microinverters work, you might want to check out the following article titled, Do You Need Microinverters If You Have Bypass Diodes on Your Solar Panels?
The Impact of Heat on Solar Panel Efficiency
How Heat Affects Solar Panels
Solar panels perform best in cool, sunny conditions.
Unlike sunlight, which is essential for energy production, heat itself does not help panels produce more energy.
Ideal operating conditions for most panels are around 25°C. When temperatures climb much higher, panels produce less energy even if sunlight levels are high.
Performance Statistics for High Temperatures
Most solar panels have a specification called a temperature coefficient, which indicates how much efficiency is lost for each degree above 25°C (the standard testing condition).
For example, we carry Trina Vertex S+ solar panels with a temperature coefficient of -0.29%, which is excellent. For every degree above standard testing condition (25°C), the efficiency drops by 0.29%.
If the temperature rises to 35°C, a panel with a -0.29% temperature coefficient will lose about 3% efficiency.
In extremely hot conditions, such as an Australian summer where temperatures often exceed 35°C, this efficiency loss can reach up to 5% of the panel’s rated output.
Panels with a lower temperature coefficient will perform better in high-heat environments since they lose less efficiency as temperatures rise.
Examples of Efficiency Loss in Australian Summers
On a 40°C day, a Trina panel with a -0.29% temperature coefficient might lose around 4-5% efficiency.
This means that a 450 watt panel would produce closer to 432 watts under 40°C heat instead of its full rated output.
High Temperatures Can Increase Wear on Solar Panels
Prolonged exposure to high heat can cause thermal expansion, and that stresses materials in the panel, the glass and metal.
Over time, repeated heating and cooling cycles can cause micro-cracks in solar cells, gradually reducing panel efficiency and lifespan.
If you’re interested in learning a bit more about the Trina Vertex S+ solar panels, you might want to check out the following article titled, Why We Install Trina Vertex S+ Solar Panels.
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Seasonal Variations and Solar Panel Performance
Summer:
Australia’s summer season brings longer daylight hours, up to 14 hours of sunlight on some days, which provides more opportunities for solar panels to generate energy.
The sun is higher in the sky during summer, which increases the intensity and directness of sunlight on solar panels.
Summer production can sometimes exceed household energy needs, which creates a surplus that can be stored in batteries or fed back to the grid.
Winter:
During winter, daylight hours are significantly shorter, sometimes around 10 hours or less, limiting the time available for energy generation.
The sun sits lower in the sky, so sunlight reaches panels at a lower angle, which can reduce the overall energy capture. As it sits lower in the sky, there can be seasonal shadows from nearby treetops or other obstructions.
In southern parts of Australia, where winters are cloudier and rainier, the decrease can be more pronounced.
Lower winter output means that households relying heavily on solar may need energy stored from batteries.
If you’re interested in learning a bit more about how weather affects your solar panels, you might want to check out the following article titled, How Does The Weather Affect Your Solar Panels?
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Practical Steps to Maximise Solar Panel Efficiency in Any Condition
Clean Panels Regularly:
When properly installed, solar panels are self-cleaning with the help of rainwater. But parts of Australia are dry and don’t receive much rain. If that’s the case, clean your solar your panels at least twice a year to remove dust, pollen, bird droppings, and other debris that accumulates on the surface.
In dry or dusty areas, consider cleaning panels more frequently, as dust can build up faster and block sunlight. Cleaning panels can improve efficiency if there is significant dirt buildup.
Use a hose with gentle pressure. Avoid abrasive materials that could scratch the glass. Or contact Penrith Solar Centre for an inspection and cleaning.
Inspect for Physical Damage:
Regularly inspect panels for any visible cracks, chips, or scratches on the surface.
Damage can occur due to weather conditions, fallen branches, hail, or other physical impacts, which can reduce the panel’s ability to produce power.
If you notice any damage, schedule repairs or contact your solar installer for further inspection and advice.
Install a Solar Monitoring System:
A solar monitoring system allows you to track the real-time performance of each panel or the overall system, depending on the type of system.
These systems provide data on energy production, system voltage, and any drops in efficiency.
Monitoring helps you identify issues quickly, such as shading, dirt buildup, or component malfunctions, which can reduce energy output.
Some monitoring systems are mobile apps, so you can check performance and receive alerts for any dips or faults, even when you’re away from your home.
Design the Ideal Panel Position:
In Australia, position panels strategically to maximise sunlight exposure throughout the day.
Consider an east/west split to capture more sunlight in the morning and evening.
Consider the angle of the panels. A tilt angle around 20-30 degrees is generally ideal in Australia, though optimal angles vary by location.
Avoid placing panels in locations where they may be obstructed by trees, buildings, chimneys, or other things.
Plan the installation layout carefully, taking into account any future changes, like tree growth, to prevent shading over time.
Use Microinverters or Power Optimisers:
Microinverters and power optimisers improve performance in partially shaded conditions by allowing each panel to operate independently.
Microinverters prevent one shaded panel from reducing the output of the entire system.
Power optimisers adjust voltage from individual panels, helping to maintain consistent power output across the system even if some panels are shaded.
These technologies are particularly useful if your installation site has unavoidable shade from nearby structures or trees.
Battery Storage:
Battery storage systems like Tesla Powerwall can hold the day’s energy, providing power during the evening.
By storing daytime energy, households can rely less on the grid and enjoy consistent solar power through seasonal fluctuations.
Battery storage is especially beneficial for households that use a lot of energy in the evenings when solar production has stopped for the day.
Batteries are particularly valuable in areas with limited grid access or frequent weather variations.
If you’re interested in learning a bit more about shopping for a solar system, you might want to check out the following article titled, 6 Mistakes to Avoid When Buying Solar.
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I sky with my little eye solar panel efficiencies.
Now you know a bit more about solar panel efficiency. It depends on several factors, including shade, heat, and seasonal changes. Installing the right technology and keeping an eye on the system will reduce losses in efficiency.
By understanding some of these challenges and solutions, you can maximise your system’s performance and do some good for the planet.
At Penrith Solar Centre, we’re here to guide you through your solar journey with education. We’re experts in solar panel installations and we’re sure to help you find the exact right equipment for your unique and customised solar system. It’s what we do.
If you’re interested in learning a bit more about the process of choosing components for your solar system, you might want to check out the following article titled, How to Shop for a Solar System.
