... low quality and fake power rates solar panel—for example 280W poly solar panel pretend 300W solar panel, use damager solar cell pretend A-grade sold to the customer ... --- Between 16-18.9% for solar cells.6. What is the Nominal Voltage --18V, so it can charge 12V battery., if you want ... 36V, so you can charge 24V battery, just loose the cable from the solar panel and connect them in series, if ...