About this item Warm note: This solar fan kit not have battery backup, air volume depends on solar light intensity, working good in full sun, slow in cloudy day, stop working at rainy days or night. 5.5 Inch Bigger Fan: Both of 2 fans size is 5.5×5.5×1.0 inch which is much bigger than other 4.7×4.7×1.0 inch fans. As we know some customer want bigger fan for bigger air volume. 25W Solar Panel Powered: The 25W Monocrystalline solar panels size is 15.4×13 inch which is higher efficiency transfer solar energy to power the fan. IP67 Waterproof: This solar dual fan is design for outdoor use with whole set waterproofed, including solar panel, connector, dual fan kit. Perfect Summer air circulation solution for chicken coop, greenhouse, shed. DIY Intake or Exhaust Air: This solar fan kit with dual separate fan, 15 ft Long cord for DIY ventilation purchase. Set 2 fan for exhaust, 2 fan for intake, or 1 fan exhaust and 1 fan intake air purpose.