Solar panels are a great addition to any home for those who want to save on electricity bills with an all-natural power output. However, solar panel shading can cause issues, and not only for the shaded modules and solar cells.
If you have (or are considering investing in) solar panels for your property, it’s important to understand the way in which shade can impact the overall efficiency of a solar array and system.
In this article, we’ll cover everything you need to know about solar panel shading, from the role of solar PV modules and power optimisers to the simple ways to keep your system in good working condition.
TL;DR:
- The best solar system is one that enjoys full sun, as shading creates an imbalance between solar panels in terms of energy production.
- How well a shaded module produces electricity depends on the quality of your solar photovoltaic, or solar PV, system, and on the maintenance processes in place.
- In order to maintain maximum power output without consistent direct sunlight, you’ll need to mitigate solar panel shading by removing nearby obstacles that cast shadows.
Understanding Solar Panel Efficiency
Solar panels work by collecting solar power through solar cells, devices that convert sunlight into electricity. Full sun exposure is recommended to maximise power output; however, in some cases, solar shading is unavoidable.
Solar panel efficiency depends on several factors including the total number of panels, the location, the weather conditions, the recency and condition of the system, and number of shaded vs unshaded cells.
While modern technological advances have led to a greater tolerance for shade in most solar systems, even minimal shading or a few shaded cells can have an impact.
What Happens If One Solar Panel Is Shaded?
Shading on solar panels—whether from passing clouds, bird droppings, or bat droppings—is just part of life for Queensland solar panel owners. Gandis Utari from Sunrays Power says that while some shading here and there isn’t a big deal, long-term exposure to partial shading can cause trouble.
“Where some PV panels are in full sun and other panels experience dynamic or static shading, it may be that the other panel output mismatches the rest, creating an imbalance and decreasing effectiveness of the system,” Utari said.
“Even if a shaded module produces electricity, which may be possible in a case of minimal shading, the shade will limit solar irradiance and ultimate power output.”
The Science Behind Solar Panels and Shading
Solar panels convert sunlight into electrical energy through PV panels, a process that is disrupted by shading. This causes multiple concurrent problems, as the energy from a solar module in sunlight will turn into heat in a shaded PV module, which can damage the cells.
When sunlight fails to hit an entire panel of solar cells, energy from the exposed cells can turn into heat in the shaded ones. Over time, this can affect efficiency and even create hotspots that, if hot enough, can damage the panel. Not ideal!
For older systems, this was a real system killer – in fact, it still affects modern panels on the cheaper end of the scale. Depending on your solar panel and inverter, a single shaded panel could even prevent your entire system from working. Older technology just couldn’t handle the voltage drops caused by shade, leaving inverters struggling to keep things efficient.
The good news is that things have come a long way – most modern solar panels and smarter string inverters are much better equipped than past models which were not able to deal with shading and unable to keep your system running smoothly.
Solar System Components and Shading
Cheaper solar panels are more vulnerable to heat problems. While modern technology has made leaps and bounds, not all panels are created equal. Budget panels might come with lower-quality materials or outdated bypass diodes, which means they’re more likely to struggle with partial shading. Having even one panel partially shaded can result in the entire system being less efficient—or in some cases, stopping altogether.
Essentially, the old saying rings true: you get what you pay for.
Technological Advancements in Solar
The latest solar technologies, such as micro-inverters and power optimisers, help to combat the effects of shading and maximise power output.
Additionally, higher-quality panels and inverters are built with better shading tolerance in mind, and often have advanced technology built in – split-cells, multiple bypass diodes, string inverter MPPT tracking, amorphous thin-film, and bi-facial technology, for example – which help keep the system running efficiently even in cases of partially shaded cells.
During periods of less efficient solar generation, batteries also help consumers better manage energy loads; however, due to their cost, batteries are only really cost-effective if:
- You want to consume energy when sunlight is minimal
- You have an electric vehicle (EV)
- You want to maximise green energy usage without relying on the grid
The challenge with batteries is that battery repayments are oftentimes greater than the savings you receive. Especially, for clients that do not make full use of their battery through higher energy loads. For those that own an EV, having a battery can really help owners have peace of mind and allow them to charge overnight without pulling from the grid. Learning to manage a household energy load in order to get the benefit of batteries requires repeated adjustments and knowledge of your own consumption patterns.
The Role of Inverters in Managing Shaded Panels
Micro-inverters
Micro-inverters are installed directly underneath each solar panel, sometimes serving one panel or a small group (e.g., two or four panels per micro-inverter, depending on the model). All the connected panels operate independently, handling the DC-to-AC conversion at the source. Unlike traditional string inverters, where the lowest-producing panel limits the performance of the entire string, micro-inverters maximise solar output from each panel. This makes them ideal for roofs with shading issues or complex layouts with panels facing different directions.
