Why Such Wide Voc Difference ??? Am I Going to Fry Everything ???

WowabungaWowabunga Posts: 7Registered Users ✭✭
Help...!!! Just picked up some 24v 180watt panels from a Craigslist seller and got them dirt cheep at $25 a panel.

Was about to mount the new Suntechs when I find that the overall output is substantially more then my current Evergreen 24 volt panels.  I'd really like to tie them all together and power some more grow lights in my greenhouse.

My current charge controller is a Morningstar 15 amp and will mothball that unit.   Will be using a new Xantrex C-35 35 amp controller if you folks think it's safe to combine 3 evergreen panels with 2 of these suntechs ???  Help ???

Thanks,
Ramblin Randy


Comments

  • littleharbor2littleharbor2 Posts: 1,026Solar Expert ✭✭✭✭
    edited April 5 #2
    The Evergreen panels are not 24 volt panels Have they been in service charging a 24 volt battery bank?
     The Suntech are 72 cell panels, which are considered 24 volt nominal. They have high enough voltage, even when hot to properly charge a 24 volt battery.
     The 120 cell Evergreen Module is composed of 120 cells in a series/parallel configuration with voltage output similar to an older 60 cell module, which are considered a 20 volt, nominal module.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • WowabungaWowabunga Posts: 7Registered Users ✭✭
    littleharbor2 that info about the Evergreens sure is interesting.  They are on loan from my Dad who had a few extra when he installed his professional roof system.

    I've been using a Morningstar MPPT controller on a  24v bank of golf cart batteries.  They seem to be charging the batteries to 28v just fine.

    Looks like I better not hook the two different makes together.  I'm thinking I should just hook up 7 of the Suntechs ( I have 8 total ) and be happy with the upgrade to a 1260v system which will supply all my needs for now.



  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    Combining the two types of panels on a single controller is probably a bad idea. They have different enough voltages that a single controller will have trouble dealing with them in a single array.

    You could, however, keep the existing array on the existing controller, and add the new array on a new controller, with both controllers charging batteries and running loads in parallel.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Posts: 4,701Solar Expert ✭✭✭✭
    On a 24 volt system, you will need an MPPT type charge controller to use the Evergreen's properly. 7 of the Suntechs on the C35 shouldn't be a problem. Could even put the other Suntech on the small charge controller.

    Oddly I have pretty much the same panels! I have 200 watt ES-E Evergreens and 185 watt Suntech (on 2 different systems, though I'll add some Suntechs on a different charge controller to my home system. @littleharbor2 described it so well, I had nothing to add...


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • WowabungaWowabunga Posts: 7Registered Users ✭✭
    Ok Photowhit.... I was told the Evergreens were excellent panels also.  Is it the "string-ribbon" technology that allows them to  have a low Voc of 35.2v and still charge my golf cart 24v bank?  

    And here's the fun fact of the day... the guy on Craigslist was originally was asking $100 per panel but no one local wanted 24v panels.  After several weeks he decided to blow them out and sold all 8 for $200 bucks.  I just happened to see it when the price dropped and It was like 12 degrees out when we hauled butt up the road about 30 miles away.  Nothing better than a crazy deal on solar.  Now this summer I'll have enough solar to run one 500w AC unit.  I can't wait...!!!
  • PhotowhitPhotowhit Posts: 4,701Solar Expert ✭✭✭✭
    i would actually suggest you aren't properly charging your batteries. Perhaps you are using AGM batteries and have never equalized? I have a 24 volt system and charge my catteries at 29 volts and Equalize at 31.

    7 - 180 watt panels will be nice, 1260 watt array, but don't expect to get much air conditioning. Try your best to get the other 3 panels added to your system. You can use multiple charge controllers on the same battery bank, but you are running pretty close to the effective charging capacity for 4 - 6 volt golf cart batteries (If that is what you have).

    I've air conditioned with a similar system. I would suggest a smallish, well insulated room. Try for something in the shade. Balancing the cooling during the day after batteries have reach float, and late in absorb. with the battery capacity to run off the storage into the evening. I would have the air conditioner on a timer to turn off at some point during the night. Many air conditioners have a timer built in these days.


