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GaryS1953's avatar
GaryS1953
Nomad
Dec 04, 2017

ADD ANOTHER SOLAR PANEL

Hi Everyone,

I currently have 2 165 watt 12 volt solar panels in series going to my Renogy MPPT controller. I have unobstructed real estate for one more panel and would like to add another. Ebay sent me a good offer for a 175 watt 12 volt panel. Would there be any problem adding that panel in series to the existing panels? I think by doing this I wouldn't get the extra 10 out of the 175 watt panel, but would there be any other difficulties?

I appreciate any input.

33 Replies

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Dec 09, 2017
    I did the same thing, had two 160 watt panels and decided to add another, they just went into the existing take off that was up there. I have a go power system.

    Steve
  • GaryS1953's avatar
    GaryS1953
    Nomad
    Dec 08, 2017
    allen8106 wrote:
    The first question I would have is what's driving you to add panels?

    Second question is what is your battery bank?

    DW and I are going to be doing some dry camping during the winter months when there is less sun. I either need to tilt my panels, or add more to get fully charged with less sun. I've chosen to add another panel. I currently have 2 GC2 135 AMP hour batteries, with room to add 2 more if needed. So far no need as I don't use any high wattage items, and my little inverter only runs our 19" TV.
  • allen8106's avatar
    allen8106
    Explorer
    Dec 08, 2017
    The first question I would have is what's driving you to add panels?

    Second question is what is your battery bank?
  • pianotuna's avatar
    pianotuna
    Nomad III
    Dec 06, 2017
    Good plan,

    Unfortunately I have not been able to source panels with bypass diodes between each cell since UniSolar went under. I do freely admit they are HUGE as well. I'd love to have more wattage, but that would require starting over with a charge controller with greater capacity and new poly panels with an MPPT controller. (Yes, I know it is not economic).

    2oldman wrote:
    The problem seems to be the BP panel which gets shade from the a/c cowling. I made a mount that pulled it back some, but this time of year it doesn't get it out of the shade. I should put a switch on it to completely bypass it.
  • BFL13's avatar
    BFL13
    Explorer II
    Dec 06, 2017
    Even better if that back panel happens to be the mono one.
  • 2oldman's avatar
    2oldman
    Explorer II
    Dec 06, 2017
    The problem seems to be the BP panel which gets shade from the a/c cowling. I made a mount that pulled it back some, but this time of year it doesn't get it out of the shade. I should put a switch on it to completely bypass it.
  • BFL13's avatar
    BFL13
    Explorer II
    Dec 06, 2017
    2oldman wrote:
    I noticed my incoming voltage was around 75, which is low for 6 panels in series. I guess my next project will be getting panels like pianotuna has.. lots of bypass diodes.


    My idea back when, was to yank that back panel and make all five in series poly as a trial set-up to see if you do better than now. However you didn't want to bother since the way it is gets you enough to do the job.

    I still think the five polys no shade would do better for all day AH haul than the six panels in series with one shaded part of the day and one mono in the mix doing less in low light.
  • 2oldman's avatar
    2oldman
    Explorer II
    Dec 06, 2017
    I noticed my incoming voltage was around 75, which is low for 6 panels in series. I guess my next project will be getting panels like pianotuna has.. lots of bypass diodes.
  • BFL13's avatar
    BFL13
    Explorer II
    Dec 05, 2017
    2oldman wrote:
    I don't know. They're at least 5 years old.


    ISTR all poly except one mono. One panel in back getting shaded part of the day. JiminDenver posted about monos losing more in low light than polys so with one mono in series with polys you would lose extra in the shoulder hours from the mono setting the pace.

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