Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

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Anima Center
Anima Center Registered Users Posts: 16
Greetings everyone, from Anima Nature Awareness and Herbalism school... a wildlife and botanical refuge 7 river crossings form pavement in the Gila Wildlands of SW New Mexico. We purchase our current Morningstar 30 controller, half our batteries and a couple of our solar panels from NA Wind & Sun, and discovered some very informative stuff here doing google searches. I do some writing about alternative energy in this work, another reason besides our personal solar quandary, for joining this forum.

As for what we need help with, recent readings have shown that for 15 years we have been using exactly the kind of solar system that's not recommended: mixed wattage panels hooked up positive to positive to make 12 volts, feeding mixed batteries. It's a wonder we have done so well, though our load is minimal: never more than 10 amp hours of load, for satellite internet, laptops, tunes and lights. Our batteries are 2 to 3 years old, 8 large wet cell 6volt golf cart batteries, and 8 of the advanced gel cell batteries from NAWS. My understanding is that while not an ideal situation, a controller can be set for wet batteries and still get the gels up to full, which is how we set ours. None are weak or defective, so batteries at least aren't the problem.

Main Problem That Started All This:
What inspired my foot dragging research was the fact that even with all this battery storage, we could go from blinking green on the controller all afternoon to yellow by midnight, using the 10 amps per hour described. Why, if their is no weak link in the battery bank and it's been sunny? Help!

Doesn't seen like the controller or panels could be the problem either... though it's becoming clear that see we need to rearrange the panels and get a larger controller.

Controller Question:
I was considering a BZ500 MPPT controller because they say they work well even with mixed panels, but now I read that there is no MPPT advantage when the panels aren't all the same... and ready also that BZs get slammed. An alternative would be the non-MPPT Morningstar TriStar 45 or 60. Advice please?

Panels:
Our courses, books etc. are offered on a donations basis and our income is mighty sketchy, meaning we can't consider replacing a majority of the panels in order to have them all be the same manufacture and Open Circuit Voltage as recommended. If I am reading right, the next best solution would be to split them into "strings" of similar panels, then combine them positive to negative to make 48 volt to the controller? Then run the lowest power string furthest out from the batteries, the strongest closest?

We have 3 racks of panels now, 9 total, run parallel (??-- pos to pos, staying 12v but increasing amperage). Now we want it rearranged into matched strings, then raised to 48V? This hodgepodge is the result of gifts from tree huggers, sales at NAWS, and trades for antique firearms... so don't laugh too hard:

Rack 1
1 Astropower: 75W–17.0V–21V OCV–4.4A
1 Evergreen: 120W–17.6V–21.5 OCV–6.82
1 Kyocera: 120W–16.9V–21.5 OCV–7.10A
Rack 2
3 Pacific Panels,Each:20W–16.05V–22.6 OCV–1.25A
1 Solarex Unmarked 20-35W?
Rack 3
2 Shell Panels, each: 85W–17.2V–22.2 OCV–4.95A

We depend on our system for everything, and would really appreciate your help in getting it straightened out before the sun disappears during monsoons.

Best,
Jesse Hardin & Kiva Rose
Anima Lifeways & Herbal School
www.AnimaCenter.org
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Off hand I'd suspect chronic under-charging leading to premature battery bank failure; it no longer has the capacity to hold a charge through the night. But as we don't know the Amp/hr capacity of your battery bank it's hard to say.

    BZ controllers are crap; don't waste your money.

    Your array with its mix of panels probably won't get much MPPT benefit. You might be better off to re-align the panels with separate controllers like this:

    120W Kyocera & 120W Evergreen (240W)

    2 Shell 85W & 75W Astropower (245W)

    All smaller panels together (80W)

    Then use 3 separate PWM type controllers for the three arrays.

    But knowing the battery bank size is essential to determining the proper charge set up. And knowing your loads (measured with a Kill-A-Watt) is essential to sizing the battery bank. Loads will also determine what size inverter you need and whether or not you should go to higher system Voltage.
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Then use 3 separate PWM type controllers for the three arrays.

    I fail to see the benefit in this. PWM controllers cannot MPPT, they just cut-off charging current to prevent battery overcharging. Paralleling all panels on one PWM controller should have same effect.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    AntronX wrote: »
    I fail to see the benefit in this. PWM controllers cannot MPPT, they just cut-off charging current to prevent battery overcharging. Paralleling all panels on one PWM controller should have same effect.

    Nothing to do with MPPT. It has to do with maximizing the output from three very different arrays whose Vmp & Imp are not very similar.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Welcome to the Forum!

    First, regarding your panels. At least the ones you have voltage/current listed for--they will all do fine when connected in parallel to either a PWM or MPPT type controller--And for now, if you have a functioning PWM controller--I would just stay with that one for the moment.

    If you wanted to go with a 24 volt battery bank--You can probably do OK with most of the panels you have now--but you may loose a couple because you don't have "pairs" of panels with similar enough Imp (current) that you can put in series.

