SCP20W12VA heavy-duty anodized aluminum frame provides strength and convenient mounting access. Cells are laminated between high transmissivity low-iron 3mm tempered glass and sheettedlar-polyester-tedlar (TPT) material by two sheets of ethylene Vinyl acetate (EVA). This protects against moisture penetrating into the module. Mono-Crystalline cells areup to 20% efficient and is said to have a service life of about 25 years.Output Power (peak): 20W Max Power Voltage (Vmp): 17.6v Max Power Current (Imp): 1.14A Open Circuit Voltage (Voc): 21.6v Short Circuit Current (ISC): 1.23A Working Temperature: -45C to +85C Tolerance: ±5% Size: 530x340x28mm Recommended Controller: 12V-5A' When using a solar panel to charge a batterya Solar Charge Controller is required and sold separately.