Solar windows, shingles and cladding? The building itself is now the solar panel
When you walk through the sun-filled atrium of the Edmonton Convention Centre or glimpse the dramatic sloped roof of the Varennes Library in suburban Montreal, it’s not obvious these buildings are generating power. After all, neither has traditional solar panels tacked on the roof.
But the semi-transparent skylights of the atrium and the shingles on the sloped roof are more than just protection from the elements — they’re building-integrated photovoltaics (BIPV). That is, they’re made of solar panels.
It’s a solution touted by Elon Musk, CEO of Tesla, which started selling solar roof tiles in the U.S. in 2017. Since then, a range of made-in-Canada options for different parts of buildings have hit the market — and installations have sprung up across the country showcasing what’s possible.
Here’s a closer look at how BIPV differs from traditional solar panels and why a lot more may be part of the buildings of the future.
What are building-integrated photovoltaics?
While traditional solar panels are attached to buildings, BIPVs are built into the exterior as key elements.
They can be anything exposed to the sun: shingles, windows, cladding, skylights, pergolas, balcony railings. One company, Toronto-based Mitrex, is even planning to use them to build greenhouses and highway noise barriers.
BIPV systems are like other solar panels in that they generate clean energy that can be used for backup power or sold to the grid. But they need to be designed differently in order to serve other functions, such as keeping out the wind and rain or letting natural light shine in.
Because of that, BIPV panels come in a much wider variety of shapes, sizes, colours and transparencies.
Why might you use BIPV instead of installing traditional solar panels?
They increase the space or area available to generate solar power.
Finding the space to install traditional solar panels can be challenging in places like cities. Meanwhile, “There is so much unused glass surface on downtown skyscrapers and building walls and windows,” said Adam Yereniuk, director of operations for Kuby Renewable Energy, the company behind the BIPV installation in the Edmonton Convention Centre, Canada’s largest, with a capacity of 169 kW.
The company also worked on a five-storey residence at Red Deer College that’s covered with solar glass cladding on three sides — 545 panels in all.
BIPVs can simplify installation and potentially save on costs.
PV Technical Services, based in St. George-Brant County, Ont., has been installing traditional solar panels for more than a decade. Co-founder Katherine Zhou said customers started asking why they had to hire one contractor to re-roof their home first and another to install the racks and panels on top — especially since the rooftop penetration required for the panel installation voided the roof warranty.
So the company developed its own solar shingle in 2016. Now, for a cost that Zhou estimates is similar to a metal roof installation, her company can put in solar shingles that both protect the roof from the elements and generate power. “That saves a lot of headaches,” she said.
They can potentially last longer than traditional building materials.
Andreas Athienitis, a researcher at Concordia University in Montreal who studies BIPV, said that while asphalt shingles typically last about 15 years, solar panels can last 30 years, with only a small decrease in efficiency. (Many solar shingle systems, such as the one from PV Technical Services, are “smart” and allow you to monitor and replace individual shingles, if necessary.)
They can potentially generate heat as well as electricity.
At the Varennes Library, outdoor air pulled into the ventilation system is preheated by the solar panels before entering the building (which also has a geothermal heating system), said Athienitis. That also cools the panels, which don’t generate as much power when they’re too hot.
A heat pump can potentially be added to increase the amount of space and water heating the panels can do, and the amount of energy per surface area that the system can provide overall.
They can replace materials with a higher carbon footprint.
Mitrex is a Toronto-based company that makes BIPV cladding and plans to make highway sound barriers. Those are two things that are often made of concrete, which has a higher carbon footprint than glass and silicon BIPV panels.
“So we are taking the carbon [out of the] system just by installing it,” said company CEO Danial Hadizadeh. Over time, he added, the renewable energy generated by the BIPV panels will offset the emissions used to manufacture them in the first place.
They have a unique look.
BIPV makes a visual statement, said Yereniuk.
“If you’ve walked through the Edmonton Convention Centre, you can see firsthand that it creates something stunning that you can’t get with any other standard glass.”
Can they produce as much power as traditional solar panels?
Their efficiency depends on the materials used and their transparency. Opaque panels can have an efficiency comparable to traditional solar panels made of the same material.
Transparent or semi-transparent panels are less efficient, since by definition a certain amount of the solar energy passes right through them without being absorbed. Hadizadeh said his company’s semi-transparent panels are about 50 to 75 per cent efficient compared to regular solar panels.
However, because BIPV panels are placed where they best serve their purpose as cladding, windows, etc., they’re not usually optimized for sun exposure, like traditional panels, and so may generate less power.
Hadizadeh hopes that as architects and developers become familiar with BIPV and understand its potential, they will start to design buildings “in a way that we maximize the power of the sun.”
Why don’t more buildings have these installed?
Yves Poissont, research manager and senior specialist in Solar Voltaic Technologies at Natural Resources Canada, estimates that, taken together, all the BIPV in the country currently has less than one megawatt of power capacity, representing less than one per cent of the distributed photovoltaic market.
There are a number of challenges with BIPV that are typical of an emerging technology:
Lack of availability. Until recently, most installations relied on products imported mainly from Onyx Solar in Spain, and they had to be customized rather than being mass produced.
However, Canadian companies like PV Technical Services and Mitrex are starting to offer access to solar shingles and cladding, respectively, that are locally developed and manufactured.
Zhou said PV Technical Services already has several Canadian installations. Mitrex expects to open a new Toronto factory in July to scale up manufacturing cladding for its first customers, which is expected to be installed by the fall. Kuby Energy, which currently sells Tesla Powerwalls in Canada, plans to sell Tesla’s Solar Roof when it’s available in Canada, which is expected later this year.
Technical and regulatory challenges. BIPV products are regulated both as building materials and electrical materials, so they have to meet two sets of requirements. Hadizadeh said that requires a lot of testing and working with the government to write regulations for a new product.
Athienitis said to encourage adoption of these technologies, building codes need to be modified and governments need to provide the right incentives.
Meanwhile, most tradespeople aren’t familiar with it, and Athienitis said there needs to be more education.
Cost. Right now, it’s quite expensive up front, although the electricity generated over its lifetime should offset that eventually, said Yereniuk. Hadizedah said his goal over the next few years is to lower the cost of Mitrex’s products to the point that they can be offered at no up-front cost to customers — instead, they would pay for the electricity generated over the panels’ lifetime (similar to the way geothermal projects are often funded in condos).
“It will definitely take off as more people realize it’s a viable technology,” said Yereniuk. “The industry is changing very fast and technology is rapidly growing and advancing, and costs are rapidly coming down.”