There seems to be a lot of interest in solar panels lately. Back in 2018, NACFE thought there was enough interest to warrant a deep dive into the topic and the result is our trust report, Solar For Trucks and Trailers. The additional power obtained from the solar panel(s) can supplement that from the engine’s alternator, maintaining the batteries at a higher average state of charge, which extends battery life.

See also: The latest NACFE report found all medium-duty box trucks to be electrified

The conclusions from that report are still valid.

  1. Solar technology for trucks has advanced to the point where the panels on the market are flexible, thin, easy to install, and reliable. Other applications, such as supporting batteries for trailer telematics systems, are an excellent application of the technology and should be strongly considered for future purchases. For other applications of solar technology, the cost versus benefits must be evaluated to determine if it makes sense in the specific application.

  2. Fuel savings are usually a very small part of the overall benefits that come from installing solar panels.

  3. Solar panel installations must be properly sized for their intended application.

  4. There is limited evidence at this point from fleets that the payback from investing in solar panels equals that claimed by solar panel suppliers. The benefits fall into several categories, with the biggest benefits being extending battery life and avoiding emergency roadside assistance for dead batteries.

One thing that I think would help accelerate the adoption of solar panels is if they are integrated into trucks and trailers instead of add-on items. This is done by solar panels on refrigeration units. Those panels are small—27 watts—and are there to help maintain the charge in the reefer engine starting battery and maintain the batteries in the telematics system.

The solar panel that mounts on top of a trailer is a 50-watt unit and that’s too small to provide anything but a trickle charge for the batteries. However, solar is still a great technology for trucks but we need to be careful that we don’t translate it into providing more power for vehicle propulsion or more cargo cooling. And don’t forget, with today’s lead acid batteries maintaining the battery’s charge level when the vehicle is stationary can greatly help battery life.

As we move to a battery-electric future, I hope to see more interest in solar panels as a way to expand the range of batteries powering the car. I expect to see more work done to make solar panels more valuable on the truck as more fleets are expressing interest in them as a way to extend battery life and harness free energy from the sun .


Michael Roeth has worked in the commercial vehicle industry for nearly 30 years, most recently as executive director of the North American Council for Freight Efficiency (NACFE). He served on the second National Academy of Sciences Committee on Technologies and Approaches for Reducing the Fuel Consumption of Medium and Heavy-Duty Vehicles and held various positions in engineering, quality, sales, and plant management with Navistar and Behr/ Cummins.

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