MELBOURNE, FLA. — IT hums, clicks, and loves the sun."A minor problem," says Douglas Cobb, driving his solar electric car on the back streets of Melbourne, "is the lack of noise. People are used to hearing something." As president of the Solar Car Corporation here, Mr. Cobb is demonstrating his solar electric Ford Festiva, a two-seater car minus all those noisy moving parts of internal combustion engine under the hood. Gone is the need for oil. An exhaust pipe is useless. In the back of the car are 620 pounds of batteries. On the hood and top are thin solar panels. Braking on the car is regenerative, which means as you apply the brakes, they help recharge the batteries. Driving range on an electric charge is an estimated 70 miles, but that's under ideal conditions. Expect around 50. On sunny days the solar panels might add another 10 miles. Price? Dig deep. The electric version is $17,500. The combination solar and electric model is $22,500. Cobb also sells as modular kit to convert a pickup truck to electric power. "Eighty percent of all driving is done in short distances," says Cobb, "and that is the niche for electric cars. At the present it costs about two cents a mile to operate an electric car and five cents a mile on gas. And an electric car is inherently safer than a car with an internal combustion engine." Cobb acknowledges that the lead batteries have to be changed around 20,000 miles and that means disposal problems for the environment. Driving on hilly terrain also shortens the driving range on a single charge. "Because some state legislatures, particularly California, are mandating alternatives to gasoline engines," says Cobb, "we're on the verge of a whole new industry."