The 5W panel kit does not require a charge controller if the battery to be used is larger than 35Ah **Cell performance warranty states that at 20 years the cell output will be no less than 80% of new performance values – i.e the cell degradation rate will be no greater than 20% in 20 years. RS 5wp panel Bulk Pack. The 5wp panel is ideal to prevent battery drain in caravans, motor homes and boats. It contains a reverse feed diode to prevent back feed and is supplied with all the necessary cable, connections and detailed instructions. The ideal choice to prevent battery drain. The 5 watt panel provides a continuous trickle feed maintaining and extending the life of any 12 volt battery. The 5 watt solar panel is fitted with a blocking diode to prevent reverse current drain. High efficiency crystalline cell for all weather charging Perfect for battery maintenance and off grid lighting projects Water resistant, robust construction for outdoor use. In built diode protects against battery discharge 20 year cell warranty and 10 year module warranty**