Solar-Ready Buildings Part 1: How can you design your new building for solar?


While almost any existing building with the right attributes can be retrofitted to integrate a solar system, designing a new building with solar already in mind can be a very cost-effective way of ensuring the easiest installation. Our team at PowerFlex has developed custom solar and solar-plus-storage solutions for corporate clients across the U.S. In this blog, we’ll discuss the key variables to consider when planning a building that will incorporate a PV system.

Hosting capacity

A solar developer will first determine if the property is in an area that can export solar energy back to the grid by checking the utility and AHJ restrictions. Area capacity maps are available for some utilities and can confirm the circuit's remaining capacity, while the utility websites will often report the interconnection limit.

Building orientation

In the northern hemisphere, solar panels will receive the most solar exposure when tilted to the south. On flat roofs, a space-constrained building that runs long from east to west will enable longer south-facing rows and limit the need for additional rows and row spacing. On the other hand, panels on pitched roofs are mounted flush, and their tilt will be subject to that of the roof. This means that the ideal pitched rooftop has a large south-facing surface with minimal tilt.

Shading Factors

Shading from neighboring buildings, trees, and other tall structures could reduce the available roof area for the desired PV system; if possible, situate your new building so it may have a sizable unencumbered solar resource. Be thoughtful of the proximity at which growing trees are planted from the building, particularly to the south of the array. Additionally, avoid self-shading by limiting variations in your new design’s roof height and consolidating roof equipment and vents onto the northern side of the roof. PowerFlex’s advanced simulation software considers shading, and in-person site visits allow the team to survey the ideal roof space for the solar array more precisely.

Roof Type

Installing a solar system on top of a new roof surface is ideal for synchronizing the roof’s lifespan with that of the array. We recommend using roofing membranes, such as TPO or EPDM, that have extended life expectancy and energy-saving attributes. PowerFlex has experience advising and coordinating solar installation to occur simultaneously with the roofing process. We will work with the roof management team to ensure solar deployment will be within the roof warranty and up to code.

Structural Factors

The roof's necessary structural capacity should be designed to withstand additional load ranging from 3 to 6 pounds per sq. ft. (psf)  to accommodate solar. PowerFlex typically installs a ballasted racking solution on flat roofs. The amount of ballast required depends on the local wind speed, building height, parapet height, size of the arrays, and ideal panel tilt. The weight of this system is typically 4-6 pounds psf on a distributed basis for flat roofs. In certain scenarios, roofing attachments can be used to reduce the amount of ballast required. For example, point loads are between 50 and 350 lbs. depending on the racking system choice and configuration.For metal seam roofs, the panels are typically attached using seam clamps and rails without additional ballast. The weight of the system is typically 3-4 psf on a distributed basis for metal and corrugated roofs.

Electrical Factors

The customer should design their electrical gear to accommodate the addition of solar without utility upgrades. PowerFlex will provide an approximate maximum required overcurrent protection (OCP). A line side connection is typically preferred, and the switchgear can easily be configured to streamline this installation. The client can also run conductors and conduit from the main distribution panel to a disconnect on the roof; this will allow the system to be interconnected on the roof and minimize operations' impact by avoiding shutdowns and indoor work. No matter the existing electrical configuration, PowerFlex is accustomed to completing this work and can provide specifications for the customer to guide this design.From development to execution and asset management, PowerFlex has been providing reliable solar solutions to clients across the U.S. With more than a decade of industry experience, our finance and engineering teams work closely with the clients to maximize the project benefits. To learn more and receive a free solar assessment, contact us today.