Solar Support

Two years ago, as fallout from the recession forced the Richmond Ambulance Authority to reassess its fleet strategy, the service hit upon a novel idea to cut costs and improve efficiency: It added solar panels to its ambulances.

The RAA’s first experience with solar power had come in 2008, when it decided to trial a solar panel on a support vehicle housed in a location without auxiliary power. That vehicle had an 80-watt panel installed and wired through a charge controller directly to its battery. Results were good: “The solar charge,” found RAA’s Fleet Manager, Dan Fellows, “decreased the rate at which the battery discharged from the load of the accessory mobile communications and computers.” It also contributed to a general reduction in wear and tear. “It’s been three years,” Fellows says now, “and the vehicle has only had one battery replacement. And that was due to the headlights being left on.”

Based on the success of the support vehicle and facing a need to re-equip RAA’s fleet with a new model of chassis, Fellows began to plan a larger solution that would incorporate the panels not only to maintain battery life, but to provide powered “life support” to the vehicles’ many electrical systems. This would reduce the need for engines to run at high revolutions (high idle). The change would be eco-friendly by reducing noise, saving fuel and cutting emissions.

The re-engineering was done by Excellance in Huntsville, Ala., which remounted existing modules onto new gas-engine chassis and added the solar panels. It returned the first unit to Richmond in December 2010. The Ford 6.8L V10 chassis incorporates two 130-watt solar panels on the module roof linked directly to the main batteries through a dedicated charge controller and aftermarket engine idle system.

RAA chose the engineering configuration after considerable research of similar projects being done throughout the EMS world. Using solar panel technology is not a new idea; even in EMS a few agencies have experimented with it. Richmond’s team studied projects in Pinellas County, Fla., and Denver, among other sources, and identified that some agencies use solar systems to charge accessory batteries or reduce fuel consumption by shutting down at hospitals. That wouldn’t work for RAA. “The Richmond Ambulance Authority operates in a high-performance, system-status planned environment,” notes Chief Operating Officer Rob Lawrence. “We rarely have the opportunity to shut the vehicle off.”

RAA’s employee-led redesign group instead determined the best use of the solar technology was to charge the vehicle batteries directly, thus offsetting the additional loads from laptop chargers, mobile gateways, radios and other systems. This is where Richmond’s system differs from others researched. “We challenged ourselves to think bigger by providing a life support system to the whole vehicle, rather than targeting individual electronic components,” says Lawrence.

By a year after the first two vehicles were put into service, RAA had added six additional gasoline/solar chassis ambulances to its fleet, and the remount-and-refurbish schedule will deliver another every 10 weeks for the foreseeable future. RAA has not replaced a single battery or starter on the new vehicles.

Adds Fellows: “We see in the reports from our onboard systems that batteries on vehicles with solar are not cycled as often or as deeply as those on non-solar vehicles, thus preventing premature battery and charging system failure. All systems retain full electrical charge from the permanently topped batteries, and the vehicle’s engine management system has not had to engage the high idle. The result is lower fuel consumption.”

An added and unexpected bonus came from installing the six-foot panels directly over the patient compartment: They created a “tropical roof” effect by placing an extra layer between the sun’s radiation and the internal compartment. The helped make the A/C system more effective.

Calculating Savings

Data assessment of fuel consumption adds to the success story. Removing the need for high idle means the engine doesn’t work as hard or use as much fuel. RAA’s analysis of gasoline versus diesel ambulances revealed the true efficiency: The new ambulances deliver an average of 7.1 miles per gallon (calculated on constantly idling vehicles and miles driven) at a current operating cost of 47 cents per mile run. Diesel costs 66 cents a mile to operate (see Table 1).

While RAA is only a quarter of the way through its vehicle refit/remount program, every upgraded vehicle that arrives effectively removes $7,000 from the fuel bill a year (Table 2). The per-truck cost of the two-panel system, charge controller and a new set of batteries is around $2,200, meaning it’s easily recovered in the first year of use.

With the need to contain costs at every opportunity while consistently delivering world-class EMS to its citizens, RAA believes the new solar strategy is a wise investment. And while fuel efficiency and reduced spare-part usage represent a major economic win, crews also report that their ability to hear good chest sounds has improved significantly. RAA regards that as a clinical win as well.

Rob Lawrence is chief operating officer of the Richmond Ambulance Authority. Before coming to the USA three years ago to work with RAA, he held the same position with the English county of Suffolk as part of the East of England Ambulance Service. He is a graduate of the Royal Military Academy Sandhurst.