    All told, you have ~565 Watts of power at ~16-17 volts Vmp and almost 32 amps.

    So, on really clear sunny days, you should see pretty near 32 amps maximum from your array (when the batteries are low).

    Using the PV Watts website and Tuscon AZ as being representive of the weather in your area... using 1 kW (sorry, smallest number program will accept), and 0.52 derating (panels, controller, battery bank, inverter losses) we get:
    "Station Identification"
    "City:","Tucson"
    "State:","Arizona"
    "Lat (deg N):", 32.12
    "Long (deg W):", 110.93
    "Elev (m): ", 779
    "PV System Specifications"
    "DC Rating:"," 1.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 0.5 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 32.1"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 8.5 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 5.70, 85, 7.23
    2, 6.11, 80, 6.80
    3, 7.03, 103, 8.76
    4, 7.50, 104, 8.84
    5, 7.29, 100, 8.50
    6, 7.15, 94, 7.99
    7, 6.44, 87, 7.40
    8, 6.85, 93, 7.91
    9, 7.06, 95, 8.07
    10, 6.72, 96, 8.16
    11, 5.99, 86, 7.31
    12, 5.27, 80, 6.80
    "Year", 6.59, 1105, 93.92

    For example, June would be 94 kWHhrs per month per 1kW of solar panels or:
    • 94 kWH per month * 0.535 kW of solar panels * 1/30 days per month = 1.68 kWH per day (June) = 1,680 WH per day
    • 1,680 WH per day / 12 volt battery bank = 140 AH per day (at 12 volts)
    So, if you are drawing 10 amps continuous load then an "average day" in June, you would be able to run your 10 amps of load:
    • 140 AH / 10 amps = 14 hours per day loading
    So, roughly, you would be able to power your 10 amp loads for ~14 hours per day this time of year--all things being equal and the system running correctly.

    I am not sure how to evaluate the mixed chemistry battery bank--Generally mixing batteries is not a good idea... In the case of AGM's they run at a slightly higher voltage and may take most of the load. The Lead Acid may not cycle as deeply (i.e., the AGMs will have to discharge quite a bit before the Lead Acid support the load)...

    With flooded cell batteries, you can measure the Specific Gravity of all the cells to see if you are getting them fully charged, and check a couple cells at night to see how far you are discharging.

    For AGMs, you can only measure resting voltage (with an accurate Volt Meter or Digital Volt/Multi-Meter) to estimate their state of charge.

    Regarding bank capacity--The golf cart sized batteries may be 6 volt 225 AH or so. There capacity at 12 volts should be 4x225=1,000AH.

    I don't know the AH capacity of the AGM...

    The reason for this question (AH capacity) is that you should balance both your loads and your solar panels to the battery bank. Too large of bank is difficult to recharge. Too small of bank will cycle below 50% capacity too often (and give you poor battery life).

    Also, I am not sure how much load you really have... We need both the Amps and the Hours you are running the loads... For example assume that you use 4 amps for a few hours, then 10 amps for a few more hours--they add up as:

    4 amps * 5 hours = 20 AH
    10 amps * 12 hours = 120 AH
    =======================
    Total Amp*Hours = 140 Amp*Hours
    • Amps (and Watts) are "Rates" (like miles per hour, gallons per minute).
    • Amp*Hours (and Watt*Hours) are "amounts" (like total miles driven, gallons pumped)
    • Amps*Hours and Watt*Hours are related by:
      • Watt*Hours = Amp*Hours * Voltage (typically battery bank voltage)
    Now, other things to consider--Operating an off-grid system is an exercise in extreme conservation. For example, you may have a pretty efficient AC inverter or 12 volt DC computer adapter--But when the AC loads are turned off or the Laptop is fully charged--there is still some current drain to operate the inverter/power supply electronics.

    Normally, you need to turn of the DC to these power adapters to prevent them from discharging more power when they are "on standby".

    Some things to read:
    You may need some more instrumentation to debug and monitor your system performance.
    The kill-a-watt and DC amp*hour/watt*hour meters are very useful to measure your loads over time.

    The DC clamp amp meter is very handy to measure the DC current from each solar panel (see if they are working well or not). And, you can measure the current throughout your battery bank and find which batteries are carrying the most load/charging currents and which are doing nothing.

    Anyway--my two cents worth.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    Main Problem That Started All This:
    What inspired my foot dragging research was the fact that even with all this battery storage, we could go from blinking green on the controller all afternoon to yellow by midnight, using the 10 amps per hour described. Why, if their is no weak link in the battery bank and it's been sunny? Help!

    It's good to monitor energy going into solar system and energy that's coming out. You have to watch battery voltage as you discharge it. Two of DOC Wattson model R102 digital panel meters will do the job. Connect one meter between charge controller and battery, second meter between battery and loads. Then watch how many Watt/hours were captured by solar panels, and how many got used by your loads. This instrumentation will allow you to diagnose problems with low output from solar panels, problems with batteries and will keep you from using more energy that was harvested.
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    Nothing to do with MPPT. It has to do with maximizing the output from three very different arrays whose Vmp & Imp are not very similar.

