Echodale Park, Medicine Hat, Canada, in Autumn

By Brent Harris

Maintaining a Unique Independence

Located 250 km east of the city of Calgary, Medicine Hat, Alberta, Canada, home to just over 60,000 residents, is rich in natural resources and pristine wilderness. Built on top of 3,000 natural gas wells, the city of Medicine Hat is one of the only cities in the world to own and manage its own electric and gas utility.

Understanding that their kitty of natural gas will eventually run out and wanting to maintain their municipal independence, Medicine Hat began to look for other sources of energy to power their city. According to Environment Canada, the southern Alberta city receives approximately 2,500 hours of sunshine per year, making sunlight Medicine Hat’s second biggest energy reserve. Marry that with the city council’s understanding that they need to shift away from fossil fuel dependency made solar a natural fit.

The city’s “Community Environmental Roadmap” was recently inducted in 2006, with a goal to reduce natural gas and conventional electricity consumption 20% by 2020. This complimented the city’s desire to maintain energy independence and helped create the Medicine Hat “Nature’s Best Reserve Fund” This fund is dedicated to investment in renewable energy projects and will cover 50% of the project costs up to CA$50,000 per person or building; they are pushing for solar PV and solar thermal with city residents.

“From our City Council’s point of view, we could certainly look the other way and keep on selling more gas or electricity to the profit of the Energy Division,” says Medicine Hat Mayor Normand Boucher. “But, we have taken an ethical and moral approach to inform, educate and invest in Medicine Hat citizens and companies. By reducing the environmental foot print we can still move ahead and grow.”

The Installation

The owners of the Ridge Professional building decided to go big with their PV system using 180 Day4, 48MC modules and nine SUNERGY ELV 208 solar inverters. This system will produce 40 megawatt hours per year approximately half of the building’s electrical needs each year.

Wanting to support local solar companies, the selection of Day4 Energy solar modules, Sustainable Energy Technologies inverters, and Goose Creek Renewables to build their 30 kW rooftop PV system was a natural fit. The Ridge Professional building has added many benefits. First is safety. Using a low-voltage inverter allows the Medicine Hat installation to operate below 120 V DC; minimizing the risk to emergency personal and maintenance workers who may come in contact with the array.

In addition this inverter is capable of being roof mounted anywhere in the world: rated for operation in temperatures ranging from minus 40。C to plus 50。C. Unlike traditional inverters which are mounted indoors (requiring the owner to run live DC voltage through their building which can measure up to 600 V), a roof-mounted inverter removes this risk, increasing the overall safety of the system.

Second is energy efficiency. Roof-mounted, low voltage inverters mean high system availability throughout the year. By using a parallel system layout the elimination of module mismatch can generate a power yield improvement of three to 5% over a similar high voltage product. In a rooftop application, where incidental shading is often unavoidable and where an ideal orientation is not always an option, energy yields can be improved by as much as 15%.

Third is ease of maintenance. The Ridge chose to use an inverter which has a unique modular design wherein the inverter can actually be separated from the transformer. This modular approach improves the ease of installation by breaking up the weight of the inverter into two pieces and decreases the reliance on manufacturer personnel for repairs by making it easy for a single person to swap out the inverter module in case of a problem. As well, with Sustainable Energy’s user friendly software applications anyone can be trained to monitor and record system data.

“We could not have asked for a smoother installation process. Sustainable Energy’s inverter technology naturally complied with Medicine Hat’s interconnection rules and we were able to address the City’s safety concerns without sacrificing cost or performance,” said Rick Dunsmore, President of Goose Creek Renewable Energy, who designed and installed the system. “Safety is absolutely the highest priority for all of our installations, both during the installation process and for the life of the system. Manufacturers need to incorporate these types of solutions into their product design to ensure a safe, high quality installation every time and Sustainable Energy has done this.” Although the installation went smoothly, things were not so easy when it came to system layout. Challenges arose when it came to creating a system which would be aesthetically pleasing to all building residents, and which could also work around the shading imposed by existing structures on the roof.

Commercial rooftop systems are subject to a variety of constraints that are not often appreciated by equipment suppliers or solar system designers. It is very rare that a commercial rooftop system is actually installed with ideal tilt and orientation, or without experiencing some degree of shading. Structural considerations tend to dominate; equipment and system integration techniques used must be tolerant to this.

With low-voltage, rooftop mountable inverter technology external constraints are easily managed. With conventional inverters solar modules are wired in long strings in series. This makes them susceptible to any adverse conditions such as partial shading causing them to lose a disproportional amount of power in any non-ideal situation. Using a low voltage inverter to connect modules in parallel effectively eliminates module mismatch so that if one part of the system is partially shaded for a portion of the day it does not affect the operating efficiencies of the rest of the system. This allows system operators to generate more kWh then they would with a series array, which also generates more revenue.

Environmental Impact

The three professionals who invested in the system at the Ridge, and many of the people of Medicine Hat are very pleased to see such progress on the renewable energy front in Medicine Hat. Many residents feel that the solar system installed on The Ridge is among the first of many installations projected for the city of Medicine Hat.

“Exposure and leadership of The Ridge installation has inspired others to walk down the same road,” said Russell Smith, Manager of Energy Sustainability in Medicine Hat, “Incredibly our solar PV and solar thermal grant programs are 50% subscribed in just the first year. Interest is definitely growing.” In the wake of the global recession many citizens are scrutinizing their investments more, and recognize the fragility of conventional energy sources. They desire to save money, become more self sufficient and invest in items which will provide sustained financial benefits. For the forward-looking professionals of “The Ridge” not only is their new solar system contributing to large environmental savings, and preventative health measures?it’s also helping their bottom line. Each year this 30 kW system will save approximately CA$3,000/year in electricity costs.

With such a large system the benefits are innumerable. The Ridge Professional building is now reducing their environmental impact in a significant way. This 40 MWh/y system will offset approximately 27 metric tones of carbon dioxide emissions; the equivalent of planting 1,080 maple trees, and the carbon dioxide they would sequester over a 25 year life span. If the entire million dollars of commercial incentives was spent on solar PV it would result in 200 kW of installed capacity for Medicine Hat. would result in an annual electric generation of 280 MWh of power, displacing approximately 2,250 gigajoules of natural gas and adding to immeasurable educational and national leadership gains.

Paving the Way for a New Canadian Industry

The Ridge Professional building is a large step forward for renewable energies across Canada and Medicine Hat, but it is just the beginning. Parallel to their commercial and residential grant program, the city is examining putting in place a 1 MW solar thermal installation to provide supplemental steam to the turbines at its existing combined cycle gas plant; a nine-million dollar project; but for now will be focusing on their residential and rooftop projects. The accomplishments made in Medicine Hat for decentralized renewable energy, and those projects set to begin are a true testament to what can happen when residents, municipalities and utilities all work together toward a common goal.

Through such incentive programs, like the one in Medicine Hat and provincial programs like Ontario’s new Feed-in Tariff (FiT) program, the solar industry in Canada is perched to take off.  Historically residential solar power systems and utility scale solar plants have dominated the solar power discussion, but the commercial rooftop solar market has the biggest long-term potential both in terms of installed capacity and contribution to our energy supply. The combination of installation economies of scale and the higher value of electricity generated at the point of use will drive this segment of the market to the front over the coming years. The winning technologies will be those that excel in structurally optimized installations, ultimately leading to true building integrated installations.

Brent Harris is VP of Product Development at Sustainable Energy Technology (http://www.sustainableenergy.com/).

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