One of the major projects for the trip to Guatemala was to built two soda can solar collectors to show the coffee producers an environmentally friendly way to dry their coffee beans and other fruits and vegetables. Rufino had purchased the building materials and I brought down the needed tools and the fan and fan temperature controls. It is difficult to check a 4x8 sheet of plywood on to an airplane especially now, what with the baggage fees. I also brought down some high temperature silicone caulk and can openers. One of the first problems we had was the can openers that worked so well at cutting off the tops of soda cans in the USA did not work on the same Coke cans in Guatemala. I don't really know what the difference was or why but it was enough that the can openers did not work. That problem did slow down the project. We used tin snips and the old fashion Swiss Army knife type of can openers. Once we got the tops off the cans we drilled the three holes in the bottom of the soda cans.
The cooler air enters the bottom of the collector and as the air is heated by the sun it will rise and empty out the top. We added a fan and a temperature control to aid the coffee bean drying process.