    All those panels are already running way below their maximum power points. So it does not matter if all panels are wired in parallel to one battery or if there are 3 sets wired to same battery through 3 separate PWM controllers. Going with 3 controllers would be a waste of money. All of Anima Center's panels are around 16 - 17 Vmpp. They will not run higher than 14.6 Volts, unless during battery equalizing. Because of that, all panels are running at maximum current. I may not be clear, so let me know if I can explain it better.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Moot point, but not necessary:

    8 "golf cart" batteries on a 12V system is likely 900 Amp/hrs of battery plus the gel cells (or AGM?)

    565 Watts of panels will never properly charge them. Result; quickly ruined batteries with severely depleted capacity - hence the yellow LED before midnight.

    The basic math:
    565 W @ 80% = 452 / 14.2 V = 31.8 Amps - enough for 636 Amp/hrs at best. Unless these batteries have been regularly recharged/equalized from another higher current source (i.e. generator) they are likely sulphated now.

    BTW, charge specs for FLA's, AGM's, GEL's are not the same, so even if there were sufficient power one or the other type would suffer in charging for having the wrong Voltage/current/time.

    I'd suggest measuring the Specific Gravity of the FLA's with a hydrometer and seeing how bad off they are.
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    565 Watts of panels will never properly charge them.

    I keep seeing this repeated on this forum. Maybe because I only use sealed AGM batteries, this advice make little sense to me. I have 14 Amps (360 Watts) flowing from charge controller and 520W array these days due to summer heat and mounting angle being slightly off. I am charging about 440 Ah of sealed AGM batteries. I use 0.5 - 1 KWh per day. I harvest 1.5 - 2.4 KWh per day. By about 2pm my diversion controller is dumping 10A into waste heat. Only 4A is flowing into 440Ah bank and this little current is enough to keep batteries at their cutoff point at 14.45V. So, 4A would be enough to fully charge 440Ah battery bank, it would just take longer.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    More or less, the reasons I try recommend 5% minimum for flooded cell batteries:
    • recommendation for equalization current by Rolls/Surrette (and probably others)
    • enough current to equalize/mix electrolyte in tall batteries
    • as Flooded Cell batteries age, they can discharge at a rate of 1-2% per day... Assuming you have 6 hours of full sun--that is 1/4 of the day to recharge the battery bank--you are looking at needing 4-8% rate of charge just to keep the old (typically forklift type) batteries charged from self discharge.
    Obviously, the 1% per day losses from an old battery bank is pretty much time to time replace the bank unless you got a bunch of excess solar power available to keep them going.

    Old AGM's are down in the range of 1-2% self discharge per week, never require mixing of electrolyte, and should never to equalized (at higher current/voltage like for a flooded cell bank). So--their minimum charging current can be much less.

    Anyway--probably let Jesse and Kiva recharge their battery bank so they can read the posts and reply back later. We don't want to get too far ahead of them. ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    AntronX wrote: »
    I keep seeing this repeated on this forum. Maybe because I only use sealed AGM batteries, this advice make little sense to me. I have 14 Amps (360 Watts) flowing from charge controller and 520W array these days due to summer heat and mounting angle being slightly off. I am charging about 440 Ah of sealed AGM batteries. I use 0.5 - 1 KWh per day. I harvest 1.5 - 2.4 KWh per day. By about 2pm my diversion controller is dumping 10A into waste heat. Only 4A is flowing into 440Ah bank and this little current is enough to keep batteries at their cutoff point at 14.45V. So, 4A would be enough to fully charge 440Ah battery bank, it would just take longer.

    The reason that people recommend ~5-13% of ah capacity charge rate (for FLA, AGMs are a bit different) batteries is twofold. One is to ensure that the batteries don't get chronically undercharge, but so that they charge at enough current to sufficiently stir up the electrolite so that the electrolite doesn't stratify in the cells.

    Your situation is nearly identical to mine. I charge at 15-20 amps into 450 ah of batteries, which is just at the 5% threshold. I also use ~600 wh/day, and by 2 PM I am floating. (Or more correctly, the batteries are!)

    http://www.batteryfaq.org/

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

    These links will provide a wealth of information about the "care and feeding" of batteries.


    T
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    I was trying to make that point about the different charge characteristics between battery types, and failed miserably. Not enough naps in a day!
    Thanks for the clarification, guys! :D

    The charge dilemma is something like this:

    10 Amp hours use per day @ 12V = 120 Watt hours.
    With a 100 Amp/hr battery and 150 Watt panel:
    150W @ 80% = 120 W in 1 hour, replacing used energy no problem.
    120W / 14.2 V charging = 8.4 Amps, enough to keep the FLA battery mixed and minimize sulphation.

