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A Solar Rail Car

Paul Kando

8.2 meters long, 2 meters wide, seats 32, and 100% emissions-free, Billy the rail car is powered exclusively by its own solar panels and carries passengers in regular, scheduled service on a tourist line in northern Hungary, without using overhead wires.

Hungarian solar powered rail car
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Its onboard battery bank of twelve 12 Volt 240 Ampére-hour deep cycle lead acid batteries is charged by six 225 Watt mono-silicon solar photovoltaic panels mounted on the roof. Full sunshine is not essential. Since parts of the line run under a forest canopy, Billy was designed to perform even in partial sunshine.

An 11 kW (14.74 HP) asynchronous traction motor that draws its current from the batteries provides motive power. In recuperative breaking mode, the motor functions as a generator. It turns the kinetic energy of the moving vehicle into electricity, which is fed back into the battery bank. The combination of solar power and the energy recovered during breaking has proven sufficient to operate this vehicle in regular revenue service for over 3 years by now.

Driver’s seats at both ends of the car have no conventional controls. Instead, the driver plugs in a small “programmable logic controller” (PLC) -- a digital device widely used in automating electromechanical processes – and with the help of human-machine interface (HMI) programming, controls all of the vehicle’s functions using a small joy stick.

This zero emission vehicle was developed, built, tested and placed into revenue service as a cooperative project of a tourist railway and a solar company. The team used the railway’s own maintenance shop, coming in under a budget of 100 million Hungarian Forints ($360,000) -- less than a comparable rail vehicle costs on the open market.

Railcar Billy went into service in 2013. Since then it has carried more than 60,000 passengers, 32 at a time, over as many combined revenue kilometers.

Why should we care? For starters, Billy demonstrates what competent pople can accomplish when they set their mind to a project and refuse to give up. Half of Maine’s energy expenditures go for transportation – some $3 billion per year that leaves the state’s economy – mostly spent on roads, excluding the cost of our cars.

Our population is aging. Many will soon not be able to drive. What is their alternative? Our state does have neglected or under-utilized rail resources. The rest of the world is moving on. Light rail systems are found on all inhabited continents -- popular due to their lower capital and operating costs, and increased reliability compared to other systems.

Is it not high time to explore alternative transportation options? Light weight, low cost solar railcars plying Maine’s near-abandoned rails wouldn’t be the worst of them.

Billy the railcar was the brainchild of a few people working in a maintenance shop. Their goal: a zero energy railcar. Their solution lay in plain sight: a combination of proven technologies -- old (railroads, lead-acid batteries), and new (solar PV, PLC, HMI).

Who knows what may lie in our own plain sight, if only we looked?