Why we use silver solar panel? Because black one absorb too much heat and will become very hot and reduce the efficiency of the solar panel drastically.
Our 5w solar battery charger can generate 10~20 Wh per day normally. Suitable to
work as a maintainer for a motorcycle battery, or as a maintainer for a car/boat battery which is less than 12v 40AH in area which has good sunshine.
If works as a battery charger, this panel can full charge a 12v 2AH battery in one sunny day.