Hot panels can't even touch, is my wire size wrong?

[artvandaley]

At my cabin I have 2x120 watt 17.8 volts in circuit at 6.8 amps each Suntech solar panels on my shed that have a MC4 connectors, and I connected a 48 foot (48' from panels to battery) 8 awg wire with MC4 connectors to the panels which leads to a 20 amp fuse and then goes to a PWM 25 amp charge controller. Connected at the 20 amp fuse I have a 15 watt solar panel 21 volts in circuit at 1 amp with 12 awg wires 38' from the battery, wired to the 2x120 watt panel's 8 awg wires. I did this because in the winter the 2x120 watt panels will be covered, and the 15 watt panel is mounted Vertically so it can feed power to the 110 ah battery during the winter when nobody is at the cabin to clear the snow. From the 110 ah battery I have 6 lights totaling 24 watts with 12 awg wires and a 1000 Watt inverter with 2 awg wire (inverter to battery is 17'). Now when I connect the whole thing the wires never got warm and everything seems to work great. Can this make the solar panels so hot I can't even touch them for a split sec? I do have the panels in a wooden framed box covered by plexiglass to keep people from throwing rocks directly as the panel and branches from falling on the panels. I was wondering if this is the only reason why the panel would get hot.
I'm not sure if this can be viewed, but I have a pdf of what I have wired here, http://joeytclements.com/cabinmay2012.pdf
and the box here http://joeytclements.com/solarpanelshed.pdf

[Naptown]

Start with losing the box or the plexiglass above. Way too much heat build up in there. you are also losing 10-20% or more because of heat and losses through multiple glazing and air spaces.

You don't have a wiring problem you have a ventilation problem.

Another thought
Stick with the thermal and leave the PV alone.

[artvandaley]

Start with losing the box or the plexiglass above. Way too much heat build up in there. you are also losing 10-20% or more because of heat and losses through multiple glazing and air spaces.

You don't have a wiring problem you have a ventilation problem.

Another thought
Stick with the thermal and leave the PV alone.

Sorry, what do you mean, Stick with the thermal and......? I just thought maybe the 48' 8awg wire with the MC4 connection might have been a problem. You think the system is solid besides the box?

[Naptown]

Sorry, what do you mean, Stick with the thermal and......? I just thought maybe the 48' 8awg wire with the MC4 connection might have been a problem. You think the system is solid besides the box?

I may have mistaken you for another member with a similar name.

No the system is not solid you have a mismatch of module sizes and if wired the way I think they are all in parallel before the charge controller and you cover the 2 120's in the winter you are backfeeding to the 2 panels. creating only heat in the 2 120's and reducing the output of the little panel.

[artvandaley]

I may have mistaken you for another member with a similar name.

No the system is not solid you have a mismatch of module sizes and if wired the way I think they are all in parallel before the charge controller and you cover the 2 120's in the winter you are backfeeding to the 2 panels. creating only heat in the 2 120's and reducing the output of the little panel.

I see, so do you have any suggestions to how I should wire them? I am mostly worried about faulty wiring, and causing a fire.

BTW, thanks for responding to my questions.

[Naptown]

The 2 120's on one charge controller
the little one on a separate charge controller
Both CC's feed to battery.
The little one will only need a 5A CC

[artvandaley]

The 2 120's on one charge controller
the little one on a separate charge controller
Both CC's feed to battery.
The little one will only need a 5A CC

Yeah, I have a 7A CC that I'm going to hook up, I thought that would be the best idea as well. I just didn't want more wiring around the battery and thought it might be fine. Thanks for the advice. I am still nervous about the 8awg wire with the MC4 connection, but I think it's fine because the highest amp rating will be 13.6 amp (top rating). And I did a lot of calculations with online calculators with the 8awg wire 48' distance and the voltage drop seems to be around 4-5% at most with the Panel rating at 17.8 volt in circuit. Again, thanks for responding.