The sun is rising on innovations to power reefer units on Class 8 truck trailers through solar energy. Solar panels have become prevalent on reefer trailers in recent years to provide auxiliary power for “parasitic loads” like telematics and liftgates and to reduce diesel fuel consumption. But now, a Rhode Island company called eNow Inc. is bringing a solely solar-powered reefer to the market. “We have developed a system that replaces the diesel engine on a refrigerated trailer,” eNow founder Jeff Flath said in an interview.

In July, eNow announced a deal with Boston-based XL Fleet Corp. to “supply battery and power electronics systems for the first 1,000 units of eNow’s new electrified refrigerated trailer solutions,” noted a news release. Mr. Flath’s company plans to deploy 50 tests units beginning in early 2022. “And those will be to some very high visibility fleets throughout the United States,” he said.

He added that eNow is also working with Canadian carrier Day & Ross, a subsidiary of McCain Foods, on bringing the technology north of the border.

Several companies at work

XL Fleet and eNow aren’t the only companies trying to harness the sun’s rays to keep freight cool. In January, New Jersey-based PLM Trailer Leasing announced a partnership with Advanced Energy Machines to offer AEM’s net-zero solar tech transportation refrigeration units, or TRUs, on PLM’s trailer. Contacts for PLM and AEM didn’t respond to interview requests. However, according to a news release, AEM’s TRU provides 30 hours plus of continuous use between charges and can be fully charged in eight hours. A photo accompanying the news release showed a PLM trailer with about 30 solar panels on its roof. A subsequent news release in February said, “PLM has since signed agreements with major customers and began delivery of zero-emission refrigerated trailers in 2020. Interest and demand for the zero-emission technology is steadily increasing as the technology continues to prove itself as a viable alternative to diesel.”

The North American Council for Freight Efficiency has a section on its website devoted to solar panels on trailers as well as a 2018 video about solar-powered trucks. The video features the introduction of eNow’s solar-based all-electric trailer refrigeration system. “The diesel engines on refrigeration units are probably more polluting than the engines on the trucks themselves,” Mr. Flath said in the video. “So it’s one way to significantly reduce greenhouse gas emissions.”

That particular trailer, which had 14 solar panels covering the entire roof, “was to show how we could offload the energy that is normally produced from the alternator, and save fuel mileage on the complete truck,” Mr. Flath told Canadian Sailings. Since then, the company has developed a system that replaces the diesel engine on a reefer.

Dave Schaller, NACFE industry engagement director, was also featured in that video. He admitted in an interview that he’s isn’t familiar with the latest developments in solar panels powering reefers. However, he did say that small solar panels on top of trucks are becoming more popular for such functions as keeping the GPS system alive. “Since there are typically three trailers for every tractor, doing a large-scale solar isn’t economically viable in a lot of cases,” Mr. Schaller said. “But there are certain aspects of the industry, for instance expedited freighters if they’re running refrigerated bodies. So there’s a lot of room there to put solar panels on an expedited box and be able to run cool freight.”

Mr. Schaller added that if solar panels can provide enough power to a battery system so that the diesel engine doesn’t have to turn on at night, “you’ve accomplished something right there.”

Some 75,000 solar panels

NACFE lists several manufacturers on its webpage about solar panels. They include Go Power!, which is headquartered in Victoria, B.C. and has been owned since 2017 by Valterra Products of Mission Hills, Calif.

“Our solar-powered reefer solutions can eliminate dead batteries — even after long periods of inactivity,” says a posting on the Go Power! website. “Or, you can power the trailer entirely with a large custom solar array.”

Go Power! declined an interview request but referred the inquiry to Paul Kroes, market and technology insights leader for Thermo King-Trane Technologies.

Mr. Kroes said Thermo King has been putting solar panels, including those made by Go Power!, on trucks and trailers since 2014 and now has about 75,000 panels in the field. “We’re talking anywhere from 30 or 25 watts up to multi 100-watt setups, all designed to support more parasitic loads, like telematics, or to support liftgate operations and stuff like that,” Mr. Kroes said. In most cases, that’s one or two solar panels on a trailer. Reefer trailers with large arrays are currently rare, he said.

All those panels have provided Thermo King with a wealth of data about the performance and longevity of solar panels. “That gives us pretty good insight into what panels can do and, more importantly, their level of reliability,” Mr. Kroes said. A problem is that clouds, rain and snow can reduce the performance. “When you need to power a full reefer and need to depend on that, reliability is a major factor, especially in northern climates, where during six months out of the year you get very little sun,” Mr. Kroes said. Ambient outdoor temperatures, meanwhile, in places like Arizona and New Mexico in the summer “get so high that they offset the benefit of solar,” Mr. Kroes said.