    Now switch up to 3* the battery, 300 Amp/hrs, and same 150 Watt panel:
    Still enough power to replace the 10 Amp/hrs used every day.
    But 8.4 Amps is only 2.8% of 300 Amp/hrs; the battery sulphates, stratifies, and its capacity goes down as the sulphur acts as insulation on the plates. Less exposed plate area = smaller available capacity.

    AGM's do suffer from sulphation, but no place near as severe as FLA's and the "starved electrolyte" design prevents problems with stratification. The difference of a small amount of "liquid conductor" (electrolyte) trapped between plates and a big ol' vat a chemicals that has to be kept stirred.:p
  • Anima Center
    Anima Center Registered Users Posts: 16
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Thank you everyone. We're impressed with your comprehension of what seems to be rather complex issues. As writers and artists we struggle with even basic math and rudimentary mechanics! If anyone here needs herbal knowledge or a custom logo, we excel at such impracticalities... :)

    Load:
    I have no Kill-a-Watt for measuring load (will buy a couple for sure!), but the Morningstar 30 Controller shows us using a consistent 8 to 10 amps for 15 hrs a day. We use DC led lights, 12v car stereo, two new mac laptops, etc., only use small DC to AC inverter for powering the satellite internet box.

    Array Output:
    The controller also shows we get about 31 amps in full sun from the array.

    Battery Inventory:
    7 SunExtender PVX 840T (about 3 years old)
    8 Trojan T-105 (2 years old)

    We used a hydrometer and did load test on Trojans and they are fine it seems.

    We seem to have a LOT of battery capacity for our purposes, but BB, are you saying we should only be able to get 14 sunless hours worth of power at 10 amps steady use out of all 15 batteries. One friend said this amount of storage should power us for days of no sun, given our meager load. The math makes my head spin.

    Is it possible to isolate the wet batteries and AGMs, and still have them both charge from the same system?

    Further Questions:

    Confused even with the advice, but that could just be me. How could our batteries be chronically undercharged, Coot, if the controller shows them in Green with 14v reading in sun and 12.7 at night? And how could such a large battery bank drop to a low enough percentage for the controller to switch to a Yellow light, after only 6 or so hours of use at only 10 amp draw??

    Is there any advantage to an MPPT controller, when there are mixed panels?

    Can it be agreed as to what the best pairings or strings of panels would be, given what we have?

    Does it make the most sense to buy 3 PWM controllers to run 3 separate sets as Coot outlines?

    Thanks tons. Kiva wishes she could send y'all elk jerky and woodstove-baked cookies.

    Jesse
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Jesse,

    The 14 hours a day of a 10 amp steady state load was based on average solar power available from the sun (some days more, some days less).

    It sounds like your solar panels and charge controller are working correctly--so that part is OK.

    And, an MPPT controller, in your case, may increase your solar panel output a bit (~10-20%)--however, that will only be in cold weather--not during the hot summer months. At this point, I personally do not see a need for a MPPT controller unless one of your other ones fails.

    And you have no need for additional PWM controllers to split the array. Will not make any difference (that I can see).

    As to how long will your batteries supply your 10 amp load:

    AGM: 7x 85 AH at 12 volts = 595 AH
    Trojan: 8x 225 amp hour at 6 volts * 0.5 for 12 volt hank = 900 AH
    ==================================================
    Total 1,495 AH at 12 volt

    Assuming you don't discharge below 50% (longer battery life, and never discharge below 20% state of charge or you can damage your bank):
    • 1,495 AH * 0.50 max discharge * 1/10 amp load = 74.75 hours or 3 days
    So, yes yo have a lot of battery capacity--and if the batteries are fully charged, 3 days of a 10 amp load should not be a problem.

    The max charging rate of your solar panels is around 31 amps:
    • 31 amps / 1,495 AH = 0.02 or 2% charge:battery capacity ratio
    That is a very low charge rate... Normally we recommend a range of 5%-13% charge rate... So, from our point of view, you have either way too little solar panels or way too much battery bank for your current solar array.

    The wild cards in this are the mixture of battery chemistry and the large battery bank with relatively small amounts of solar power.

    The mixed chemistry may mean that one type of battery is getting fully charged, and the other type is not.

    The way large battery bank, especially with flooded cell batteries--As they age, their self discharge rates go up (1% per day) and can, in your case consume your entire solar array's output just to try and keep them charged.

    What should you do??? Depends on how much money you have to spend and what other equipment you have available.

    My suggestion would be to split the bank to AGM vs Flooded Cell. And get a good quality AC battery charger and genset--and recharge them to 100% state of charge (basically 14.x volts and little charging current). You could use the genset for flooded cell bank, and the solar panels for the AGM bank.

    Then, place your load on each bank, and see how long you can run your 10 amp load one each bank:
    • 900 AH * 0.50 discharge * 1/10 amps - 45 hours of load (pass)
    • 595 AH * 0.50 discharge * 1/10 amps = 30 hours of load (pass)
    You may find that the batteries are fine, or that one or more are near end of life.

