Upgrading.. need opinions please

Current system below... 12V

I'm wanting to upgrade battery capacity & solar panels.

Thinking about the following:

Adding an additional panel 140 Kyocera (410 watts total)
Upgrading charge controller to Morningstar Prostar 30amp

3 options on upgrading batteries..

1. Keep the 2 Trogan T105RE (2yrs old approx) & Add 2 more (450 a/h total)
2. Replace 2 Trogan T105RE w/ 2 L16REA (325 a/h)
3. Replace 2 Trogan T105RE w/ 2 L16REB (370 a/h)

Based off the formula I believe to be true.. 1. 4.5% charge rate 2. 6.7% charge rate 3. 5.9% charge rate. (6.4% charge rate currently and seems to be ok with current batteries)

I think I would be happiest with either added 2 more 105's or the larger L16B. What are you guys thoughts?

Also the backhaul to the charge controller is a 25' MC4 10 gauge wire.. will this still be ok with 410 watts/12v panels?

Thanks!

Chris

Comments

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Upgrading.. need opinions please

    What are your loads? load dependant you probably need more PV to get a better charge rate. 10% is a good target.

    As to the upgrade are the 2 panels you have 140W, if so 3 x 140 = 420W
     
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Upgrading.. need opinions please

    Batteries are usually sized to support loads. If your current batteries are not enough to support your loads, you need to add more. If they're Ok, it is nothing wrong with adding more panels without upgrading your batteries.

    If your loads are such that you feel you need 400AH array then you probably will need more panels than you're planning on. In this case, your system is getting bigger and you may want to think about converting to 24V.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Upgrading.. need opinions please

    400 watts is not going to be enought to properly charge 4 L16s. As Eric said, the loads determine the battery bank size, the battery bank size determines the PV size etc. 450 ah of battery wants to see about 50-60 amps.

    Good luck and keep in touch,

    Tony
  • spanel
    spanel Solar Expert Posts: 36 ✭✭
    Re: Upgrading.. need opinions please
    icarus wrote: »
    400 watts is not going to be enought to properly charge 4 L16s. As Eric said, the loads determine the battery bank size, the battery bank size determines the PV size etc. 450 ah of battery wants to see about 50-60 amps.

    Good luck and keep in touch,

    Tony

    I was only thinking about 2 L16's....

    Do you guys think that my wiring will be ok to support 3 panels?

    Thanks

    Chris
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Upgrading.. need opinions please

    Option #1 gives you 450 Amp hours @ 12 Volts. Wants 45 Amps peak current which requires 788 Watts of panel on a PWM controller capable of 50+ Amps.

    Option #2 gives you 325 Amp hours @ 12 Volts. Wants 32 Amps peak current which requires 560 Watts of panel on a PWM controller capable of 40+ Amps.

    Option #3 gives you 370 Amp hours @ 12 Volts. Wants 37 Amps peak current which requires 648 Watts of panel on a PWM controller capable of 40+ Amps.

    If the L series batteries don't get their full charging power they will have a much shorter life. There is no sense in planning on minimal charge current and expecting the system to work.

    None of these options will work with a 30 Amp charge controller. None of them will work with only 410 Watts of panel. None of them will work with 25' of 10 AWG between array and controller (the current is too high, the Voltage too low, the power loss too much). You could go with a more expensive MPPT type controller to reduce that power loss by using higher array Voltage. In fact I'd recommend it, given the size of the array, but for utilizing the existing panels (gets very expensive).

    Time to rethink the plan. Broken record: start with the load demands and determine the battery bank capacity by that. Then size the array & controller to properly recharge the batteries. Doing it any other way results in disappointment.
  • spanel
    spanel Solar Expert Posts: 36 ✭✭
    Re: Upgrading.. need opinions please
    Option #1 gives you 450 Amp hours @ 12 Volts. Wants 45 Amps peak current which requires 788 Watts of panel on a PWM controller capable of 50+ Amps.

    Option #2 gives you 325 Amp hours @ 12 Volts. Wants 32 Amps peak current which requires 560 Watts of panel on a PWM controller capable of 40+ Amps.

    Option #3 gives you 370 Amp hours @ 12 Volts. Wants 37 Amps peak current which requires 648 Watts of panel on a PWM controller capable of 40+ Amps.

    If the L series batteries don't get their full charging power they will have a much shorter life. There is no sense in planning on minimal charge current and expecting the system to work.

    None of these options will work with a 30 Amp charge controller. None of them will work with only 410 Watts of panel. None of them will work with 25' of 10 AWG between array and controller (the current is too high, the Voltage too low, the power loss too much). You could go with a more expensive MPPT type controller to reduce that power loss by using higher array Voltage. In fact I'd recommend it, given the size of the array, but for utilizing the existing panels (gets very expensive).

    Time to rethink the plan. Broken record: start with the load demands and determine the battery bank capacity by that. Then size the array & controller to properly recharge the batteries. Doing it any other way results in disappointment.

    Let say I went with option #2.. and added 2 panels for a total of 560watts of PV. Is there a way to hook up the 4 panels to output 24volts to run down my 10gauge run, then convert that to work on my 12v system?

    Thanks!

    Chris
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Upgrading.. need opinions please
    spanel wrote: »
    Let say I went with option #2.. and added 2 panels for a total of 560watts of PV. Is there a way to hook up the 4 panels to output 24volts to run down my 10gauge run, then convert that to work on my 12v system?

    Thanks!

    Chris

    Yes; you would need an MPPT type controller. They can down-convert the higher Voltage to greater charge current. In this case you would be looking at over 35 Amps maximum current out of the controller, so you would need a minimum of a Morningstar TriStar 45 Amp MPPT: http://www.solar-electric.com/motr45ampmps.html

    As you can see that's over $400. But it would change the array output so that the 10 AWG would handle it with a bit over 3% V-drop over 25 feet.
  • spanel
    spanel Solar Expert Posts: 36 ✭✭
    Re: Upgrading.. need opinions please

    If I go that route.. would it make more sense to put the 2 existing panels in series and buy a Kyocera 220 watt panel to add to it?

    Thanks

    Chris
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Upgrading.. need opinions please
    spanel wrote: »
    If I go that route.. would it make more sense to put the 2 existing panels in series and buy a Kyocera 220 watt panel to add to it?

    Thanks

    Chris

    No; the KD220 has a very low Vmp of 26.6. It would not be compatible with two KD140's in series producing a Vmp of 35. Most of the cheaper-per-Watt 'GT style' panels have a Vmp around 30-ish, which is still low to be used efficiently in parallel with the 35 Vmp string.

    I don't know how much you could sell the existing panels for, but it might be worth investigating and then replacing the whole array and controller. I know: you do not need that kind of expense on top of buying batteries! :cry: This is, in a nutshell, the whole problem with system expansion.