Tola, son of inventor Kong Pharith, demonstrates the solar-powered bike. The solar panel on the back charges batteries that drive the engine above the front wheel.

G etting smart with bicycles is the latest brainwave of former maths and physics professor Kong Pharith. At a cost of $200, the 46-year old inventor turned an ordinary street bike into an environment-friendly alternative to a motorbike, powered by the sun instead of high-priced gasoline.

The idea of developing his solar-powered bicycle, which he calls the SMART Bike, came to him several years ago, but he only started on the project a few months ago, working in his free time every weekend.

"I just made this bike for my child to ride to school," says Pharith, pointing towards Tola, 11, his son, who is riding the finished product. "I wanted to create something new like my SMART Bike."

Using existing technology, and scratching around to find the necessary materials, such as parts of old Japanese imported car motors, and new Chinese-made photovoltaic cells (the solar panels), Pharith has converted an ordinary street bike into a solar-powered vehicle that produces no impact on the environment, and doesn't need costly fossil fuels.

"I faced some problems at first, especially in finding solar panels," Pharith says. Solar panels are not yet widely used in Cambodia, hard to find and expensive.

The SMART Bike's design is simple. Pharith says he bought a brand new red street bike for $100, and the solar system cost him about another $100.

A plate of solar panels sit on the rear wheel's mudguard, and two old-but-still-usable 12-volt car batteries are attached to each side of the bicycle's frame.

On the handlebars, a light indicator and an off-on switch are on the left-hand and right-hand side, respectively.

"When charging, the blue light will be blinking as a signal to show the batteries are absorbing power from the sun."

Two motors are installed above the front wheel and a lever engages them with the wheel to provide traction.

"The motors are made in Japan, still in good quality, taken from old imported cars," says Pharith. "The speed of the motors is 3,000 revolutions a minute, so they can power the bike easily."

Pharith explains that during daytime the solar panel above the rear wheel can produce up to 20 volts of power. This is stored in the two batteries.

"After power is stored in the batteries, it is used to run the motors via an on/off switch," Pharith says. "It's just as simple as that, in order to reduce its complexity."

He says he could add gears, but wanted to keep it as simple as possible.

The rider gets mobile using pedal power, then has the choice of turning on the motor by a single-touch off-on switch.

"First we need to help pedaling manually, then we can turn the switch on, and our bike is moving forward," says Pharith. "It's very similar to Solex [a motor-run bicycle popular in the 1960s]."

Under solar power, the bike can run at a maximum speed of 20 km/h for around 30 minutes.

The system is on a continuous power loop, Pharith says, enabling his SMART Bike to partially recharge while in use, extending the bike's range.

"Technically, we can charge the batteries in two ways - solar power from the sun, and indoor AC socket at night," he says.

A bonus is that this can work in reverse: if there is an electricity blackout at night, power can be retrieved from the bicycle's batteries to light the house.

Pharith says committing his time, energy and money on the SMART Bike has been worthwhile: it now pays him back with recognition from others.

"I just started with my SMART Bike, and it's now a success," Pharith says. Now he's working on an application for intellectual property right protection.

The logo for his SMART Bike is being designed, and he's looking for a lawyer to help him apply for copyright. Once he's achieved that, production of bikes for sale to the public will start.

"After I obtain the protection, I can contract with any manufacturing company," he says. "They use my [solar system] technology, so I can profit with them." He says one organization has already placed an order for 100 SMART Bikes, when possible.

"What I did is just to prove that Cambodians also can do it [invent]. With sufficient opportunity and capital, we can also do what other nationals can."

Inspired by his experience and with a talent in sciences, Pharith has other renewable-power projects in mind besides his SMART Bike, but they are still at the idea stage due to lack of finance.

"Actually, my greater project is to produce a three-way-powered mini-car that can run by either solar power, electric battery or gasoline power," he says. But he estimates this SMART-car project will cost around $10,000. He cannot afford to do it alone and is looking for partners.

He takes a sheaf of documents out of his files, and shows that as well as the SMART Bike and SMART car, he's considering a solar-powered boat, and a wind-powered turbine generating electricity to power a PC in a remote commune office.

And how did Pharith arrive at the brand name SMART?

It stands for Successful Mind, Attitude and Right Thinking, says Pharith.

"It means achieving success without impacting on the environment and without reducing the opportunities for others' success."