388W solar panel system

theno1katzmantheno1katzman Registered Users Posts: 9
Hi,
I am trying to keep the solar panels as small as possible because I need to mount them to the top of my van. The smallest size I came up with was 42.875x41.125 inches. Now for these panels I have 12 3x6 cells each rated at 1.8W 0.5V 3.6A in a series string and I'm using 1/4" spacing between them. I am going to want to tie 6 strings together in parallel using bus wire. That would bring me from 21.6W 6V 3.6A to 129.6W 6V 21.6A panels. Then I would wire the panels in series to get 388.8W 18V 21.6A.

I have CAD so I can post a picture of what they would look like if you need that.

So the cells were bought on ebay and the seller only gave me 5' of .152mm ga bus wire. This i looked up is 34 ga which I think is too small to carry the current through the entire panel. I need almost 18' of bus wire (to connect the strings on top and bottom for making the positive and negative sides of each panel).

My question is what brand of bus wire to get that has some solder on it already(if not then I would buy separately), and what size gauge of it, and if it is supposed to be copper or aluminum wire?
Thanks,
Seth

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,027 admin
    Re: 388W solar panel system

    I would assumed tinned copper bus wiring... Aluminum is not very easy or friendly to bond with electrical components except in very limited setups/crimped and sealed connections.

    I am not a huge fan of DIY solar panels. Have you looked at the various commercial panels out there and see if you can fit something at a reasonable price?

    Also, if you go with an MPPT charge controller, your Vmp can range from 18 volts to ~100 VDC (depending on the charge controller).

    Larger (>100 watt) panels tend to be much less expensive (and not have Vmp~17.5 volts for PWM controllers charging a 12 volt battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • theno1katzmantheno1katzman Registered Users Posts: 9
    Re: 388W solar panel system

    Hi Bill,
    Thanks for the quick reply. I can't really say. I already spent quite a bit on the cells, tabbing wire, etc, so this is the direction I am going in.
    Thanks again.
    Seth
  • BB.BB. Super Moderators, Administrators Posts: 32,027 admin
    Re: 388W solar panel system

    Here is some nice documentation by somebody on another forum who built their own panels:

    Oztules' series:

    http://fieldlines.com/board/index.ph...,144982.0.html
    http://fieldlines.com/board/index.ph...,144995.0.html
    http://fieldlines.com/board/index.ph...,145004.0.html

    Still don't recommend people build their own to save money--But some good information for those that want to try.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • theno1katzmantheno1katzman Registered Users Posts: 9
    Re: 388W solar panel system

    So after some more research my solar panel system has changed, and I won't be needing to know how to wire cells like that specifically, but I'm the type of person who can't just let unanswered questions remain unanswered, so I still would like to know what to do, if anyone has wired strings of cells together in parallel, what size bus wire do you use? Because the bus wire that comes I am sure is not strong enough to hold the current of more than two strings at once.
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