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position of extra string

  • 26-08-2022 9:11am
    Registered Users Posts: 137 ✭✭


    I have to option of another string of 4 panels.

    Panels faces ESE, so getting from sunrise, thru noon till afternoon when sun goes over to front

    Front faces WNW.

    Adding the string to the already in place panels is the most obvious, but I'm missing on 2-3 hours of light in the summer.

    Am i overthinking the placement?

    Thanks v much


  • Moderators, Sports Moderators Posts: 18,107 Mod ✭✭✭✭slave1

    What wattage is your current panels, are they on a single string, is your inverter MPPT?

  • Registered Users Posts: 137 ✭✭what?


    Panels 385

    Second string/MPPT, I don't know that, Installer tells me yes

    Model is MIN 4200TL-XE if that helps

  • Moderators, Sports Moderators Posts: 18,107 Mod ✭✭✭✭slave1

    Grand, I'm by no means an expert but if you have a string free (that Inverter is dual string) then all looks good, get as high a wattage panels as you can manage, as they are on a different string they do not have to be 385w

  • Registered Users Posts: 137 ✭✭what?

    Cheers Slave1!

    Does anyone have an opinion of the best position to face the panels?

    On the flat roof thay could be pointed due south, or on the front of the house have a more westerly orientation.

    i,e, bump up my daily production or elongate my catchment hours.

    Budget dictates one string only

    thanks v much

  • Registered Users Posts: 2,263 ✭✭✭bullit_dodger

    Pretty much always south. Those ENE panels would be effectively useless in winter, least with the South ones you'd get something from them.

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  • Moderators, Sports Moderators Posts: 18,107 Mod ✭✭✭✭slave1

    If West then they would be good for PV into the evening, I suppose a lot depends on your personal usage, if you have no battery what use is higher generation during the day if you are not there to consume it?

  • Registered Users Posts: 1,197 ✭✭✭DC999

    Adding to what others have said, if you've no battery then add to a new roof orientation (don't add more panels on the same orientation). Then you decide which orientation allows you use the power when it's available (West for evening / dinner time, or South for middle parts of day).

  • Registered Users Posts: 2,263 ✭✭✭bullit_dodger

    Fair points lads about being there to use it, but I was thinking in terms of FIT. If you put them on the WNW, then those panels are going to produce next to nothing in the winter. I know as I've East/West split myself and my West do very little. If you are even more north facing than West then you can expect nothing from late Oct to Feb.

    With south and FIT giving you "something" for anything you export that you might miss during the would seem the better choice - albeit, a lot of this type of stuff is down to personal preference and not right/wrong.

  • Registered Users Posts: 137 ✭✭what?

    Thanks v much for the replies folks

    tis true, I'd much prefer a right/wrong binary decision.

    That said, no battery, currently old backwards meter, I'm leaning to facing them south.

    Again ta very for the responses

  • Registered Users Posts: 2,263 ✭✭✭bullit_dodger

    Makes sense with a backward facing meter to maximise your output.

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  • Registered Users Posts: 1,197 ✭✭✭DC999

    Ah @bullit_dodger, ta for explaining that. I've NW on 1 roof so at least now I know I'll get SFA from that from the end of this month. Output on that is lowest compared to my SE and SW - that explains it. Every day is a school day in solar land :)

  • Registered Users Posts: 2,263 ✭✭✭bullit_dodger

    Ahh, you'll aways get "something" from them DC999, but it'll be diminishing a lot come Oct. For example, here's the expected output of 1Kwp in panels from NWN

    Compare that to 1Kwp facing due south

    You can see while in summer, they are reasonably close (the North west facing ones doing 80% or so the production of south), but in winter, the same panels only do about 20-30% of south.

    Good site to play around....'s%20the%20calculator%20for%20Europe

    (Don't worry it's not as daunting as it looks)

  • Moderators, Sports Moderators Posts: 18,107 Mod ✭✭✭✭slave1

    I have NW panels, they'll be frozen over for days at a time in the deepest of our Winter period

  • Registered Users Posts: 38,437 ✭✭✭✭Mellor

    Plan for the future. The pay back on north facing PV panels is pretty long.

    No battery now doesn't mean no battery in future, is selling it to the grid going to be out of reach forever.

    Maximise energy imo.

  • Registered Users Posts: 137 ✭✭what?