Finding the Optimal Layout for a Commercial Solar Array: Design Tips

Michael Tobias
February 8, 2022
4 Minutes Read
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    KEY TAKEAWAYS

    - Two commercial solar arrays of the same size can have very different results, depending on their layout.

    - Shaded roof areas must be avoided, since they greatly reduce the electricity output of solar panels.

    - Solar panels are easier to install on flat roof sections, since there is no need to drill holes for the mounting system. You can simply use ballast weights to hold the system in place.

    - Commercial roofs are often shared with mechanical equipment, and you must leave enough space around these units for maintenance purposes.

    - Larger solar panels with 72 cells (or 144 half-cells) are recommended for commercial roofs, since they save on racking and installation costs.

    - Planned expansions and renovations should also be considered when designing the layout of a solar array, to avoid areas where solar panels can be an obstacle.

    Inflation many products and services in the US, and this includes electricity prices. According to the US Energy Information Administration, home electricity prices increased by 6.1% in the residential sector between November 2020 and November 2021, and by 7.6% in the commercial sector. However, when homeowners and businesses generate their own electricity with solar panels, the effect of price hikes can be minimized or avoided completely.

    When the layout of a solar array uses your roof as efficiently as possible, your power bill savings are increased. However, this can only be achieved with a professional assessment and design. A suitable layout can also help you save on installation costs, which means you get a shorter payback period and higher ROI.


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    Here we will discuss the main factors to consider when designing the layout for a commercial solar array. Two buildings can have the same number of panels, but the results can be very different if one of them uses roof space more efficiently.

    1) Avoiding Shadows is the #1 Priority

    shaded solar panels

    The electricity output of solar panels directly depends on how much sunlight reaches their surface. When panels are installed in the shade, you’re wasting most of their capacity and the dollars used to purchase them!

    Avoiding shadows may seem simple, but there’s a catch. The sun’s position in the sky is always changing, and this depends not only on the hour but also the current season. The same part of your roof can be very sunny or fully shaded, depending on when you look. Solar engineers use design software that simulates sunlight and shading throughout the year, so they can find the best areas of your roof.

    Generally, shading is not an issue for large commercial buildings in suburban or rural locations, where there are few obstacles around. However, avoiding shadows is critical when installing solar panels on buildings surrounded by taller structures and obstacles.

    2) Installing Solar Panels on Flat Commercial Roofs Is Simpler

    The type of racking system required by your solar panels depends on the roof material and slope. Many commercial buildings have flat and spacious roofs, where solar installations are much easier. Solar panels can use a ballasted racking system, which simply uses heavy bases to hold them in place. On the other hand, when solar panels are mounted on sloped roofs, you need to drill holes to attach their mechanical supports.

    If you have a commercial roof with both flat and sloped sections, you can make the installation easier by prioritizing flat areas. Maintenance also becomes simpler: inspecting and replacing solar panels is easier when technicians can reach them without walking on steep surfaces.

    3) Leave Enough Space Around Mechanical Equipment and Other Components

    rooftop hvac

    Generally, solar panels will not be the only devices using a commercial roof. You also need space for mechanical equipment such as cooling towers and roof vents, considering their maintenance needs. Keep in mind that technical personnel must access these units regularly, often carrying tools, and solar panels should not get in the way. You also protect the panels by keeping them away from other equipment, since they are less likely to be damaged by a falling tool or part.

    The layout of a commercial solar array must also have proper spacing for its own maintenance. In this aspect, solar panels are less demanding than other power generation systems. However, they need regular cleaning and occasional inspections.

    4) Larger Solar Panels Save on Racking and Labor

    Solar panels come in many sizes, but 60-cell and 72-cell modules are the most common. Their specifications and dimensions vary by manufacturer, but both types have roughly the same width, while 72-cell panels are around 20% taller. Also consider that many brands have started to use half-cells with a more efficient design: they have 120 or 144 half-cells instead of 60 or 72 normal cells, but overall sizes are almost the same.

    Solar panels with 72 cells or 144 half-cells save on installation costs, for two main reasons: Since they have the same width as 60-cell panels, the amount of racking used per panel remains constant. However, since the total number of panels is reduced, racking and labor costs are optimized.

    5) Planned Expansions and Renovations Must Be Considered

    High-quality solar panels have a service life of 25 years or more, which means you will save on power bills for a long time. However, you should also use a roof area that will not be modified in a long time, or otherwise you will be forced to relocate the photovoltaic array. This represents an extra cost, which you can avoid by simply picking a roof area that will not be renovated or modified.

    Tags green energy renewable energy Solar Power solar energy commercial solar

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