According to the Solar Energy Industries Association (SEIA) Q4 2021 Report , a commercial solar panel has an average cost of $1.45 per watt in the US. You can expect a lifespan of 25 years or more when using high-quality solar panels, and their payback period can be less than 6 years with favorable local conditions.
Acquiring an asset with a useful life much longer than its payback period is an excellent investment. However, this is only true if the solar photovoltaic system is properly designed and installed. Here we will share four design tips that can help improve your ROI when using solar energy in commercial buildings.
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1) The service life of solar panels and commercial roofs must match
High-quality solar panels can last more than 25 years, and many manufacturers now offer a corresponding 25-year product warranty. To take advantage of this durability, solar panels should be used on commercial roofs that will have the same useful life. Roof replacement can be an expensive project, and the costs are even higher when you need to remove and reinstall a solar panel. Also remember that solar panels and other components can be damaged during the process and you will likely void your warranty.
Considering this, the best time to install solar panels on a commercial building is right after construction when the roof is new, or in conjunction with a planned roof replacement. The worst case scenario is being forced to replace a roof with installed solar panels, especially if they are relatively new. The additional cost of removing and reinstalling solar panels will eat up a major portion of your lifetime savings: the cost of ownership becomes much higher and your ROI is drastically reduced.
2) Solar panel layout should consider maintenance needs
Commercial roofs are often used for HVAC equipment such as cooling towers and air-cooled chillers, and they also have drainage systems and vents. If you are considering a photovoltaic solar panel, its layout must not interfere with the operation and maintenance of these systems. The maintenance needs of the roof itself must also be taken into consideration.
To optimize your roof layout, an easy solution is to work with the same engineering firm for your commercial solar project and MEP project . This will ensure that all equipment has enough space for maintenance and you will also meet the roof access requirements of local fire codes.
Ideally, the commercial solar panel should be divided into groups of panels, with sufficient spacing for maintenance. With this layout, you can easily access a specific panel or roof location if needed. On the other hand, when a commercial solar panel does not have spacing between the rows of panels, it is very difficult to reach the center.
3) Consider a reflective roof surface with bifacial solar panels
As the operating temperature of solar panels increases, their productivity drops. This loss is typically 0.5% per °C or less when using high-quality photovoltaic modules, but increases as the temperature increases. For example, an increase of 24°C in the operating temperature of solar panels will result in a drop in productivity of up to 12%.
- Solar panels tend to have a higher operating temperature on opaque roofs as they absorb more sunlight.
- By using a reflective roof surface, you can reduce the temperature of your solar panels and improve your electricity production.
It is possible to obtain even better results with bifacial solar panels, which have their photovoltaic cells exposed from above and below. This means that they generate energy with sunlight that hits them directly, just like conventional solar panels, but also with sunlight reflected from the roof.
4) Make sure the solar rack system is suitable for your commercial roof
The commercial solar array will not damage your roof as long as the racking system is compatible with its materials and structure. To achieve this, there must be clear communication between roof designers and solar designers. The roof must have sufficient structural capacity for the solar panel, especially when using a weighted racking system, which has additional weight.
Roof and solar structure materials must also be compatible, as they will remain in contact for more than two decades. You should avoid combinations of materials that present corrosion or abrasion problems.
Ballasted racking systems are the easiest to install as they are weight based without involving roof penetrations. However, ballasted racking systems are also heavier and you may experience abrasion issues in windy locations. Solar racking systems with penetrating mounts involve more work, but are best suited for commercial roofs that are constantly exposed to high winds.