    At this point, your array is sized nicely to power your AGM battery bank. The Flooded Cell are just too large without using a genset to keep them up (my guess).

    I guess my question is are you happy with your system--Or are you running out of power at night (what is the bank voltage at the end of the night). I am guessing you are running out of power with the blinking yellow light--so that means that your batteries are not getting fully charged, your loads are more than you think, or the batteries are aging and not able to supply as much energy as the used to.

    And, if as Marc is guessing, you are chronically undercharging/over-discharging/"deficit-charging" your battery bank--then the batteries will fail sooner (3-4 years of life vs 6-8 years of life).

    To help you with understanding your electrical use: Think of your solar charging system like a gas pump pumping XX gallons of gas per day... And the batteries are a fuel tank with XXX gallons of capacity (and some gas evaporate/leaks/etc. from the tank--the larger/older the tank, the more it "leaks").

    Watts and Amps are like Gallons per hour, a rate. How fast you are recharging or discharging your battery bank, how much power your devices are using.

    Watt*Hours and Amp*Hours are the gallons themselves (a value). How many gallons are in the tank, how many gallons did your devices use in the last day, etc.

    You will see us switch between Amp and Watts, and Amp*Hours and Watt*Hours.

    Traditionally, the "battery guys" used Amps and Amp*Hours.

    The engineers and electrical power industry typically used Watts and Watt*Hours (and kWH for home power billing, etc.).

    Both are good and have their place... But it probably will confuse you to no end... Basically Amps and Amp*Hours is just missing the operating voltage (12 volts for your battery bank. 120 volts for your AC loads).

    So to convert back and forth--just multiply or divide by the voltage you are talking about:
    • Watt = Amps * Volts
    • Watt*Hours = Amps * Hours * Volts
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Anima Center
    Anima Center Registered Users Posts: 16
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Item 1: This is a wildlife refuge and retreat center, so gas powered generator nor a regular option. Possibly could borrow one and charger to do an equalizing charge as you suggest.

    Item 2: Still doesn't make sense we are undercharging, when it is blinking green and 14v all afternoon in the sun, doesn't the blinking mean the bank is 80% or better charged?

    Item 3: We are running out of power long before 3 days, using all 15 batteries. Can detach the wet cell batteries I suppose, but then we'd have only have the storage capacity?

    Item 4: Is there a way to charge both sets of batteries if we separate them, besides separate panels and controller (or generator)?

    Item 5: We tested each battery separately with an automotive tester that puts a load on them, and they checked out. Wondered if the controller was confused, but the batteries show 12.7 when tested unhooked. Should I still wonder about them?

    Item 6: What is the best configuration, if we were to break the panels into strings before running them serial for 48V?

    Item 7: We hare running them into the controller at 12v now, that's not as efficient, right?

    Item 8: How many more watts of solar panels would we need to buy to be balanced with the 15 battery bank, if we were to keep them connected together?

    Don't know whether to split up batteries, run two different separate systems for each type of battery, or just add more panels, put the older panels in recommended strings, and buy a larger controller to accommodate...

    Ever more grateful,
    Jesse and Kiva
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    The AGMs probably don't need an equalization charge and many recommend not EQing at all, but the T-105s definitely should get equalized. They are two years old - have they ever been EQ'd?

    If you put water in the T-105s, you are using only distilled water yes?

    As B.B. said, I would split the banks and charge them separately and see how they perform. I would bet that the T-105s are the ones that are dropping voltage faster.

    You could start with just a simple battery bank switch (NAWS sells them) and switch back and forth. Since you have enough battery to last for days, then it won't be a big deal to run off one or the other for a while (while recharging that one bank every day via solar) and then switch to the other and compare performance. I'd probably switch on a weekly basis to see how they compare.

    I think Bill is right through, you need to beg, borrow or steal a small generator and a big charger (big as in up in the 60a-100a range) and top those batteries off. You need to use a charger that can EQ, not for the AGMs (unless the specs recommend EQing), but those T-105s almost certainly need it (EQ is supposed to be like a once a month item on the maintenance checklist).
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    You cannot have flooded and AGM batteries charged from same source together. The T-105s need higher voltage to be fully charged, than AGM Sunextenders. Floodies usually take 14.7 - 14.9 V to charge, while AGMs should not be taken beyond 14.4 - 14.6 V after which they will just gas the electrolyte away and die.

    Your T-105s probably need to be equalized. Disconnect AGMs and set controller voltage to 15.5V. Follow the usual battery equalizing procedures. Don't forget to disconnect AGMs while equalizing T-105s or you will destroy them.

