Forum Discussion

evy's avatar
evy
Explorer
Apr 23, 2018

Planning solar panels (take 2)

Ok so my project is going forward but not as fast as I was hoping...

I am planning installing (2) 300w solar panels (600w total) on the roof of my DIY camper.

The thing is these 300w panels are huge 39"X60"!!
They take up a lot of space on my roof rack and I had an idea to save some space, by installing the two panels one on top of the other, but having the bottom one slide out on tracks and by doing this it would cover my windshield like an awning, that might be interesting on those hot sunny days.

But I heard (really not sure) that if you have shadows on only one of the two panels it affects the output? can anyone confirm?
So If I'm parked at a restaurant for a couple of hours and my bottom panel is not out (100% shadowed) what are the consequences?

FYI 600 watts for 2 6v batteries (225AH total) with a 40A MPPT Epsolar Tracer charge controler.

This is just an idea, let me know if it's a bad one and why, thanks guys!

If I install them side by side on my roof rack they take up 2/3 of the space :-(

p.s. the kayak will not be there often and if it is, It will only be there when rolling.



  • evy's avatar
    evy
    Explorer
    Apr 24, 2018
    time2roll wrote:
    BTW can you insert a space and width=640 at the end of your picture syntax.
    Easier to read.


    Done! thanks
  • time2roll's avatar
    time2roll
    Nomad
    Apr 24, 2018
    Alternator and vehicle wiring can't always get full 14.6 volts on the battery like the solar.
    Good to have both in transit.

    BTW can you insert a space and width=640 at the end of your picture syntax.
    Easier to read.
  • brulaz's avatar
    brulaz
    Explorer
    Apr 23, 2018
    evy wrote:

    ...
    when you travel isn't it your alternator that charges your batteries?


    Used to be strictly solar charging of my trailer's batteries until last summer when it rained all the time. Now I use both Solar and Alternator when travelling.

    Took another look at your picture, and you seem to be modifying a panel van, not a trailer. It's different with trailers cause the long distance from the alternator to the trailer batteries and the small wires provided by the truck make serious charging of trailer batteries difficult. Much less of an issue with your van.

    But anyway, all the trailer issues can be fixed, and I now have a system that can provide ~600W via the truck's alternator as well as ~690W via solar to the trailer's batteries. Best of both worlds.

    There can be a lot of solar available driving down the highway. No trees, and the wind keeping the panels cool makes for optimum conditions. Hate to waste it.:)
  • evy's avatar
    evy
    Explorer
    Apr 23, 2018
    brulaz wrote:
    I would put the panels length wise on one side of the trailer so the kayak won't shade them when travelling. We do a lot of battery recharge with solar when travelling.


    The kayak is drawn just to see if I can still physically fit it up there with the solar panels. It will almost never be there.

    when you travel isn't it your alternator that charges your batteries?
  • brulaz's avatar
    brulaz
    Explorer
    Apr 23, 2018
    I would put the panels length wise on one side of the trailer so the kayak won't shade them when travelling. We do a lot of battery recharge with solar when travelling.
  • evy's avatar
    evy
    Explorer
    Apr 23, 2018
    time2roll wrote:
    Yes any shade can make each section not produce power. These large panels are set in three sections. There are bypass diodes so the unshaded sections can still produce power. If going with an over/under configuration consider running them in parallel. Bottom panel will add power when extended. Make sure the slide mechanism gives you plenty of reach to completely expose the lower panel even when the sun is at an angle.

    What is the actual width of the platform? '8 wide RV can get two of those panels side by side. In which case I would mount them side by side in the rear. Again in parallel with one getting shade when the kayak is mounted.

    As shown both panels will produce about nothing when the kayak is up.


    The kayak is drawn just to see if I can still fit it up there with the solar panels. It wont be there too often.

    The width of the roof rack is 66"
    I can't fit two of those side by side that's for sure.

    I was considering getting extra long 48" drawer slides, the panel is 39" wide so there would be a 9" space between the panels when it is totally extended.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 23, 2018
    Yes any shade can make each section not produce power. These large panels are set in three sections. There are bypass diodes so the unshaded sections can still produce power. If going with an over/under configuration consider running them in parallel. Bottom panel will add power when extended. Make sure the slide mechanism gives you plenty of reach to completely expose the lower panel even when the sun is at an angle.

    What is the actual width of the platform? '8 wide RV can get two of those panels side by side. In which case I would mount them side by side in the rear. Again in parallel with one getting shade when the kayak is mounted.

    As shown both panels will produce about nothing when the kayak is up.

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