b'Solarthe solar panels (in direct sunlight)tocalculatebothorientationsforers are added as ballast to the (red line) was measured. During thetheproject. base of the metal stand to hold period of the day that exhibited theTheeast-westsolarpanelcon- the solar rack (typically made of highesttemperatures,weobservedfigurationalsoimprovesthewindmetal) in place. The amount of an approximately 20F (11C) cool- resistance of the solar energy systemballast needed is determined by ing/shadingeffectfromthesolarcompared with south-facing panels.project conditions and the local panels on the roof membrane. ThisThe higher back edge of the panel onbuildingcode.Ballastweight reduces the heat load on the mem- a south-facing array is more pronewill affect the roofs structural brane and somewhat shields it fromto catching greater amounts of theload-bearing capacity and could ultravioletlight,whichcouldhelpwindforce,whereasthetwohighcompress the roof insulation (if thelong-termweatheringperfor- backs of the panels in an east-westno hardboard is used), leading mance of the roof membrane direct- configuration are back to back, creat- to ponding water or eventually ly below the solar panels. Every roof- ing a smoother aerodynamic flow ofstressing the roof membrane. It ing project is different, but from ourthe wind over the panels. Simulatedshould be noted that a ballasted observationsonlow-slopedroofs,wind testing by Centroplan and Sikasystemisnotattachedtothe the solar panels are not expected toofbothconfigurationsusingtheroof or structure, so the solar add more heat load to the roof mem- sameconditionsconfirmsthatthearray could move during wind Figure 4: South-facing photovoltaic panels. Photo courtesy of Sika Sarnafil. brane below the panels. east-westconfigurationcanreduceorseismicevents.Anymove-thewindupliftontheroof/solarment of the solar array is a po-Does Solar Panelenergy system by as much as 20 pertential hazard and could dam-Orientation Impactcent to 30 per cent. age the roof membrane. Over Effectiveness? time,theconcretepaverscan Solar Racking System andalso break down as a result of Historically,themostpopularDevelopments cycles of freezing and thawing.orientationforsolararraysintheMechanically attached or se-northern hemisphere has been southSelectingtheappropriaterack- cured systems: In this type of facing (Fig. 4). However, in the pasting system to hold the solar panelssystem (Fig. 8), the solar rack few years, there has been a growingin place is critical to both the perfor- (typically made of metal) is held trendtouseeast-west-configuredmance of the solar energy system andin place by a metal fixture that solar arrays (Fig. 5). East-west con- the roof system. penetrates the roof and attaches figurations typically allow for moreSolar racking systems can gener- to the roof deck or structure. Figure 5: East-west-facing photovoltaic panels. Photo courtesy of Centroplan. panels to be installed on a roof, andally be classified as follows: The number of penetrations is comparedwithsouth-facingcon-Non-penetrating systems: In determinedbyprojectcondi-figurations, east-west configurationsthis type of system, a thermo- tions. Mechanical attachments can capture more energy from theplastic base plate or clicks madecanbeusedasadditionalse-suns rays throughout the day. of the same material as the roofcurement for ballasted racking Table 1 is a case study by the au- membraneareheat-weldedtosystems as a hybrid system; their thors that compares the use of east- secure the solar rack (typicallyuse is required by law in some west-oriented and south-facing solarmade of metal) to the thermo- areas prone to seismic activity. panels and shows that the solar cov- plasticsingle-plyroofmem- Mechanically attached racking erage or installed capacity on a roofbrane (Fig. 6). The number ofsystems pose a greater risk for can be improved by 16 per cent byclicksisdeterminedbasedonroofs because they involve pen-usingeast-west-orientedpanelsonproject conditions and the lo- etrations in the roof membrane the same-size roof. We also studiedcal building code. This type ofand have the potential for creat-the same-size projects in both Ari- rackingsystemhasbeensuc- ing thermal bridging.zona and Ohio. The installed capac- cessfullyusedbyCentroplanAll three types of racking systems ity is the same in both locations, butand Sika on more than 1,000can be used over standard low-sloped the annual solar output is greater inprojects worldwide for close to aroof systems.Figure 6: Nonpenetrating solar racking system. Arizona.Inallcases,eventhoughdecade. One manufacturer that the kWh-to-kW ratio (kWh/kW) foroffersanon-penetratingrack- Why Should the Roofing theeast-westsystemisslightlylessingsystemincludestherack- Industry Embrace compared than that for the south- ing system in their 20-year roof facing system, the east-west systemswarranty. The non-penetratingRooftopSolar?increased annual kilowatt-hour pro- systemrequiresnoballast,soItistimetoacknowledgethat duction of 10 per cent could be moreit can be used on most projectsmorewidespreaduseofrooftop financially beneficial for the buildingminimizingtheweightonthesolarisinevitable.Theexpanding Think Safe, owner and investor. The solar-panelstructure. This system does notimpact of solar-friendly policies and Work Safe, provider will most likely design andpenetrate the roof, eliminatingincentives in a growing number of installthemostfinanciallybenefi- any potential for thermal bridg- states and localities nationwide will since 1988 cial panel orientation and density. Ifing or condensation. likely lead to more use of solar en-unsure which orientation is best, it Ballasted systems: In this typeergy.TheFederalInvestmentTaxTop-Line Roofing & Sheet-Metal Inc specializesis not difficult for the PV providerof system (Fig. 7), concrete pav- Credit(ITC)orProductionTax in the installation, repair, and maintenance of industrial roofs throughout Southern Ontario. OUR SERVICES: Ohio Arizona IncreaseCommercial roofing Re-roofingRoof maintenance Skylight installation Orientation South East-West South East-WestRoof inspection,Sheet metal flashing evaluation & report fabrication & installationHistorical restoration Retro-fit curb installation Installed capacity, kW 860 1,000 860 1,000 16%Emergency roof repairs Annual production, kWh 1,023,000 1,127,000 1,550,000 1,701,000 10%(905) 602-0760 kWh/kW 1,189.5 1,127 1,802.3 1,7011325 Fewster DrMississauga, ONL4W 1A2toplineroofing.ca Table 1: Case study comparing the capacity and annual production of solar panels installed on an 80,000-ft 2roof in Ohio and Arizona in the south-facing versus east-west orientation. (Note: 1 ft 2= 0.0929 m 2 )26ONTARIO ROOFING NEWSISSUE 3 2023 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'