    If your solar system cannot generate enough power to raise T-105's voltage to 15.5V, then split them in groups and equalize them one at a time.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    if you are mixing agms and flas, be it charging or discharging, this is not recommended at all as they have characteristics that are different enough that they should not be mixed. agms will be sensitive to overcharging if the voltage is too high like fla types need to reach full charge and agms have a higher at rest voltage than flas.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Hmmm. Separate the FLA's and AGM's. Yes. Then you'll need a couple different charge sources, like dividing up the panels into different arrays, with separate controllers programmed for the two different battery types.

    Don't mind me. I've been driving all day and need a nap. :blush:
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Not having a backup generator is a major handicap. Even though you are remote, wilderness site, a honda EU series, properly installed can be made VERY quiet. Run times can be minimized, and timed to maximize charging and minimize noise.

    Tony
  • Anima Center
    Anima Center Registered Users Posts: 16
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Thanks, Coot, Dave and everyone. Still have some numbered questions, if anyone can answer them for us:

    1. Still doesn't make sense we are undercharging, when it the controller is blinking green and 14v all afternoon in the sun, doesn't the blinking mean the bank is 80% or better charged?

    2. We tested each battery separately with an automotive tester that puts a load on them, and they checked out. Wondered if the controller was confused, but the batteries show 12.7 when tested unhooked. Should I still wonder about them?

    3. Is there a way to charge 2 sets of batteries if we separate the 7 AGM Gel from the 8 flooded Trojans, besides a separate array and controller (or generator)?

    3. If we run only the AGMs from the existing panels, and then buy another controller and panels for the flooded bank, is there a way for us to easily switch from one bank to the other as one runs low?

    4. What is the best configuration of my panels listed, if we were to break the panels into strings before running them serial for 48V?

    Rack 1
    1 Astropower: 75W–17.0V–21V OCV–4.4A
    1 Evergreen: 120W–17.6V–21.5 OCV–6.82
    1 Kyocera: 120W–16.9V–21.5 OCV–7.10A
    Rack 2
    3 Pacific Panels,Each:20W–16.05V–22.6 OCV–1.25A
    1 Solarex Unmarked 20-35W?
    Rack 3
    2 Shell Panels, each: 85W–17.2V–22.2 OCV–4.95A

    Thanks ever so much, couldn't deal with this without you.
    Jesse and Kiva
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    Thanks, Coot, Dave and everyone. Still have some numbered questions, if anyone can answer them for us:

    1. Still doesn't make sense we are undercharging, when it the controller is blinking green and 14v all afternoon in the sun, doesn't the blinking mean the bank is 80% or better charged?

    This is because of not getting sufficient charge current to keep the FLA's sulphation levels down and electrolyte mixed. The effective result is that the batteries' functional capacity diminishes over time, so a 225 Amp/hr battery becomes a 100 Amp/hr battery then a 50 Amp/hr battery and eventually a zero Amp/hr battery. Like the difference between a 'AAA' cell and a 'D' cell: both read 1.65 Volts but have significantly different capacity for providing power over time.
    2. We tested each battery separately with an automotive tester that puts a load on them, and they checked out. Wondered if the controller was confused, but the batteries show 12.7 when tested unhooked. Should I still wonder about them?
    The only really good way to check an FLA is with a hydrometer. Automotive load tester ... questionable results. Remember you can have the right Voltage reading but not have as much capacity left. Even with 'load' testing, as most auto batteries are only about 100 Amp/hrs. I would be leery of this test for that reason.
    3. Is there a way to charge 2 sets of batteries if we separate the 7 AGM Gel from the 8 flooded Trojans, besides a separate array and controller (or generator)?
    Not any very practical way, as you'd have to switch battery types and reprogram the charge controller every time you wanted to change banks. (Note: AGM's are not Gel batteries. Which have you got? It's already confused me once into thinking you had 3 types and needed 3 charge controllers! :blush:)
    3. If we run only the AGMs from the existing panels, and then buy another controller and panels for the flooded bank, is there a way for us to easily switch from one bank to the other as one runs low?
    Yes! The battery switch: http://store.solar-electric.com/basw1300amp.html
    4. What is the best configuration of my panels listed, if we were to break the panels into strings before running them serial for 48V?

    Rack 1
    1 Astropower: 75W–17.0V–21V OCV–4.4A
    1 Evergreen: 120W–17.6V–21.5 OCV–6.82
    1 Kyocera: 120W–16.9V–21.5 OCV–7.10A
    Rack 2
    3 Pacific Panels,Each:20W–16.05V–22.6 OCV–1.25A
    1 Solarex Unmarked 20-35W?
    Rack 3
    2 Shell Panels, each: 85W–17.2V–22.2 OCV–4.95A

    Well I already rendered my opinion on that once and was disagreed with so ... :blush:
    Thanks ever so much, couldn't deal with this without you.
    Jesse and Kiva
    You're welcome, and hopefully not too confused.
    If people didn't ask us questions we wouldn't have any use for the answers!:p
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Well, the Morningstar SunSaver Duo PWM charge controller is made to charge two batteries (or banks).

    http://store.solar-electric.com/modubachco25.html

    It has a dip switch setting for each bank type, so each can be set to either sealed or flooded.

