Since Toyota announced the plans of a Li-Ion battery people have been trying to figure out the actual gas milage for it. But we do know that they are planing to increase the usuage of the battery from 0-45mph to 0-60mph another way to keep the battery charged would to include a compact, efficient sun panel to help charge the Li-Ion battery, Gas would still charge but it would be a considerably less amount of gas. This would not increase the price of the car much because of mass production.

I am not sure how possible this is but still just an idea.. Post with Comments or other possibilities of a sun panel aiding to charge the battery.

Solar panels are expensive, even with mass production. There's a worldwide shortage of silicon, which is the "active ingredient" in solar panels.

If you covered the roof of the Prius with a panel of, let's say 1m x 2m, it would generate around 150 watts of power, and would cost about $700.

It would be possible to have a solar panel on the roof, but it wouldn't generate enough power to recharge the batteries fast enough while driving.

not even enough to aid the charging in the least bit, or would it just not be efficient enough? Maybe it will be more possible when they solar panel technology becomes more sophisticated

There is considerably less energy available in sunlight than many people believe. If you could convert at 100% efficiency (current solar panels are close to 15%), you'd be getting ~1.5kW/hour per square meter.

That'd be enough to give you one hour of electric power after 48-hours in the sun. For that marginal amount of improvement, you'd need to consider the impact of the additional weight.

Solar panels on houses are a different story. They can be much larger and their added weight doesn't really impact how the house operates.

Sunlight is the one of the most cheapest source of power, actually getting sun rays are free but putting things possible is quite expensive specially the solar panels
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