How solar power works in Yukon in winter (hint: it doesn't really, until February)

The colder and darker it is, the more Yukoners rely on indoor heating and lighting. 

But don't bother sweeping off those grid-tied solar panels to offset the energy use — they aren't generating very much energy at this time of year. 

Between November and January in southern Yukon, when energy use is peaking and hydro reservoirs are dropping, solar panels produce just 3.3 per cent of their total annual output.

Then, during the height of summer when energy use is down and hydro reservoirs so full Yukon Energy is spilling excess water, solar panels are in peak energy production. 

But even though solar panels don't work in perfect complement with the hydrological cycle, they still play an important role in offsetting diesel in the territory, said Sean MacKinnon, senior energy advisor with the Energy Branch of the Yukon government, formerly known as the Energy Solutions Centre.

"Solar might actually end up contributing when you may not expect it," he said.

Giving back to the grid

Solar panels supply power first to the site (home or business) and return any surplus to the grid powered by Yukon Energy.

The company produces energy through three main hydro generating stations as well as with thermal (diesel and liquefied natural gas) generating stations during peak consumption.

For example, at noon on Dec. 17, 59 megawatts of power were supplied by hydro and 13 MW by thermal. Although the thermal offset from solar would have been near nil that day, MacKinnon said that will change as soon as the days get longer. 

"In mid-February, solar really picks up again," he explains. "That's climatically and historically when the skies are blue, the days are long, and there's still a lot of snow, so more reflection of the sunlight, increasing the generation greatly." 

Then, by spring, solar panels really start to shine. 

Andrew Hall, president and CEO of Yukon Energy, said solar generation is especially beneficial to the grid in April and May.

"That's very valuable for us because that's typically just before the freshet when we get our large inflow of meltwater. And so we are typically at the end of our hydro generation at that time of year," he said. 

Solar's contribution to the grid picks up again in the fall, particularly during low snow years like 2019, when hydro reservoirs were lower than usual. 

Hall said Yukon Energy is looking into seasonal storage that would allow it to capture excess energy produced by hydro and other sources, including solar and wind. He said the project would be expensive but noted Yukon has the geography required to build a pump storage system.

While Hall said there's no timeline for the project, he said it might be included in the 10-year plan the corporation is releasing in the new year. 

Solar for homeowners

MacKinnon said he is often asked if it's a good time to invest in solar panels.

"Waiting is not going to deliver you a silver bullet," is his response. 

MacKinnon said although the efficiency of solar panels is slowly increasing, the technology is not changing rapidly. With the government rebate of up to $5,000 and the reimbursement paid for energy returned to the grid, MacKinnon said the payback period for a typical home system is about eight to 12 years. 

In Whitehorse, the territory pays $0.21 per kilowatt hour for energy returned to the grid, regardless of whether the solar is offsetting hydroelectric power or diesel power. In communities reliant on diesel, like Old Crow, the reimbursement is  $0.30 per kilowatt hour. 

While the Yukon government doesn't currently measure exactly how much thermal energy is offset by solar generation in Whitehorse, the formula is far simpler in communities that rely fully on diesel. 

"In a diesel community, every single kilowatt hour generated [by solar] is offsetting fossil fuels," said MacKinnon. 

Solar as a power backup?

MacKinnon said there's interest from some people in getting a solar system as a backup during power outages.

Unfortunately, it's not that simple — or cheap. 

Utility providers power-down the grid during outages to protect workers doing repairs. That means solar users won't have access to their solar system either, unless they have a battery bank set up. 

Solvest, a solar company based in Whitehorse, said it has installed some battery backups for clients in the Yukon, but said they double the cost of the solar system. 

"We've sold more of these systems in the N.W.T, as the grid is not as reliable," the company said in an email. 

"Ultimately, battery technology has to advance to catch up with solar technology before batteries are cost effective enough to be part of most systems."