Canadian Consulting Engineer

Photovoltaics: Feeling FIT

May 1, 2012
By John G. Smith

Florida has long been known as America’s “sunshine state,” but Ontario may be on its way to establishing itself as Canada’s “sunshine province.” The discussions simply involve a different kind of juice.

Florida has long been known as America’s “sunshine state,” but Ontario may be on its way to establishing itself as Canada’s “sunshine province.” The discussions simply involve a different kind of juice.

Since launching the Feed-in-Tariff (FIT) program in 2009, the central Canadian province has seen 188 barren rooftops transformed into solar power plants generating a combined 29 megawatts (MW) of electricity, all of which will be sold at a guaranteed rate for the next 20 years. Even though rates were recently cut by 20%, new projects will still earn a heavily subsidized 48.7 to 54.9 cents per kilowatt-hour.

“From an investor’s perspective, the Ontario model – which is built after the German model – has a lot of certainty on the financial end,” says Christian Wentzel, chief executive officer of Ontario Solar Provider, whose rooftop installations are now generating about 2 MW. Sure, the power prices have dropped, but so have equipment costs. Solar panels are 40% cheaper than they were a year ago, he says.

Anything that transforms empty space into a revenue stream can seem like a promising business opportunity, but interested building owners and their engineers still need to ensure that a rooftop can actually support a planned solar project. “This is a power plant production facility and it is serious business,” stresses Steve Horwood, business development manager for the Toronto office of Black and McDonald, which has developed a dozen rooftop solar projects.

“It’s not just this neat new green technology. You’re producing power and it has the potential to start a fire, to burn a building down, to severely injure a worker who’s working on the equipment.”

Structural engineers need to determine if the building can physically support the added weight of solar panels and racks. Electrical engineers have to consider everything from transformers to inverters when determining whether a system can tap into the local power supply. Solar developers need to optimize the system’s design, from the racks and panels to the power inverters.

The Ontario Power Authority’s Transmission Availability Tables are usually the first step in the process, determining whether local infrastructure can support the added power. “The distribution station might not have enough capacity to take another generator,” explains Sebastian Seyfarth, president of Ontario Solar Power. Without that capacity, breakers could trip and brownouts or blackouts would follow.

Available space on the rooftop will usually dictate the potential power output. Equipment that produces 500 kilowatts of electricity, for example, will tend to cover about 100,000 sq.ft. (9,290 m2). But developers need to account for more than the size of the equipment when they consider a layout. A project can involve relocating gas lines, establishing open staging areas for future maintenance work, and working around stacks and vents.

Horwood points to issues related to potential other uses for the roof. A future tenant might need to add four 20-ton HVAC systems. “They [building owners] need to know how they are reasonably going to service that asset and provide some degree of versatility in renting that space,” he adds.

The design and condition of the rooftop will determine whether the space can handle the added weight, and the results of these reviews can be surprising. Horwood has seen cases where the open web steel joists appear ready to shoulder the load, until a closer inspection shows several roof decks have been installed on top of each other. “Whatever additional capacity they had in their roof that could accommodate solar is not there now,” he says.

Even if an advanced solar system weighs as little as three pounds per square foot, engineers also need to consider any point loads. Unless the system’s supports actually penetrate the roof, a high and windy rooftop might require ballasted equipment rated at 20 pounds per square foot.

Then there’s the matter of the roof’s existing condition. A 15-year-old roof might seem perfectly sound but it may still need to be replaced before solar panels are installed. It is possible to repair a roof during the life of the solar equipment, Horwood agrees. “But if you’re leasing the roof, you need to plan for it. The [solar] developer needs to take that into account in terms of downtime on the system, which in turn is going to [have an effect] in terms of the leasing rate he’s going to pay.”

Building owners have the option of owning and operating the equipment, but most projects involve leasing space. That leaves the solar provider to invest the required capital during an approval and installation process that can last more than a year.

“You need to be really mindful of how you are managing this asset because it is a legacy project,” Horwood adds. “You have got to be thinking ahead 25 years before you stick that thing on the roof.”cce

John G. Smith owns WordSmith Media in Ajax, Ont.


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