Urban Planning: Commercial rooftops are biggest void, opportunity in solar

Standard Solar

Solar projects have so much potential when viewed as a collective bundle, like this group of 30 rooftop arrays Standard Solar is installing for the Washington, D.C., Department of General Services that combine for a total of 7 MW (pictured here).

Commercial rooftops offer a ton of potential job opportunities for solar installers and developers going forward. Analysts at the Energy Department’s National Renewable Energy Laboratory (NREL) estimate a technical potential of 1,118 GW of capacity and 1,432 TWh of annual energy generation, equivalent to 39 percent of the nation’s electricity sales.

This current estimate is significantly greater than that of a previous NREL analysis, which estimated 664 GW of installed capacity and 800 TWh of annual energy generation. Analysts attribute the new findings to increases in module power density, improved estimation of building suitability, higher estimates of the total number of buildings and improvements in PV performance simulation tools.

To calculate these estimates, NREL analysts used LiDAR data, Geographic Information System methods and PV-generation modeling to calculate the suitability of rooftops for hosting PV in 128 cities nationwide-representing approximately 23 percent of U.S. buildings-and provide PV-generation results for 47 of the cities. The analysts then extrapolated these findings to the entire continental United States. The result is more accurate estimates of technical potential at the national, state and ZIP code level.

How to use tracker control systems to your advantage

Within the 128 cities studied, the researchers found that 83 percent of small buildings have a suitable location for PV installation, but only 26 percent of those buildings’ total rooftop area is suitable for development. Because of the sheer number of this class of building across the country, however, small buildings actually provide the greatest combined technical potential. Altogether, small building rooftops could accommodate up to 731 GW of PV capacity and generate 926 TWh per year of PV energy — approximately 65 percent of the country’s total rooftop technical potential. Medium and large buildings have a total installed capacity potential of 386 GW and energy generation potential of 506 TWh per year, approximately 35 percent of the total technical potential of rooftop PV.

Key in this segment is the selection of the right mounting and racking system that makes your life easier, won’t damage the roof and is overall safe from wind and weather peril. Here’s a rundown of a few such systems and how they might save you time and cost.

System Profiles: Rooftop Ballast

Ecolibrium ballast project

Ecolibrium’s EcoFoot2+ Ballasted Flat-Roof Racking System

The EcoFoot2+ takes simplicity to a new level with integrated grounding and pre-assembled universal clamps. The modular design has just three main components: 1) A molded-resin base with no sharp edges and built-in drainage channels; 2) Pre-assembled clamps for integrated bonding without washers; 3) Corrosion-resistant wind deflectors that reduce ballast.

How does it save time and cost?

The installation speed is DNV-GL rated at 13.5 modules per installer hour. The feet can be tucked, minimizing the total footprint or allowing additional ballasting. Wire management is integrated. Bases nest to fit 50 kW per pallet, which saves on shipping.

  • Material: Black, ASA-PC, UL Listed Resin
  • Weight estimate: 3 to 7 psf
  • Slope: 0 to 7 degrees
  • Tilt angles: Landscape 10 degree; Portrait 5 degree
  • Attach option: Yes
  • Certifications: UL 2703; Class A Fire Rated; SEAOC, CFD compliant; Wind tunnel tested to 150 mph
  • Warranty: 25-year

Sollega

Sollega’s FastRack FR510

If you want the fewest parts possible, the FastRack510 (FR510) by Sollega might be the answer. It is a universal one-piece ballasted mounting system compatible with all framed modules. As with all Sollega mounting systems, the FR510 is lightweight and stackable, ships efficiently and is quick and easy to stage and install. FR510s are injection molded in California from Ultramid — an advanced glass reinforced nylon developed in partnership with BASF, the world leader in polymers. Ultramid is engineered to withstand extreme weather conditions and has a 25-year warranty. Sollega offers full engineering support services with every project, including layouts, ballast and optional anchor plans.

How does it save time and cost?

The FR510 arrives on site ready to install with no assembly required (500 kW fits in a 40-ft shipping container). All module attachments are top-down and require one size tool. Built-in reference tabs ease the alignment process. Sollega also says its system’s ability to attach rail internally provides for increased load sharing, and for hybrid systems, flexibility in mechanical anchor installation.

  • Material: BASF Ultramid glass reinforced nylon
  • Weight: 4.75 lbs
  • Slope: 0 to 7 degrees
  • Tilt angles: 5 and 10 degrees
  • Attach option: Yes
  • Certifications: UL 2703 Class A Type 1, 2 modules
  • Warranty: 25-year

Dynoraxx

Dynoraxx’s Evolution FR

The Evolution FR from Dynoraxx is designed to work with all framed modules on the market without any special ordering and requires no lead times. The system is made out of fiberglass, which provides remarkable strength-to-weight ratio that is pound for pound stronger than sheet metal, steel and aluminum and is about 70 percent the weight of aluminum on a density basis, according to Dynoraxx. Fiberglass is nonreactive with any roofing material and does not corrode or rust. Its lifespan is not affected by extreme temperature fluctuations, salty or humid air, sun, wind, acid rain and heavy snow. The use of fiberglass reinforced thermosetting resin builds structural strength directly into the Evolution. To improve part performance specific to the Evolution, the glass reinforcement is aligned along the stress points of the basket for added rigidity and support.

How does it save time and cost?

Part count is low and lightweight, which helps with shipping, and the lack of nuts or bolts means no tools are required for setup. The system comes with integrated DynoBond Grounding.

      • Material: UV-resistant fiberglass
      • Weight estimate: ~5 psf
      • Slope: 0 to 5 degree pitch
      • Tilt angles: Fixed 10-degree tilt
      • Attach option: Yes
      • Certifications: UL 2703
      • Warranty: 10-year

Kanzo

Kanzo’s K1250 Solar Racking

The Kanzo K1250 is made out of a high performance terpolymer, PC-XUV (Polycarbonate with Extreme Ultraviolet Stabilization), which has an excellent balance of UV stability and property retention. This material is designed for use in outdoor and high heat applications. It maintains an “F1” rating per UL 746C for outdoor suitability. In addition to these weatherability attributes, it has terrific impact resistance and rigidity. Kanzo says the material has a high level of chemical resistance compared to other styrenics.

How does it save time and cost?

The perfect 90 degree area allows you to measure your first row, and that’s it. The rest of the system will build out from there without measuring. The clamp provides integrated grounding and comes fully assembled, so there are no bolts or nuts or screws to worry about losing or putting together. The system is capable of 18.656-in., row-to-row spacing.

  • Material:  PC-XUV
  • Weight estimate: 3 to 7 psf
  • Slope: 0 to 7 degrees
  • Tilt angles: 12.5 degree
  • Attach option: Yes
  • Certifications: ASCE 7-10 and ASCE 7-05 Wind Tunnel Testing; ETL UL 467 Grounding and Bonding Equipment; ETL UL 2703; ANSI / ETL UL 1703 Class A Fire Rated with Type 1 modules.
  • Warranty: 15-year

 

 

— Solar Builder magazine

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