Optimisers
Power optimisers are add-ons installed at each solar panel that work together with a central string inverter to enhance its efficiency. Power optimisers handle Maximum Power Point Tracking (MPPT) at the panel level, maximising power output from each panel, even where shaded cells present issues. They also enable panel-level monitoring, so you can track panel performance individually.
Power optimisers are a great choice for systems with panel mismatches (for example, differences in orientation, or pitch), as they minimise energy losses without needing micro-inverters for every panel. Optimisers are less expensive than micro-inverters, but are more expensive than just purchasing a string inverter. Additionally, as optimisers work in conjunction with a string inverter, the overall system performance, while more efficient, is still limited to the string inverter’s overall capacity. It is essential to install a good string inverter if you choose to go with this option.
String Inverters
An inverter with an MPPT (Maximum Power Point Tracker)—or multiple MPPTs—is designed to optimise the energy production of your solar system, even in less-than-ideal conditions like partial shading. Essentially, an MPPT continuously adjusts the voltage and current from your solar panels to ensure the system operates at its optimal power point, even if panels are shaded due to differences in orientation, dirt, or degradation.
Even when one string in your system is shaded, the MPPT ensures that the unshaded modules continue to produce as much energy as possible. Advanced inverters with multiple MPPTs take this a step further, allowing different strings of panels to operate independently, which is particularly beneficial for systems with multiple orientations that receive dynamic shading. Without MPPT, inverters struggle to convert this power efficiently, and if the output power from the shaded panels or string were to fall below the inverter’s minimum threshold, the section could stop working altogether.
While all newer inverter models come with MPPT tracking capabilities, premium string inverters are more advanced. A premium string inverter will still cost less than power optimisers or micro-inverters, but may not deliver as much electricity if the roof is heavily impacted by shading for long periods of time throughout the day.
Solutions to Minimise Shading Impact
To pass a solar system audit, the system must be able to efficiently and safely produce electricity for your home, which is not possible if excessive shade affects the system, for example, due to chimneys, antennae, vents, pipes, trees, or even taller buildings nearby.
To prevent a failure, tackling solar shading issues prior to installation is crucial. This may mean moving antennae or trimming trees to optimise solar production. Otherwise, shaded PV modules will affect the efficiency of the entire solar panel in shade, decreasing the return on investment.
However, where sources of static shading (e.g. a tall apartment building) or dynamic shading (e.g. a neighbour’s trees) are beyond your control, careful placement of solar panels and implementation of alternative strategies (e.g. optimisers, micro-inverters, or other panels with smart energy load and timing management) can help mitigate losses caused by solar panel shading. However, these solutions can be expensive, so it’s important to weigh the costs against the long-term benefits of maximising efficiency at installation.
The good news is, a knowledgeable solar panel installer armed with the latest solar design software can ensure the system complies with audit standards while maintaining its efficiency and cost-effectiveness and generating maximum power.
Regular Maintenance and Monitoring
Routine cleaning and monitoring of solar panels, including the detection and management of shading issues, is key to ensuring that they operate at peak efficiency.
Important processes as part of regular maintenance include:
- Checking production curves through your monitoring app or inverter
- Trimming trees and hedges that create shade over your solar PV system, whether it affects singular or multiple solar panels
- Clean panels with a non-pressurised hose. Do not climb onto the roof, and avoid using cleaning liquids or any harsh scrubbers, like brooms.
- Gently wipe stubborn spots (e.g. dried-on bird droppings) with a wet microfibre cloth. Avoid placing pressure on panels.
If you are taking all of these steps and still finding that your solar power output voltage is not what you would like it to be, our team of expert solar panel manufacturers can help!
Case Study: Overcoming Shading Challenges
Installing solar panels in a situation with high risk of a shaded module, or even just one cell, can be complex, requiring an in-depth understanding of how shading solar panels also affects unshaded modules and decreases the output power from an entire string.
In one particular case study, a Sunrays Power client needed a dynamic shading solution where a neighbour’s trees were causing shaded cells. Watch below for our solution.
If you’re preparing to have solar PV modules installed on your property, now is the time to consider all the factors that could lead to shading on solar panels, affecting your other PV modules and the solar array as a whole.
Monitoring the efficiency of any panels installed on your roof and investing in regular maintenance is key to keeping your system in good working order over its lifespan – which, with any luck, could be over 25 years.
How Sunrays Power Can Help
Sunrays Power has extensive expertise in the creation and delivery of tailored solar solutions. Drawing on our years of experience as solar installers, we assist homeowners in addressing shading and other efficiency issues, installing solar panels in a way that maximises system output. Don’t let solar panel shading work against you – let us make sure your system work harder.
For a personal assessment of your solar needs and a plan that maximises your output voltage, contact the team at Sunrays Power – we’re here to help you get the best out of each solar panel array, no matter how many cells are affected by solar panel shading.
Call us today on 1800 720 719 for an obligation-free chat.
