Commercial Rooftop Solar

Let's make it work. 

Call our Commercial Rooftop Specialist
Melissa Carr
(310) 623-7080

What is your rooftop challenge?

Commercial rooftop solar projects offer an excellent financial return in most markets.


One reason is that when solar modules are rooftop mounted, they use the building structure and electrical system to minimize additional materials that would normally be required for ground mount and carport solar facilities. Net metered rooftop projects therefore bring a desirable financial benefit that outweighs most challenges.

Types of rooftops

The variety of rooftops found on commercial buildings can prove difficult for any rooftop solar engineer and contractor. No matter the challenge, Blue Oak is adamant about bringing the original roofing company into the project to ensure the rooftop warranty honored. This step is essential to ensure continuous rooftop warranty coverage.

Composite or built-up rooftops are common. These are often the easiest to work with because the material is readily available.

rooftop Solar Systems

Standing seam metal rooftops can be ideal for attaching commercial solar arrays because rooftop penetrations are not required to secure the array into place. We use a seam clamp to mechanically fasten the metal roofing to the solar array.

Commercial Rooftop Solar Panels

The modern roof membrane is generally a single ply membrane made of a variety of different materials. These single ply membranes can be excellent for rooftop solar arrays because they are long-lasting and easy to repair and maintain over time.

commercial solar rooftop array

Working with a rock or gravel ballasted rooftop can be a challenge. In many locations the rocks will need to be removed to allow for the solar array mounting system to make positive contact with the roof surface. If the rocks are not moved, they will be pushed into the membrane and provide locations for water settling and intrusion.

•	Gravel Ballasted Commercial Solar Rooftop

What's your rooftop challenge?

As far as rooftops go, we’ve seen it all.

Blue Oak is skilled with different types of roof membranes and sensitive to building owners’ concerns. While many commercial solar installers boast of fully-ballasted systems that avoid rooftop penetrations, we have rarely seen successful rooftop solar systems without some positive attachment and anchoring to the structure.

When engaged in engineering and installing your rooftop solar project, Blue Oak Energy will carefully design your system to withstand wind events, thermal expansion and contraction, and significant rainfall.

Our Rooftop Solar Projects

Southern California Edison and ProLogis

  • Southern California
  • 90 MW Aggregate
  • Southern California Edison (SCE)

From 2010-2012, 90MW was successfully deployed on 25 commercial solar rooftops in southern California. Part of the initiative includes the largest single solar PV rooftop in 2011 in the U.S., with a DC nameplate rating of 8.55 MW on a 1.3M square foot building.

Read Case Study

Bay Area Rapid Transit (BART)

  • Richmond, CA
  • 160 kW

This solar rooftop system is on top of the BART maintenance shop building in Richmond. The system is completely ballasted and did not penetrate the rooftop's membrane, which was a strict requirement from the client.

Bay Area Rapid Transit (BART)

  • Hayward, CA
  • 255 kW

This rooftop solar system is mounted on top of the BART maintenance shop in Hayward. The building roofs were at different heights, with the center portion of the roof being about 10' higher than either side, so shading influenced the final array layout.

Holliston Solar Facility

  • Pasadena, CA
  • 238 kW

This solar rooftop facility was part of the California Institute of Technology sustainability program. The solar modules are supported by an innovative space frame structure to allow for wide spans using fewer columns.

Golden 1 Center

  • Sacramento, CA
  • 708 kW
  • Sacramento Municipal Utility District (SMUD)

Golden 1 Center is a multi-purpose indoor arena and the home of the Sacramento Kings professional NBA basketball team. This 708kW rooftop solar electric system was installed during the arena's original construction in 2016. This solar facility reduces the building's electrical energy import from the SMUD utility grid. The Golden 1 Center is in the top 10 largest solar arrays at professional sports stadiums in the United States according to the list maintained by the Solar Energy Industries Association (SEIA).

USVA – San Diego

  • San Diego, CA
  • 250kW
  • SDG&E

This distributed generation rooftop solar electric project is an excellent example of what occurs to work around existing equipment and facility requirements. The project was specifically designed to meet the stringent U.S. government facility requirements. Blue Oak Energy provided the electrical and mechanical engineering services for this project and provided support during initial bidding, through final construction close-out.

