When something is powered, a basic transaction occurs: energy from a given source is captured then converted to perform specific tasks.

For solar energy, this happens when sunlight is collected by panels where a semiconductor, usually silicon, converts it to electricity. Solar energy is renewable and readily available and has no toxic byproducts. Until the sun burns out on its own accord, this seems the perfect energy source. Yet, for as attractive as it is, solar power comes with a set of problems. For one, it is very expensive to install a solar-energy system that can supply all of the power to large energy users — like whole fire stations.

However, solar power is an effective way to run lower-wattage devices. Inexpensive calculators powered by small solar panels have been popular for decades. There are roll-up solar panels that can be draped over a tent to power campers' small electronic devices. And slightly larger panels have been pressed into service for more critical operations, such as lighted roadside warning signs.

The San Rafael (Calif.) Fire Department took these applications a step further. At the start of the year, firefighters Dave Holland and Steve Rutkowski had the idea to install a solar panel on the roof of an engine company rig. The intent was to wire the panel to the rig's battery to provide a charge. And the idea worked.

“The lifeline for fire apparatus and other equipment is the battery,” says San Rafael Chief Christopher Gray. “And your ability to keep the battery charged is vital.”

A common difficulty is maintaining a battery charge when the rig is away from an electricity source, Gray says. This can be especially true if a task force team is sent out for five to seven days; the units can be away from the station and not running all the time, making it hard to keep batteries charged.

Apparatus maintenance expert Mike Stankus agrees. Stankus is the lead emergency vehicle technician for King County (Wash.) Fire District 44 and FIRE CHIEF's In Service 2007 EVT of the year.

“Battery life is a huge issue on fire apparatus and ambulances because of the amount of stress placed upon them,” Stankus says. “The older emergency lighting caused large amp draws on the electrical systems and sometimes the alternator couldn't keep up with the demand. Now with the new LED lighting, there isn't as much stress put upon the charging system. But, in turn, other items such as portable radio chargers, laptops, mobile data terminals, GPS and other items have been added to emergency vehicles to stress the charging system.”

Rigs typically carry six of these batteries, which cost about $100 each and can last between three to five years depending on the level of use.

San Rafael found a thin solar panel that is 50 inches by 24 inches and mounted it in an aluminum frame, which was then mounted to the apparatus roof. The department's staff was able to complete the installation and wire the panels to the battery. In the end, the cost for materials and installation was less than $250.

The panel is made from Teflon rather than glass, and the manufacturer, United Solar, says its panels will last 20 years. Gray says the Teflon allows the panels to hold their own against water, smoke and heat.

“Of course firefighters have been known to burn up entire apparatus,” Gray says. “It is not going to survive that. But for the most part, it is going to survive the rigors that we use these rigs for on an everyday basis.”

The solar cells are interconnected but have a bypass. Gray compares this to his annual battle to find the one faulty light that renders his string of Christmas lights dark. With the bypass, he says, if one cell goes down the rest continue to function.

Gray says that one panel can deliver about 64 watts and four amps to the battery. It requires about six amps to keep the equipment running without affecting the batteries. The department has since installed a second panel on the truck.

“We figured with two panels, we could meet the needs of all the electrical components in the rig,” he says. What's more, the solar panels will complement either the alternator while the rig is running or the AC power if it is plugged in at the fire station.

Gray said he checked with American LaFrance and KME to see if this addition would affect his warranty; it didn't. Apparatus manufacturers Rosenbauer, Crimson and Smeal had not heard of using solar panels in this way.

“Solar panels on the apparatus are a great idea,” Stankus says. “I've heard about this idea, but have never seen anything until now. The location for the installation is perfect. It is out of the way and in an area that is pretty protected. If the installation is done correctly and the panels can withstand the vibration from the apparatus driving down the road, this idea should work very well.”

In the past four months the idea has worked well, so well, in fact, that Gray plans to outfit all of San Rafael's rigs and ambulances. The work already is under way and they've learned some things in the process.

One difference for the new installations will be eliminating the aluminum brackets. Instead, they will glue the solar panels to a flat piece of aluminum and attach that to the roof with screws. This will make the panels lighter, thinner and easy to remove. It also will ensure that nothing overhead, such as tree branches, is caught on them.

In rough terms, it costs a little less to install two solar panels than to replace the rig's six batteries. So how long, if at all, will it take for this investment to pay itself off? There's more to reaching that conclusion than simply calculating battery-replacement cost.

“The solar panels could pay for themselves in less than a year just through fuel savings,” Stankus says. That savings comes from being able to shut off an apparatus at the scene if the pump is not running. This also will prolong the life of the alternator, which he says can cost $1,000 — and that doesn't include installation costs.

Gray anticipates a payback period of two years based on previous battery life and costs. But the idea of saving fuel, especially in a recession, is not lost on Gray. The city's fleet administrator estimates that by shutting off diesel-powered public works vehicles when they are not in use will save thousands of gallons of fuel. Of course, the main reason for leaving these rigs running, he says, is to ensure that the batteries have enough juice to restart the trucks.

“The last thing you ever want to happen is to go out to the rig to start it and it doesn't go,” Gray says. “This is a good use of technology because it gives us an edge on reliability.” Shutting off unused vehicles also will reduce the noise at the scene.

The solar panels also will save the department money while the rigs are idle. Gray says that he was surprised to learn that the fluorescent and natural lighting in the fire station was charging the batteries when the vehicle was parked; this means less juice is being pulled from the station.

For Gray, selling the idea to the city administrators was a simple matter. Cross the Golden Gate Bridge north out of San Francisco and you'll land in Marin County, in which San Rafael is the seat. The department has 90 full-time members and six stations. It runs about 6,500 calls per year with 70% of those EMS. The department protects an area that includes 18 miles of coastline; thousands of acres of open space, wildland and interface areas; and industrial areas, high-rise buildings and residential zones. The community has about 56,000 residents and is more or less built out.

One community feature not found on a demographic breakdown is its sense of environmental responsibility. Grays says that when he approached city officials, the wisdom of the idea never was questioned.

“I just advised them of what we were doing,” Gray says. “You can see the long-term benefits. Marin County is very environmentally conscious, and so is the city of San Rafael.”

Gray says he expects to see similar solar chargers offered as an option on new apparatus at some point in the future.

N.J. Firefighters Buy Carbon Offsets

To get its community fired up about global warming and climate change, the Robbinsville (N.J.) Professional Fire Fighters Local 3786 purchased two TerraPass carbon offsets for one ambulance and one engine.

TerraPass evaluated the rigs for their carbon output (or footprint) based on the distance driven per year, weight and miles per gallon. With this information, TerraPass determined a fee relative to the carbon output. TerraPass invested this fee directly into clean, renewable energy wind farms, animal farm power, and/or carbon dioxide capturing at landfills.

By purchasing these carbon offsets, the footprint of the two pieces of equipment essentially has been removed from the roadways. The total cost of both offsets was $558. An offset for a standard passenger vehicle stands at about $60 to $100.

A University of Pennsylvania professor and his students created TerraPass.