Converting CNG Vehicles Into CNG Plus Solar Powered Car (Hybrid Car)

First you have to start out with a CNG IC/Electric hybrid, or convert your present CNG vehicle to some variation of that scheme: You need batteries to store the solar power, and an electric motor in the drive-train to use the stored energy. The related hybrid features of smaller IC engine, regenerative braking etc are also very helpful because the contribution from vehicle mounted solar panels will be so small. You could augment this by a stationary solar array that plugged into the vehicle, but then you need extra battery capacity which is added weight and expense.

Overall, adding solar to a regular car, that just happens to be CNG powered is a losing proposition all the way around. At least with a hybrid, you could use solar power to keep the batteries topped off, but as far as any meaningful contribution when driving, there will be none with a "normal" car: you would need a very streamlined, ultra light weight vehicle for any conceivable good result, and that runs the risk of becoming a hood ornament on some semi rig. Even if your car mounted solar panels delivered 300 Watts, after conversion and other losses you would be very lucky to see a 1/4 HP contribution. By the time you added in the effect of the extra weight, you end up a loser, and thats assuming your installation didn't increase wind resistance. If did, then your losses have multiplied.

But for a school project: Why not? (Provided you don't have to pay for it and drive it.)

On the other hand, you might install some dummy solar panels, conceal your exhaust pipe, add big "SOLAR POWERED" decals to the sides of the CNG car and soak up all the envious looks you get as you tool down the highway.

I would more or less agree with the comments of Greg G.

The solar panels provide about 120watts per square meter of surface area and you dont have much of it on a car. Therefore the bottom line is that with that small power available (and that too on sunny days only) what real objectives are to be gained?

I suppose you could use a large stationary solar cell array (10 M²) cabled to the car as required to charge the LI batteries in the car. Then you'd use an enlarged version of the car's alternator to charge the batteries while driving -- in other words, you'd have the equivalent of a plug-in hybrid, but instead of plugging into the grid you'd be plugging into your solar array. The major hitch in this is you'd want to charge your car at night, usually. But you could have a set of stationary batteries which would be used to charge those in the car. You could also swap out a battery packs, I suppose.

There are number of battery charger ICs and circuits for such kind of application. www.ti.com and www.maxim-ic.com and perhaps few more may be manufacturing such items. Lithium not going to be cheap but I am sure these lads in south will spend their worth in making such cars and may like to display all the way in USA. I will always underestimate them by their English. Boys can spend few thousands of dollars if that can give results. They may be living only on cup of tea and bread but very keen in learning.

Lithium battery charging requires current pulsing and temperature monitoring. Simple charger may be only with diode and a series resistor, but that may kill the battery life very badly. Batteries if over charged or excessively heated then it may also explode.

Petrol to CNG conversion is not new thing for them and there are electrical vehicles around. Solar powered vehicle is sure new to them even though it is not so in other parts of the world.