First calculate how much electricity you will use in a day. Look at every device you use, figure out how long you will use it each day and its wattage rating.. add everything up and figure out the total electricity you will use in per day in kWH (kilowatt-hours). Then figure out how many hours of direct sunlight per day you expect to get (usually about 5), and divide by your kWH number by that, that tells you how many kW your solar panel needs to produce to replenish what you use. Then go to eBay and look up the cost of solar panels that size.. Good luck!

I've got a little offgrid rig setup in my backyard to charge my laptops, phones, etc.
I got a Brunson 26W thin film flexible module used to charge a 12V battery, I put an inexpensive charge controller ($25) between the module and battery. Then to invert the power I hooked up a xantrex pocket inverter, powers up to 175W from a 12V battery. This was about $45 at Radio Shack. You can do it relatively cheaply, $150 seems unreasonable, you will probably need a larger module than you can buy for that. Make sure you get modules that are made to output to a 12V load, this would be 20V open circuit rating roughly.
Let me know if you have more questions.

Jeffrey Yago over at Backwoods Home Magazine did a nice write-up of how to do just what your asking. It's easy . . . Have fun !!!

Add a simple solar power system to your truck camper

By Jeffrey Yago, P.E., CEM

www.backwoodshome.com/article...o93.html