The Grape Solar Polycrystalline Solar Panel uses high efficiency solar cells (approx. 16.8%) and silicon material for high module conversion effectiveness and long-term output permanence and consistency. The panel should be used as a battery charger along with a Charge Controller to optimize performance and control voltage output for safe charging. The panels feature a sturdy frame with strong mechanical strength that can hold over 50 pounds/feet2 wind load and snow load.