"Jim Wilkins" wrote in message
...

If it's the Harbor Freight panel kit you are lucky to get 30W from
it. The 45W rating is into a 17V battery. They deliver the same
current to a 12V battery.

I took a look at them while hanging laundry. Yes, it does dry in
freezing weather, just like roads and sidewalks.

Each panel is rated at 17.5V, 0.86A. The three add up to 45.15 Watts.
However that current into a 12.6V lead-acid battery is 32.5W. The
current is about the same into a short circuit, such as an ammeter.
They are stiff current sources (photon-to-electron converters) with a
compliance voltage around 22V. The charger in the kit is a series
switch that opens at 14.4V to prevent severe overcharging.
jsw