Most solar-powered reefers in North America are in southern California, where it’s sunny almost every day and the temperatures aren’t too hot or cold, making operational efficiency more predictable.

Collecting more data

Mr. Flath’s eNow is looking to gather data of its own to demonstrate that solar power can replace diesel on a 53-foot reefer, for short-haul reefer trucking at least. The company has operated three units for a few years and moved the technology from low to high voltage. “We think it’s ready for prime time now,” Mr. Flath said. “But having only three units in a huge market just isn’t enough data. We believe by putting these additional 50 units out, that not only will the test data be shown in real time, but it gives us the ability to acclimate the system to everybody’s different use. Because everybody uses different hours a day; everybody uses different temperature ratings.”

The company calls its system Rayfrigeration, a play on the word “refrigeration.” It involves putting 14 panels capable of generating 6,000 watts on a 53-foot trailer also equipped with a 107-kilowatt battery pack. Shorter trailers would have smaller arrays. “The battery pack is charged from the solar array, as well as utility power when the trailer gets plugged in when it returns to its home base at night,” Mr. Flath said. “And then the energy out of the battery pack is what’s providing energy to the refrigeration unit on a daily basis between eight and 12 hours of run time.”

Rayfrigeration is meant for short-haul hub-and-spoke transport in which trailers leave a distribution centre in the morning, drop off goods at stores, and return to the distribution centre at night “versus over the road where you may be taking a load from California to Rhode Island,” Mr. Flath said.

On that 2018 NACFE video, Chris Trajkovski, Vice-President of transportation and fleet maintenance for C&S Wholesale Groceries, described how such a system work: “The idea is that we would make several deliveries and perhaps pick ups and back hauls back into the distribution centre over an 11-hour period. When the trailer is at the dock either loading or unloading, then we’ll use utility power to charge the batteries. When the trailers are in motion during the day making deliveries, the solar array will get us through that 11-hour work cycle.”

High-capacity battery development

According to that July news release, eNow has already deployed more than 4,500 solar-based systems to help maintain auxiliary batteries for such applications as telematics, liftgates and in-cab HVAC. For its part, XL Fleet is “developing the high-capacity integrated lithium-ion battery and power electronics technology that will be installed underfloor on the Class 8 trailer, providing approximately 12 hours or more of run time between charges,” the news release said.

Under the deal, XL Fleet will invest $3 million in convertible notes in eNow and earns the right to acquire eNow at a pre-determined valuation. Mr. Flath said a difference between Rayfrigeration and AEM’s system is that AEM designs and uses its own refrigeration units. “We power existing refrigeration units that have been in the market for 50-plus years,” Mr. Flath said. “So a customer doesn’t have to gamble on a totally new refrigeration technology at the same time as he’s reducing his fuel consumption.”

To start, eNow will do newbuilds but there is potential for retrofits in the future. The cost of a Rayfrigeration system, which is leased, is about double the $80,000 cost of a conventional reefer system. With incentives and operating savings, however, Mr. Flath estimates the total cost of ownership over 10 years will be about 30 per cent less for eNow’s system. He sees a huge potential market, considering that North America has about 500,000 reefer trailers and adds around 50,000 each year. “We think it’s a billion-dollar-a-year market, not only on the mobile and the moving platform,” he said in that 2018 video. “But just think about fleets that have trucks and trailers parked in the distribution centres. We can send that energy back to the facility as well.”

Some solar skepticism

Thermo King’s Mr. Kroes isn’t so bullish. “We see solar as probably playing a minimal role in future electric refrigeration unit and power,” Mr. Kroes said. “It comes down to a matter of battery technology and other what we call range-extension technologies like regenerative axles. Those are maturing at a much faster rate than solar.” It makes better economic sense to put that money toward solar panels on the roof of a distribution centre, so they can be used to generate power all day, rather than to use those panels for part-time duty to charge batteries on reefers. Solar on the roof of a trailer can act as “an opportunity power source,” Mr. Kroes noted. “So when the sun is out, you can charge the batteries, and you can return to base with probably a reduced need to recharge,” he said. “But my concern there is that you have to have duplicate infrastructures on the trailer.”

It’s not as though Mr. Kroes and Thermo King are down on solar. “Well over half of our equipment that goes out the door gets a solar panel,” he said. And while he admitted that he talks solar down quite a bit, the company is still evaluating solar power’s potential. “Our approach is that if a customer wants solar, we need to design our systems to be able to accommodate that power demand. But second, we want to be able to understand the operating conditions so we can help our customers predict their range,” Mr. Kroes said.

Mr. Flath also agreed that solar has its limits: “At this point in time, we can feed excess energy from the trailer back to the truck. But I don’t think solar on the trailer is ever going to provide enough energy to run the truck itself.”