Does Solar Work When a Truck's Engine Is Running? Debunking the Myth for Fleet Managers

Many fleet managers hesitate to adopt solar technology because they believe solar panels have nowhere to send the power they generate when a truck's engine (and alternator specifically) is running. 

This misconception has prevented many fleets from using a proven technology that enhances vehicle efficiency, reduces fuel costs, and extends battery life.

The truth is that solar panels generate and supply power even when the alternator is running. 

With the proper size solar panels and appropriately designed charge controllers, the power will significantly reduce alternator load and the number of hours the generator runs in the case of a hybrid TRU.

Instead of wasting the energy generated, solar supplements the vehicle’s electrical system, helping to reduce strain on the alternator, keep batteries charged, and power critical onboard electronics.

In this post, we’ll explain why this myth persists, how solar panels work while a truck runs, and the real-world benefits fleets can see by integrating solar into their operations.

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Why This Myth Persists

The misconception that solar only works when a truck is stationary and off likely comes from traditional solar applications, such as residential and commercial buildings, where panels remain fixed in one place.

Additionally, many believe solar power has nowhere to go if the engine is running and charging the battery. 

However, commercial trucking solar solutions are specifically designed to work alongside the alternator, prioritizing solar power when available and reducing the strain on the engine-driven charging system.

By continuing to believe this myth, fleets may be missing out on a technology that can significantly reduce fuel costs, improve uptime, and extend the lifespan of essential electrical components.

Let’s break down how solar continues working while the truck is on the move and why this misconception could be costing fleets significant savings and operational efficiency.

Breaking It Down: How Solar Works While Driving

1. Maintaining Battery Charge During Long Hauls

Long-haul trucking puts immense strain on vehicle batteries.

Even with engine power, multiple auxiliary systems, such as cabin electronics and inverters, draw power throughout the journey, especially during mandated driver breaks.

Over time, battery drain will damage the battery and increase the likelihood of needing a costly jump-start or replacement.

How Solar Helps:

• Continuously replenishes battery charge during daylight hours, reducing depletion.
• Extends battery lifespan, decreasing the frequency of replacements and maintenance costs.
• Minimizes the risk of dead batteries when stopping for breaks or overnight rest periods.

See How Solar Helps Prevent Battery Drain

2. Supporting Liftgate Power Needs While Driving

Liftgates require reliable power to function efficiently, and their frequent use can strain their battery system.

Liftgate batteries can drain quickly without adequate charging and stop liftgate function during the day, leading to delays and inefficiencies.

How Solar Helps:

• Keeps liftgate batteries charged, reducing the likelihood of delivery delays.
• Reduces strain on the truck’s electrical system, extending battery life.
• Helps lower fuel consumption by reducing the need for alternator-driven charging.

Read More About Solar for Liftgates

3. Powering GPS, ELDs, and Telematics Systems on the Road

Modern commercial fleets rely on GPS tracking, electronic logging devices (ELDs), and telematics systems to ensure compliance, improve efficiency, and monitor vehicle performance.

These systems require continuous power, often relying on the truck’s battery, which can lead to unnecessary drain—even when the engine is running.

How Solar Helps:

• Solar panels provide a steady trickle charge to batteries, ensuring uninterrupted power for GPS and ELDs.
• Reduces strain on the truck’s alternator, extending its lifespan.
• Prevents power interruptions that could lead to compliance issues or tracking errors.

Learn More About Solar for Telematics

4. Powering Refrigeration Units (TRUs) During Transit

TRUs must maintain consistent temperatures throughout a haul to keep perishable goods fresh.

Running these units on engine power or battery reserves can increase fuel consumption and maintenance costs.

How Solar Helps:

• Provides supplemental power to TRUs, reducing fuel usage.
• Extends the lifespan of refrigeration batteries by preventing deep discharges.
• Lowers operating costs by decreasing dependency on diesel-powered generators.

Learn More About Solar for TRUs

The Bottom Line

Solar power is a reliable, effective solution for fleets—whether the truck is off and parked, or running its engine.

Solar panels don’t replace the alternator; they work alongside it, reducing strain, improving efficiency, and ensuring batteries and critical systems remain powered.

If your fleet isn't using this technology, you’re leaving efficiency gains and cost savings on the table.

Would you like to explore how solar can fit into your fleet’s operations?

Contact us today to learn more!

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