The Honolulu Program of Waste Energy Recovery, or H-POWER, in Kapolei, West Oahu, HI, generates up to 90 megawatts of energy for Hawaiian Electric Company. That's enough to meet nearly eight percent of Oahu’s energy needs. The facility processes 700,000 tons of waste annually, which is combusted to generate steam, converted into electricity and sold to Hawaiian Electric for use by Oahu’s residents and businesses.

The city recently added solar photovoltaics (PV) to the rooftops of six existing buildings at the City and County of Honolulu’s Waste-to-Energy Recovery facility, operated by Covanta Honolulu Resource Recovery Venture (H-POWER). However,since the existing roof surfaces didn't provide sufficient space to meet the solar energy production commitment for the facility, a new metal “solar building” was constructed on the adjacent lot, fulfilling the balance of the solar power requirements.

PV panels can be installed at ground level, but placing the panels on the buildings roofs reduced shadowing from adjacent properties and maximized power generation, and was therefore more favorable to achieve reliable and consistent system performance.

In total, the project involved installing a 3-megawatt system, making it one of the largest rooftop solar projects in the state. It consumes 290,181-square feet of rooftop space and offsets some of H-POWER’s in-house demand of 7 megawatts of electricity to run the plant.

A Varco Pruden steel building was used for the construction of the new "solar building” structure, including its rooftops. Meanwhile, Taylor Metal Products' PBR Exposed-Fastening, Trapezoidal Rib metal roofing panels were chosen to replace the old roofing on the six existing buildings. Solar attachment products from S-5! were utilized to secure the solar panels to the metal rooftops of all buildings for this project.

The Challenge

The newly constructed metal “solar building” had to be designed with cost-effective solutions for the long-term, both for the PV project and for various recycling programs within the building. In addition, the 30+-year-old metal roofs on the six buildings at H-POWER facility were in need of replacement. Since the service life of a PV system is typically between 28 and 37 years, according to a Berkeley study, the new roof and the replacement roofs would need to meet the expected service life of the PV system. 

The entire project also had to be completed within a tight time frame and without disruption to H-POWER’s operations, which is a key component of the island’s waste management infrastructure.

The Solution

Metal was selected for this project because it was the lowest cost and best use option. The “solar building” structure is steel framed and features metal roofing and siding. It was erected atop a concrete slab on a grade foundation. It is enclosed with overhead doorways and man doors.

Metal roofing was chosen for all the roofs as it provides an ideal platform for mounting PV and is the only commercial roof type that features a service life that exceeds that of the solar PV system. A standing seam metal roof was chosen for the “solar building” since it was also easier and less expensive to mount solar PV to this metal roof type over any other.

The S-5-S Mini clamp was selected as the preferred attachment method to secure solar modules to the roof of the new “solar building” to allow a penetration-free attachment for the solar racking system. S-5!’s VersaGard™ was selected to secure PV racking to the newly replaced trapezoidal exposed-fastened “PBR” (purlin bearing rib) metal roofs to meet the service life expectations for both the roof and the solar PV system.

Long-Term Outlook

The H-POWER plant and adjacent “solar building” utilized metal building components to achieve lasting performance and durability, while allowing the City to process and manage the island’s solid waste, converting trash to power, and to further explore recycling and renewable efforts for a more sustainable Hawaii.

The Contractor's Take-Away

“The S-5! VersaGard™ roof mount works extremely well with traditional PV racking systems and simply saves installation time. VersaGard eliminates the additional L-Foot component, and the slotted channel allows for as much adjustibility as you’d possibly need with a traditional L-Foot assembly. Every project requires a unique application, and I believe S-5! offers a vast array of products for just about any metal roofing situation, for a simple and easy solution.”― Dan Johnson, Project Manager, Hawaii Unified

Project Credits/Stats

Project Name: The City & County of Honolulu Covanta H-POWER Plant
Location: Kapolei, West Ohau, HI

Architect: HDR
General Contractor: H-POWER Solar Building, PSI & Roofing Contractor, Covanta
Solar PV Contractors: Engie & Hawaii Unified Industries
Vendor: Pacific Islands Construction

Total Project Size: 3.25 MW+ of rooftop solar PV

Existing Buildings

Total Number: six
Structures/New Roofing: Steel Structures with new, exposed-fastening, trapezoidal rib metal roofing
Roof Area: 151,876 sf (combined)
Roof Pitches: 1:12
Solar Panel Attachment Hardware: S-5! VersaGard™ (5,700)
Number of Solar Panels Installed: 3,096 (400w Modules)

New Building

Total Number: 1
Metal Building Manufacturer: Varco Pruden
Metal Roofing Manufacturer/Type: MBCI Double-Lok Standing Seam
Roof Area: 138,305 sf
Roof pitch: 1:12
Solar Panel Attachment Hardware: S-5! S-5-S Mini (7,200)
Number of panels installed: 5,040 (400w Modules)