Overcoming shading issues in your new solar installation

Shading is a common concern when it comes to installing solar panels, especially in urban or heavily vegetated areas. While you might be eager to tap into the power of the sun and save on your energy bills, shading can present a hurdle that affects your solar system’s efficiency. But fret not, as there are various strategies to overcome this issue.

How Shading Affects Solar Production

Solar panels are generally wired in series to form a “string.” The electricity generated by each panel flows through the whole string before reaching the inverter that converts it to a usable AC current. In traditional systems using string inverters, if just one panel in the string is shaded, it can drastically reduce the performance of the entire string. This means even minor shading can significantly lower the system’s overall performance.

To better understand this, consider a string of Christmas lights. Each light bulb on the string is akin to a solar panel in a series connection. When all the bulbs are fully lit, the string shines brightly. However, if even one bulb goes out or dims, the entire string’s brightness is affected. Similarly, when a solar panel is shaded, it impacts the performance of the entire string, reducing your system’s overall energy output.

Common Sources of Shading

Shading is not just an issue in densely populated urban environments but can also occur in suburban or rural settings. Here are some typical culprits:

• Trees and Foliage: Large trees, especially evergreens, can cast long shadows at different times of the day.
• Nearby Buildings: Multi-story buildings or even single-story structures with unique architectural features can cause shading.
• Chimneys and Vents: Smaller objects on your own roof can sometimes be the most easily overlooked sources of shading.
• Power Lines and Poles: Overhead lines, especially in rural areas, can also contribute to shading issues.

Understanding the sources of shading can help you take corrective actions more effectively.

Strategies to Overcome Shading

Option 1: Use the Right Roof Sections

If you have a multi-faceted roof, using the sections that are less prone to shading during peak sunlight hours can be beneficial. Your solar provider can conduct a thorough site assessment to identify the ideal areas for panel placement.

Option 2: Remove Obstructions

Another way to combat shading is to address the source directly by trimming or removing obstructions. If your property has large trees that cast shadows, consider pruning them. If a built structure like a shed or a neighbouring building is causing the issue, it might be more challenging to find a solution, but sometimes small adjustments can make a significant difference.

Option 3: Microinverters

Modern technology offers solutions like microinverters and power optimisers, which are designed to mitigate the shading issue.

Microinverters offer a high-tech solution to the shading problem by allowing each solar panel in the array to operate independently of the others.

With microinverters, each panel has its own small inverter attached directly to it. This device converts the panel’s DC electricity to AC right at the source, allowing the panel to function independently. Therefore, if one panel is shaded, the rest of the panels are unaffected and continue to operate at their maximum efficiency.

Microinverters replace the need for a standard or hybrid inverter but do come at a cost. Generally, you can expect to pay around $150 to $250 per microinverter (one per panel), depending on the brand and specifications. For an average-sized solar system of about 6 kW, which would typically include around 18 to 20 panels, the additional cost could range from $2,700 to $5,000.

Option 4: Power Optimisers

Power optimisers offer another technological avenue for mitigating the impact of shading. Unlike microinverters, power optimisers don’t entirely replace the function of a central inverter. Instead, they work in tandem with it. These devices are connected to each individual solar panel and optimise the DC electricity that the panel generates before it’s sent to the central inverter for conversion to AC. In essence, they pre-condition the electricity, adjusting the voltage and current to maximise the energy harvest from each individual panel.

Because each panel’s performance is optimised, a shaded or underperforming panel has less impact on the system’s overall performance. This offers a good middle ground between traditional string inverters and microinverters, combining the benefits of individual panel optimisation with the cost-effectiveness of a central inverter.

The cost for adding power optimisers to your solar system falls between traditional string inverters and microinverters. Generally speaking, a power optimiser could cost you around $50 to $100 per unit. If you have an average-sized 6 kW system with 18 to 20 panels, this means an additional cost ranging from $900 to $2,000.

Deciding What To Do: Calculating ROI

Before making a choice between microinverters, power optimisers, or sticking with a traditional setup, it’s crucial to consider the return on investment (ROI). ROI is essentially how long it will take for the added benefits to outweigh the additional costs. One way to assess this is to look at the percentage of shading on your panels and calculate how much energy loss you could potentially recover by using microinverters or optimisers.

For instance, if your traditional system loses 10% of its output due to shading, and a microinverter system could recover half of that, you’re looking at a 5% increase in energy production. If this 5% amounts to, say, $100 savings per year, and the additional cost of the microinverters is $3,000, it would take 30 years to break even—perhaps longer than the lifetime of the panels. In such cases, it might be more cost-effective to trim obstructions or reposition the panels.

This is something your Arkana solar expert will help you work out and decide prior to installation.

Conclusion

In summary, overcoming shading issues for your solar installation isn’t just a challenge; it’s an opportunity to maximise your system’s efficiency and, by extension, your energy savings. Whether you’re dealing with shadows from trees or neighbouring structures, options like optimal roof section use, obstruction removal, and technological solutions like microinverters and power optimisers offer effective paths forward. Shading is also something to continue monitoring as time goes on, after you get your system.