Solar Power Moves From Roofs to Semi-Trucks and Trailers

Solar power technology is moving from the roofs of homes to the tops of semi-truck and trailer combinations.

The North American Council for Freight Efficiency believes solar panels mounted on tractors trailers can generate enough electricity to help power heating and air conditioning systems, liftgate operation, refrigeration and telematics systems.

The technology is less useful for generating fuel savings, according to Mike Roeth, executive director of the North American Council for Freight Efficiency. The council presented its findings on solar panels and trucks in a webinar Wednesday.

Fuel efficiency is an important issue for the trucking industry. With the average Class 8 truck getting just 6.4 mpg and traveling about 100,000 miles per year, any improvement in fuel efficiency could potentially save thousands of dollars each year.

Solar only saved about $200 per year, according to the NACFE report, which drew its conclusions, in part, from research and interviews with fleets that use solar.

Adding solar panels to trucks and trailers has become more feasible as the cost of technology has declined.

“The usual reaction is, ‘What do you mean?’ There’s not enough space,” for the panels, Roeth said.

But the technology is starting to roll out.

In one test, a solar-powered cooling system developed by eNow, a Warwick, R.I., builder of solar panels could cut harmful diesel emissions on a refrigerated truck trailer by almost 100 percent. It builds power systems for big-rig air conditioning, lift gates for straight and semi-truck trailers, safety lighting for emergency vehicles and telematics systems that require an energy source to ensure batteries are always charged.

Using the sun to top off or maintain the charge on a truck’s battery HVAC system means the truck doesn’t have to run the engine or plug in because its battery life is extended through solar charging.

With drivers incorporating more appliances, such as televisions, refrigerators and coffee makers, into their cabs, solar can also augment the battery life supporting these sorts of hotel loads for longer periods of time.

But the “slam-dunk” applications for solar, Roeth said, are maintaining the batteries on liftgates, refrigerated trailer diesel power units and trailer telematics systems that relay GPS, temperature and other data to the fleet.

“The battery savings and the benefits to the drivers generally make solar something fleets should be considering,” Roeth said.

Unlike the thick, hard solar panels used on most buildings, solar panels on trucks are thin and flexible to better fit their curved surfaces. But they also add cost, and the rate of return on investment varies.

Some are skeptical of the technology’s application for trucking.

Solar in trucking “is used very little right now,” said Antti Lindstrom, an analyst with IHS Markit. “I don’t really see much growth there, because trucks operate in so many different environments and many are not that constantly exposed to sunlight.”

Trucks don’t operate solely in sunny climates. The amount of sun they’re exposed to varies by time of day, geography and weather conditions, and that radically affects the amount of energy they’re able to generate.

The NACFE report calculated one payback scenario — for a solar panel installation on top of a tractor to support a battery HVAC system. The cost and installation were $2,500 and the payback was about three years.

The question is whether fleet operators think the savings justify the cost, said Michael Ramsey, a transportation analyst for Gartner Inc.

“If solar costs $5,000 and takes five years for the payback, very few people will do it,” Ramsey said. “The trucking industry is more return-on-investment focused than you or I when we buy our cars.”

The average truck has a 10-year life span and travels about 1.3 million miles, but many fleet operators sell their trucks after four or five years of operation, before they may be able to recoup their upfront costs in long-term savings.

Fleet managers could also be concerned about the potential for down time and maintenance, Ramsey said. “You take a truck out of the fleet because the solar panels stop working, and that eliminates very quickly any value you got for that system.”

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