As warehouse model department stores, big box retailers and distribution facilities grow ever more popular, their large span, flat roofs have become prime candidates for solar power panels. But it’s not that easy – flat membrane roofs are a perfect location for solar panels, but don’t offer much in terms of keeping them there. The Australia-based Powerak, however, says it has cracked the code when it comes to fixing solar structures to membrane roofs with its T-Rack Air Series — a fully engineered, total solution that takes the weight constraint conundrum out of the picture.
Powerak is is an IP Design Group that develops disruptive technologies associated with solar PV mounting system under-structurers. The group says the problem with fixing solar panels with too many large span, membrane type roofs lies in dead-load weight limits. These large span roofs often have very low load-bearing capacities, ruling out most traditional methods of retrofitting solar panels. Mechanical fixtures commonly means penetrating the roof membrane (reducing its integrity and endurance), and ballast systems add such significant weight that membrane roofs can often only handle vastly downsized solar installation, or none at all.
The Powerak T-Rack Air Series has been specifically designed to address this gap, making solar retrofitting possible for almost all these roof types, without ballast or mechanical fitting.
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The T-Rack explained
A modeled 10 meter high warehouse building with a 3° pitched roof, was studied in a non-cyclonic wind, with an approach terrain category type [light industrial-TC3]. The above diagram illustrates the wind study instrumented area [Q1], on the roof model and its infrastructure – see [Building Roof in Plan] below. The model was subjected to wind pressure to measure the max lift variation over a 360° rotation.
While others have used ultra-light racking systems to tackle the issue of heavy ballast on membrane roofs, these still need to be physically mounted, requiring roof penetration (and sacrificing roof lifespan) or making further specific equipment necessary. The T-Rack Air Series, however, is an ultra-light solar panel racking system that requires no roof penetrations, and no ballast if compliant to Powerak’s installation guidelines while accommodating most module sizes. Powerak creates an engineered mounting understructure that, on buildings up to 10 meters high and in winds of up to 85 mph, remains in place without penetration and without exceeding a roof’s total weight capacity. A perimeter fixing provides seismic integrity to the installation.
Handling wind
Central to the T-Rack Air Series is its wind tolerance. The Powerak team conducted extensive wind conditions on testing, modeling and simulation with wind engineers of MEL Consultants, Australia. These studies identified areas of peak pressure within areas of otherwise average pressure. These high-pressure zones represent concentration points for the wind’s lifting forces, and exist as peaks within spaces of relatively stable wind pressure.
The rectangular dashed line indicates the perimeter of the array positioned one half of the height of the building from the edge of the building. Deployment in this area [configuration 1], will not need fixing, and is un-ballasted. The deployment will need to be perimeter fixed with longitudinal and lateral tendons [ie: cabling], to ensure seismic stability. Deployment in the blue area if necessary will be fixed.
These peak zones are essentially worst case scenario wind spots; those areas where most lift is created in significant wind conditions. Powerak says its patented design has engineered out this lift – the adaptive combination of self-weight and the distributed strength of T-Rack Air racking array distributes the lift force from these peak zones into the adjacent regions of lesser lift pressure.
The Powerak T-Rack system allows solar panels to be installed in back-to-back-, front-to-back and front-to-front combinations. Injection molded HDPE structured foam and rolled form coated sheet metal make the system ultra-lightweight, hugely modular and allow for unlimited roof area application using a simple ‘click-fix-n-lock’ installation method. Extensive and targeted wind study analysis has validated Powerak’s signature design, making it the first of its kind to effectively and safely bridge the solar panel installation gap.
— Solar Builder magazine
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