By Elisabeth Parker, Times Staff Writer Wednesday, September 22, 2010 Jon Butts rolls out a grill that uses the sun’s heat. He has spent $31,500 on the solar system that helps to run his Plant City farm. Jon Butts harvests all the energy he can from the sun. He uses it to heat his water, cool his food, power his golf carts and run an irrigation pump on his 54-acre farm in Plant City. He recently …