You know those 12v picnic cool boxes that lower the internal temp to 10-20 degrees below ambient temp? Could I build a big version in the roof(?) of my van? If it was rigged to a solar panel it would cool your car all day while it was sunny without guzzling your fuel.
You are talking about engineering, and that takes a lot of knowledge about a lot of subjects. Do you know how much voltage a Peltier junction needs? How many amps to get a 20 degree effect? How much insolation it takes for a silicon cell to produce that much power? How much dust a cell of that size might collect? Do you even know what those words mean?
Here is a free course in basic electronics. It will take you a while to learn what you need to know. www.phy.davidson.edu/instrumentation/NEETS.htm