    The voltage set points are pre-configured for sealed and flooded.

    Both settings float at 13.7, sealed absorbs at 14.1 and flooded absorbs at 14.4. Also, for the flooded setting it will do a "boost" (EQ) at 14.8v for 2 hours every 28 days (doesn't do that when set to sealed).

    It also has a dip switch setting for priority, either 90/10 where battery 1 gets 90% of the charge current and battery 2 gets 10%, until battery 1 gets full then more goes to battery 2. The other setting is 50/50.

    Apparently there is also a computer interface that you can buy that will let you fine tune it even more.

    http://www.morningstarcorp.com/en/support/library/SunSaver%20Duo%20Manual.pdf

    The problem is of course, that the Duo is only a 25a charger, which would probably be close to perfect with the panels they have now, but won't be enough with more panels later.

    But they can use two Duos, so I would say buy one now and use the panels you have, then later add another Duo and more panels. (The multiple chargers won't butt heads, they'll work fine together.)
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    i think you need to run 2 separate systems. you also have 31a from a 30a controller with a possible 32a from the pvs so you are limited right there by the controller. this leads us to the problem of undercharging which is quite possible given your crazy mix of pvs and batteries and even if they were the same i would still recommend more pvs. the higher power will necessitate another controller without any doubt. i would also steer away from making the pvs a series arrangement as this mandates an mppt controller and even that would not be optimally fed by a mixed bag of pvs.
    you should note that agm batteries have a higher at rest voltage than fla types and this will keep the fla types charged by discharging the agms slightly. never should different types of batteries be mixed and even batteries whose age or capacity are different is not good either. now we can't say for sure the condition of your batteries at this point, but my guess is diminished capacity and hence premature lighting of the all charged idiot light. (no i'm not calling you a name, but referencing to what the light actually is as it does not show capacity and only shows it most likely won't take any more charge.) you should also know that agms are more efficient batteries than fla types. as such they may take a bigger brunt of the charging/discharging cycle and will degrade these batteries faster than normal.
    as to the present pvs you have i see no problem paralleling pv array 1 and pv array 3. pv array 2 is a bit of a problem being much lower in the vmp area and it is unknown if blocking diodes are in place or not either as differentials between pvs when all paralleled will discharge a bit of the power from 1 pv to another. note we aren't talking about even reaching the controller as that controller will stop a backflow of current from the batteries and won't stop interaction between pvs. these all need fused too btw.
    if you keep the drain of power down sufficiently you may get away with less than 5% charge rates to the batteries and it's moreso true for the agms. under no circumstance do i recommend under 3% and it will in all likelyhood be around 4% for the agms and 5% for the flas with no loads on them when charging.
    in general you will probably need to up your pv wattage with possibly the low vmp pvs handled separately or not at all. add to that the additional controller and possibly a battery switch to switch the battery banks, but that may be eliminated if the loads are also separated so that maybe the lights and stereo only for example are only on 1 system and the rest on the other. this needs to be figured for capacity and loads as to how the best arrangement may be.
    all bets are off if the capacity of the batteries has been compromised as nobody then knows for sure how long they will last and at what capacity. sunxtenders do have a specific procedure for load testing, but the trouble with that is if you are already somewhat compromised on your capacity that the test itself could further compromise them.
  • Anima Center
    Anima Center Registered Users Posts: 16
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    So, tell me if I have it right please.

    I either need to sell the Trojans, or run 2 separate systems.

    Trojans will require a gen for equalizing, if I keep them. The AGMs may not require a gen.

    There is no dual bank controller larger than 25amps.

    I have enough panels already for the 7 AGMs, but need more wattage if I have more storage.

    If I keep the Trojans for a separate system, I need about 30 amps of panels to keep it properly charged.

    If I use 2 systems, I either use the Blue Sea switch or dedicate different loads to each.

    The low watt panels should be pulled out of the systems regardless.

    I don't need to make strings of matched panels, or jump up to 24volt (there is only 30 feet of wire between the arrays and the batteries).

    I should never have the weaker panels between the strong ones and the controller.

    Is that all correct so far?

    If so, which is more practical: Buying 30 amps worth of panels, a controller, wire, switch etc for the Trojans, and maybe another panel for the AGMs.... or else, trying to sell the Trojans and stick with one system, with more AGMs, more panels and a 45 or 60 amp (non MTTP) controller??

    Might actually be able to figure out what to try and buy now, mercy!

    Best,
    Jess
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    I either need to sell the Trojans...

    Yes, I has this on my mind the whole time. Makes no sense to buy more solar to keep old and inefficient battery tech happy. Sell those T-105s, or at least go without them to see how your system will work.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    I'll just suggest you re-evaluate your system based on what you determine your daily load requirements to be. Without knowing how much power you need to supply it's pretty hard to figure out the best way to supply it.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    I either need to sell the Trojans, or run 2 separate systems.
    As Marc says above--we still don't know/understand your daily load... The initial calculations seem to indicate that you are right on the edge of more load than the solar panels can reliably output for you (if you get a cloudy/hazy stretch of weather especially).

