Evergreen PV Modules PV modules produced by Evergreen Solar are distinctive in their appearance because they incorporate proprietary crystalline silicon technology known as String Ribbon. In the String Ribbon technique, two high temperature strings are pulled vertically through a shallow silicon melt, and the molten silicon spans and freezes between the strings. The process is continuous. This advantage in material efficiency means String Ribbon yields over twice as many solar cells per pound of silicon as conventional methods. Additionally, the resulting distinctive shape of the solar cell allows for a high packing density. Evergreen Spruce Modules This new higher power series of modules from Evergreen is optimized for grid-tie systems. The modules have 72 cells in series producing a higher power module. They can be used for battery charging with an MPPT charge control such as the Outback MX-60 or the BlueSky series of charge controls. Use up to 5  modules in series with the MX-60 charge control. They have Multi Contact cables. Evergreen modules are UL listed and have a 25 year power output warranty. Made in USA.