high efficiency cheaper price 5 year gurantee ,25 years of 80% power. 1:Every monocrystalline solar panels'power is 310w,allowable deviation±3%,average power 310w.2:156*156 solar cells,voltage is 36.1v,circuit current is 8.58 A,no bubble.3:the quality standards:TUV standards. 310w monocrystalline solar panel