Sony Picture Studios

  • Culver City, CA
  • 250 kW

This rooftop solar system was designed to offset Sony's high energy consumption on their movie studio sets. This complex roof layout and decking required careful electrical and structural design.

Los Angeles Steel

  • South Gate, CA
  • 800 kW

Blue Oak Energy delivered complete construction plans, installation training and commercial solar energy system startup to help the installing contractor deliver an operational system.

Walgreens Distribution Center

  • Woodland, CA
  • 1.15 MW

This project includes a flush mount system on a standing seam metal roof and a tilted racking system on a flat roof. Each system had a dedicated inverter to optimize the energy harvest.

Walmart Program

  • Southern California
  • 10 MW Aggregate

This 500 kW system in Glendora, CA is typical of Wal-Mart’s multi-site solar initiative. Blue Oak Energy provided engineering and on-site construction management on 22 distinct sites.

Read Case Study

House Foods America Corporation

  • Garden Grove, CA
  • 215 kW

House Foods is one of the largest fresh tofu and frozen food producers in the United States. The rooftop solar array adds clean energy to this state-of-the-art processing facility.

Google Headquarters

  • Mountain View, CA
  • 1.9 MW

This extensive and architecturally complex campus required a forward-thinking design solution, including both rooftop and carport PV arrays.

Read Case Study

FedEx Ground Facility

  • Woodbridge, NJ
  • 2.42 MW

As of December 2009, this was the largest rooftop PV system in the United States. With the busy holiday season looming, there was zero margin for error for the grid-interconnection.


  • 23 stores, 8 states
  • 2.5 MW

Blue Oak Energy is the turnkey solar installer for REI's ambitious national multi-site solar initiative. We completed the engineering, procurement, and construction for 20 stores across seven states, which were selected based on multiple feasibility studies we performed for REI. Depending on any given location, a solar-equipped store will generate between 10 and 100 percent of its own electricity. The total capacity for the 20 stores is approximately 2 MW. The first round of this work started in 2008 with a total of seven stores and 675kW installed in California. The success from this initial program continues to lead to further feasibility studies and analysis with REI on their stores across the US.

Read Case Study

Fortinet Solar Campus

  • Sunnyvale, CA
  • 908 kW

The Fortinet Solar Campus project is a 908 kW net metered distributed generation solar photovoltaic system that covers two rooftops and three parking lots to power this corporate campus. We defined the project and proposed the ideal solutions to exceed the customer's expectations. This project was engineered and constructed by Blue Oak in 2014 and we continue to operate the solar facility to meet the intended financial returns.

Read Case Study

U.S. Marine Corps Air Ground Combat

  • Twentynine Palms, CA
  • 1.5 MW

This installation was part of a larger renovation project at the complex at the U. S. Marine Corps Air Ground Combat Center (MCAGCC) and required close collaboration with all parties involved. 

Blue Oak was able to provide valuable guidance on how to adapt the arrays to complicated architecture , and our use of 3D modeling software clearly and quickly conveyed to the team various design options. 

Our expertise in rooftop PV design, coupled with our experience working with Naval Facilities Engineering Command (NAVFAC), helped keep the project's ambitious schedule on track.

Hemet Schools

  • Hemet, CA
  • 4.4MW across 17 sites
  • SCE

The Hemet Unified School District had the opportunity to reduce its electric consumption by installing solar arrays on rooftops and carports across the city's various campuses. 

The district ultimately installed solar across rooftops and carports at 17 school campuses. Blue Oak provided the DC and AC electrical design for the power purchase provider. We delivered consistent engineering documentation and quality control processes to help multiple stakeholders successfully deliver these projects. Our team also contributed by providing system commissioning inspections and as-built drawings.

First Solar Mesa Facility

  • Mesa, Arizona
  • 4 MW

The First Solar Mesa project is the largest rooftop installation in the state of Arizona with 18 acres of rooftop solar panels. The 4 MW photovoltaic (PV) system feeds power to First Solar’s Manufacturing Facility and exports excess generation to the local electric utility, Salt River Project (SRP).

Read Case Study

Commercial Rooftop Solar: A Step-by-Step Process

Your organization has decided to move forward with a rooftop solar project or series of projects. You’ve researched the commercial rooftop market and selected Blue Oak Energy as your commercial rooftop company of choice.  What happens next? 

