Solar Power Feedback

Yep

:)

Yes. In my experience you never get the full rated power from the panels, but you will get the best you can. Trust you have a good controller so the batteries are not overcharged.

cheers
alastair

short answer, yes.
little bit longer answer :)
power ( watts ) = Voltage ( Volts ) * Current ( Amps ).
with two 80W 12V panels
in parallel you'd have 80+80 = 160watts = 12V * 13 1/3 amps
or in series you'd have 80 + 80 = 160 watts = 24V * 6 2/3 amps ( half the current and twice the voltage ).

general rule is parallel ( same voltage of course ) current = sum of individual panel current and power = sum of individual panel power.
for series ( same current panel ) voltage = sum of individual panel voltage and power = sum of individual panel power.

Jfoggy,

I'll run the risk of being broadsided from both directions!

Two 80W panels will NOMINALLY deliver 160W. By connecting them in parallel you'll double the CURRENT output, keeping the same voltage output - just what you need for charging a 12V battery. Important to have a controller to disconnect the panels from the battery once it is fully charged.

Mike's comment about current is absolutely valid. The manufacturers obviously rate their panels as high as possible. In fact the maximum power output occurs at about 17-18 volts. We cannot apply more than about 14 volts to a battery when charging. The 80W specified for each panel (watts = volts x amps) occurs at say 18V so we can calculate the maximum amps as 80/18 = about 4.5 amps as Mike says. If we can only use a maximum of 14 volts then, the maximum power delivered to the battery is 14 x 4.5 = 63 watts.

(I don't want to confuse the issue by talking about MPPT controllers, which use switchmode technology to improve this figure a bit at considerable expense. Almost all rigs I've seen use simple controllers and users simply accept that the useful power is significantly less than manufacturer's rating.)

Your two 80W panels connected in parallel and fed through a controller to the battery should deliver up to about 9 amps. This is very similar to our own setup. Recommend placing the controller at the battery rather than at the panels, so that any losses in the cable occur before, not after, the controller.

You may be interested to explore some more detail in our blog Electricity for Camping

HTH

John