Getting technical, 15 watts is not enough to prevent and reverse sulfation in larger lead acid batteries, the problem that makes this product important.

However, with the battery known to be full (charged with the ac version of this product), the solar charger at the decent 10 watt always showed a yellow charging, after 2 straight days of solid sunshine and never went to a green fully charged status

5 watt is great for maintaining a motorcycle or small import car to keep battery topped off while it is sitting and not in use, but, this solar panel is lacking any real charging capability

20 watt is as low as I would buy and I would highly recommend a 30 watt or above system

but I got a reliable 12+ watts under ideal conditions.)

10 watt might be better but this works good for me.

10 watt might be better but this works good for me.

Getting technical, 15 watts is not enough to prevent and reverse sulfation in larger lead acid batteries, the problem that makes this product important.

Works as it supposed to.

Sometimes seems to work ok sometimes, but it's really hit or miss as to whether the battery is actually charged when the light on the charger says it's charged.

Has worked as I had hoped so far, I will update my review if I have any issues

n’t work

n’t work