How a Hawaiian electric company maximized its power generation by constructing a metal solar building
The higher power demand could not be met with the current space
The Honolulu Program of Waste Energy Recovery, or H-POWER, in Kapolei, West Oahu, generates up to 90 megawatts of energy for Hawaiian Electric Company—enough to meet nearly eight percent of Oahu’s energy needs. The facility annually processes 700,000 tons of waste, which is burned to generate steam, converted to electricity and sold to Hawaiian Electric for use by the residents and businesses of Oahu.
The city has added solar photovoltaics (PV) to six existing rooftops of the City and County of Honolulu Waste-to-Energy Recovery facility operated by Covanta Honolulu Resource Recovery Venture (H-POWER). However, there was not enough space to fulfill their full commitment to solar energy production at the facility, so a new metal “solar building” was built on the adjacent lot, which would house and provide the balance sheet for the solar energy requirements.
Raising the PV panels on rooftops would reduce shading from adjacent properties and maximize power generation, and therefore was more beneficial to achieve reliable and consistent system performance.
In total, the project involved installing a 3-megawatt system — one of the largest rooftop solar projects in the state of Hawaii — that consumed 290,181 square feet of roof space for the PV system. The system would offset some of H-POWER’s internal demand of 7 megawatts to run the plant.
A steel building by Varco Pruden was chosen as the product of choice for the “solar building” structure and for the facility’s roofs. Taylor Metal Products, PBR Exposed-Fastened, Trapezoidal Rib, Metal Roofing was chosen to replace the existing roof panels for the six buildings of the H-POWER plant. S-5! Solar fixings were chosen to fix the solar panels to the metal roofs of all buildings for this project.
A building designed for the long haul
The newly constructed metal “solar building” had to be designed with long term cost effective solutions 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 of the H-POWER facility were in need of replacement.
Since the lifespan of a PV system is typically between 28 and 37 years (source: Berkeley study), the new roof and replacement roofs should meet the expected lifespan of the PV system.
The entire project had to be completed within a tight timeframe and without disrupting the operations of H-POWER, an important part of the island’s waste management infrastructure.
No roof penetration – no warranty breach
Metal was chosen for this project because it was the cheapest and best option. The construction of the “solar building” is a steel frame with a metal roof and siding, supported by a concrete slab on a level foundation. It is enclosed with overhead doors and man doors.
Metal roofing was chosen for all roofs because it provides an ideal platform for mounting PV and is the only commercial roof type with a lifespan longer than that of the PV system. A standing seam metal roof was chosen for the “solar building” because it was also easier and cheaper to mount solar PV on this metal roof type over any other type.
The S-5-S Mini clamp was chosen as the preferred mounting method to fix solar panels on the roof of the new “solar building” to allow a penetration-free fixation for the solar rack system. S-5!’s VersaGard™ was selected to attach PV racks to the newly replaced trapezoidal, visibly attached “PBR” (purlin bearing rib) metal roofs at the Covanta Honolulu plant, to meet the expected lifespan of both the roof and solar PV system.
Power generation to the extreme
The H-POWER plant and adjacent “solar building” utilized metal building components to achieve lasting performance and sustainability, while allowing the city to process and manage the island’s solid waste, convert waste into power, and further recycle and renewable efforts. could explore for a more sustainable Hawaii.
Project Name: The City and County of Honolulu Covanta H-POWER Power Plant
Place: Kapolei, West Ohau, HI
General contractor: H-POWER Solar Building, PSI & Roofer, Covanta
Solar PV Contractors: Engie & Hawaii Unified Industries
Seller: Construction of islands in the Pacific
Total project size: 3.25 MW+ solar PV on the roof
Property: Covanta Honolulu factory facility (six buildings)
Building type: Steel structure, visibly fixed, trapezoidal rib, metal roofing
roof profile: Taylor Metal Products, PBR
Roof measured: 151,876 sf (combined)
Roof height: 1:12
S-5! Product: VersaGard™ (5,700)
Number of installed panels: 3,096 (400w modules)
Property: H-POWER solar building (one building)
Building type: Varco Pruden Steel Building
roof profile: MBCI, Double-Lok
Roof measured: 138,305 sf
roof pitch: 1:12
S-5! Product: S-5-S Mini (7,200)
Number of installed panels: 5,040 (400w modules)
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