RV service technician said cell was not functional. Would like to install a solar cell large enough to keep batteries charged and possible running lights and refrigerator, if there is room on top. Located manufacturer of current solar cell and they have a 40 W. Have not order or purchased one yet. Travel Supreme is 42 DSO4 - 43 ft. I will be at RV later this week and will get measurements for size I can install. Do not like hooking up one until I locate what it is powering. Appreciate your help and advice. Great advice from both. Thanks. Merry Christmas.