As a leader in the commercial rooftop solar industry, Blue Oak Energy understands the importance of working methodically. That’s why we utilize a step-by-step process that accounts for every detail, from initial assessments to system maintenance. The Blue Oak Energy process begins with development stage planning, including securing engineering and construction documents. When all initial planning requirements have been satisfied, our team moves on to the building stage. The final stage is maintenance. Throughout this process, our team maintains communication, when possible, with the original roofing manufacturers and installation contractors.

Step I: Development Stage Planning

The work done during this stage serves to answer crucial questions about structural capacity, electrical infrastructure, and other rooftop requirements that will affect your project. Blue Oak engineers offer specialized site visualization and energy production modeling for clients and investors. We use our extensive commercial rooftop solar industry knowledge to assess roofing and membrane requirements, and whether your building’s roof can support a PV array. When needed, we report on interconnection options and costs. This is also the stage where Blue Oak Energy secures permits and draws up construction documents. As always, we take into account any client concerns and preferences.

Step II: Building

Blue Oak Energy is one of a handful of commercial rooftop solar companies that offers in-house engineering and construction to ensure a smooth, interconnected project. The building stage for a commercial rooftop solar project begins with an initial site evaluation, equipment selection, and ROI report. Our construction and engineering teams work together to also address any permitting issues. Working according to the approved construction documents, builders smoothly mobilize the job site, calculating any client needs, such as power outage times, into the scheduling. Blue Oak Energy job sites utilize highly skilled superintendents to ensure optimal organization, efficiency, and safety.  

Step III: Maintenance 

When deciding on a commercial rooftop solar company, you want a group that will provide support throughout the lifetime of your rooftop solar array.  That means they may need to stick with you for 25 to 30 years. At Blue Oak Energy we are adamant about the importance of proper maintenance to ensure our clients enjoy the maximum potential and estimated ROI of their rooftop solar project. Recognized by the commercial rooftop solar industry, Blue Oak’s independent commissioning and benchmarking services help ensure clients’ rooftop PV systems operate at the highest performance levels. Blue Oak Energy also offers asset management, which includes monitoring, corrective maintenance, and array cleaning.

Commercial Rooftop Solar Design

When the time has come to decide on a solar PV design, the engineering and design team at Blue Oak Energy will take into account the specific electrical and structural needs of each building. Our solar system engineers and designers are experienced with a wide range of roofing structures and situations. The type of rooftop, roofing membrane, and building structure will in large part inform the commercial solar rooftop design for the project. 

It’s All About the Roof

When designing your rooftop solar project, Blue Oak Energy will use the existing rooftop structure as a blueprint for creating the most suitable solar array design. Different rooftops call for corresponding design types.

Flat roofing systems
For flat roofing systems, which use composite or single-ply membranes, the solar developer will likely use a tilted racking system. These are not ballasted, and will require some penetration of the roof. 

Metal roofing systems
A standing seam metal rooftop requires no rooftop penetration; the solar system designer can opt instead for a clamp to attach the solar array to the roofing material. You can see an example of both the clamp system and tilted racking system in the Walgreens Distribution Center project, which uses the clamp system for the metal roofing area and a tilted racking system on the flat roofing area. 

Rock or gravel ballasted roofing  
With this type of roofing, the system engineer may need to remove some of the rocks to allow the PV material to make contact with the roof surface. There is also the possibility of water collection issues if too many rocks are left during the installation process.     

Creative Solutions

In addition to rooftop types, a building’s special characteristics may also affect commercial solar design solutions.  In one Blue Oak Energy project, the solar array that tops the San Francisco International Airport building is curved to accommodate the building’s round structure. In another unique case, the Hayward BART maintenance shop’s multi-leveled rooftop produced a shading dilemma, which led Blue Oak solar developers to create a specialized solar PV design. 

Commercial Solar System Cost 

One of reasons rooftop solar projects are so cost-effective is that they incorporate the existing building structure and electrical system into the plan. There are no new structures that need to be built. This means the focus is in generating energy, and all the benefits that a commercial solar system can produce for your company and community. 

Maintaining your Commercial Solar System

As far as continued rooftop solar maintenance, Blue Oak Energy engages the original roofing company throughout the design process, to establish continued warranty coverage. Blue Oak’s solar system engineers design the PV systems to withstand occurrences of heavy wind and rain, and expansion due to temperature changes.