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • littleharbor2littleharbor2 Posts: 1,026Solar Expert ✭✭✭✭
    Wowabunga said:
    littleharbor2 that info about the Evergreens sure is interesting.  They are on loan from my Dad who had a few extra when he installed his professional roof system.

    I've been using a Morningstar MPPT controller on a  24v bank of golf cart batteries.  They seem to be charging the batteries to 28v just fine.

    Looks like I better not hook the two different makes together.  I'm thinking I should just hook up 7 of the Suntechs ( I have 8 total ) and be happy with the upgrade to a 1260v system which will supply all my needs for now.




     So when you mentioned you were going to mothball the Morningstar 15 amp controller I figured it was a PWM controller. Now you mentioned it was an MPPT controller. Did you have the panels series wired? 

     Yes, the Evergreen panels are regarded as very good panels but the string ribbon cell technology really doesn't give them any superior charging abilities.  

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • WowabungaWowabunga Posts: 7Registered Users ✭✭
    Today my 4 Interstate golf cart batteries (series) were charged at 29v with no load.  I did notice that when I turned on my T-5 grow light fixture that uses 325 watts... I measured the batteries in use at 26.5v and with a estimated  400 watts coming off the roof maybe there is some truth to what I'm being told.

    Glad to know I can use different charge controllers on the same battery bank.  That's all good except for maybe if they want to auto equalize, so I'll set them both for manual.

    This old farm house for insulation has some horse hair in the walls I think LOL.  In winter I just use a big bad wood stove and all is good.  This summer I will take advantage of bright sunny days for the free AC and at night will just suck it up and plug into the grid.  Thanks for all the advice and direction.  I've been toying with solar since 1998 and this week will be the first week that I go over the 1000w array milestone.

  • littleharbor2littleharbor2 Posts: 1,026Solar Expert ✭✭✭✭
    You still haven't mentioned if the Evergreen panels are series wired. That would make sense as far as your battery bank charging to 29 volts. I just cant see 15 year old panels that are rated at less than 29 volts, in parallel,  charging as you say

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • PhotowhitPhotowhit Posts: 4,701Solar Expert ✭✭✭✭
    ...I just cant see 15 year old panels that are rated at less than 29 volts...
    Good question, Evergreen sold off it's assets in 2011, so need not be 15 years old...lol.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • WowabungaWowabunga Posts: 7Registered Users ✭✭
    I'm going to have to put the brakes on for a week or so,  I need to invest in some larger fuses and add more grounding.  Going past 1000 watts sounds fun... and dangerous too.  I'll be back soon.... thanks for the hand holding advice...!

    The 3 Evergreens are wired in plain parallel.  Once a load was placed on them they do dip down. 
    Odd that a company would make a panel with a power rating so far off the norm.  My father's 16 panel Evergreen system is in series and was a professional install so I guess they knew what they were doing.
  • PhotowhitPhotowhit Posts: 4,701Solar Expert ✭✭✭✭
    Wowabunga said:
    Odd that a company would make a panel with a power rating so far off the norm.   
    Not odd at all, the majority of panels are made for grid tied systems. Either large house hold systems or large solar farms. These work at higher voltages, so it is pure economics. What can be made cheapest. 60 cell panels were the ticket. In more recent times, they've figured out how to make even larger panels that are 72 cell panels like your Suntech. In fact the Suntech was a bit of an odd ball when most panels that size were 60 cell panels. 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • littleharbor2littleharbor2 Posts: 1,026Solar Expert ✭✭✭✭
    edited April 6 #14
    The Suntech is a 72 cell panel similar to say, a BP4175. They are composed of 5" cells and are about 31 x 64" My array in Baja is made up of Suntech 175's

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • littleharbor2littleharbor2 Posts: 1,026Solar Expert ✭✭✭✭
    The Evergreen panels are composed of 3" x 6" cells. Mobil Solar produced an odd module which also had a high number of 3" x 6" cells with multiple parallel strings and a 6 volt nominal rating Putting out a Vmp of just over 10 volts. That format didn't catch on for some reason. I wonder if it was because of the high amp rating which was around 22 amps

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

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