    You may want/need the larger battery bank if you get more solar panels--but mixing the AGM+Flooded cell on one bank is not a great idea. Using the A/B switch may sort of help--especially if you get additional power sources (genset or more solar panels).
    Trojans will require a gen for equalizing, if I keep them. The AGMs may not require a gen.

    Or more solar panels... Regarding the genset--Your needs may decide if you need one (especially for days/week of bad weather) or not.

    Most of a solar off-grid system is pretty bullet proof... However, the batteries are the one thing that will die early if treated badly.

    Having a small(er) genset with 10-20 gallons of fuel (and fuel stabilizer for up to ~1 year storage if kept reasonably cool) is usually good insurance and pretty handy at times too.
    There is no dual bank controller larger than 25amps.

    Most PWM controllers (not MPPT) can actually share a solar array... You could increase the size of your solar array and use one controller to charge your AGM bank and a second controller to charge your flooded cell bank. The two banks (and controllers) would share a common negative ground connection between them.
    I have enough panels already for the 7 AGMs, but need more wattage if I have more storage.

    More or less correct... The other big issue is your daily load requirements (Amps times Hours). I really recommend some mix of one or more of the following:
    Each tool has its place. A Battery Monitor (especially with AGM's) is a really nice tool to have since you cannot measure specific gravity.
    If I keep the Trojans for a separate system, I need about 30 amps of panels to keep it properly charged.

    To charge and use them... If you are just keeping them in "storage"--You could get by with 1/2 that amount of solar panels or less and just charge/equalize them once every month or so (as needed).

    If you where going to be "using the bank"--yes, I would go 45 amp minimum of solar panels (45a*17.5v=~800 watts of solar panels)--the 5%-13% of rated capacity rule of thumb.
    If I use 2 systems, I either use the Blue Sea switch or dedicate different loads to each.

    It is difficult to know what would be good for your installation. I am not an advocate of manual switching of battery banks... I assume that it will get old and eventually people will stop doing it.
    The low watt panels should be pulled out of the systems regardless.

    No, as you have them wired right now--they are not hurting anything and (hopefully) are contributing to your energy production.
    I don't need to make strings of matched panels, or jump up to 24volt (there is only 30 feet of wire between the arrays and the batteries).
    I should never have the weaker panels between the strong ones and the controller.

    Not a clear way of stating the problem/solution... Basically, for parallel connections, the Vmp's should be close (within 10% for MPPT controllers, > 15 volts for PWM controllers on a 12 volt battery bank). If you have a Vmp=17 volt and Vmp=34 volt on one controller in parallel--it is, at the very least, a waste of 1/2 the energy of the Vmp=34 volt panel.

    For series connections (you are not doing any at this time)--you would not put a 12 volt car battery and motorcycle battery in series for 24 volts--The smaller battery will get damaged/destroyed if there is a heavy or sustained load (car battery >>> motorcycle battery).

    However, you could put a 12 volt car battery in parallel with a 12 volt motorcycle battery and it will work (not great or recommended, but it will work--just like your system is working so far with AGM+Flooded cell in parallel).

    At this point, your system is still "small"--so unless you need 24 volts for something--I would wait and define your needs first.

    Regarding the 30 feet from solar panels to charge controller--what gauge wire are you running? Too small of wire and long distances will give you lots of voltage drop--and 12 volt systems (especially) do not tolerate voltage drops very well.
    If so, which is more practical: Buying 30 amps worth of panels, a controller, wire, switch etc for the Trojans, and maybe another panel for the AGMs.... or else, trying to sell the Trojans and stick with one system, with more AGMs, more panels and a 45 or 60 amp (non MTTP) controller??

    In general, define/measure your loads first (amps/watts and time/hours)--then define/build your system.

    It is very difficult for us to guess at what is optimum for you without knowing your loads.

    And, as you can see, it is possible to put a system together out of bits and pieces--but it becomes very difficult to service/understand/get good life out of the batteries.

    In the end, it sounds like the system is sort of meeting your needs right now--but the batteries are either not getting charged (not enough solar panels + too much loading + no backup generator/charger).

    Measuring your daily load (amp*hours of DC use) would be a good start. Just connecting to your AGM bank for now, possibly another good thing to do (assuming the AGM's are still good--Not known at this time).

    Getting a full charge on all of your batteries (generator, put 1/2 your bank on an outbound truck for charging at home/office) and then seeing how the hold up with a known load--will tell you a lot.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Anima Center
    Anima Center Registered Users Posts: 16
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School

    Thanks, makes more sense all the time.

    I mentioned our load early on, at least as measured by the controller which shows us using a very steady 9 to 10 amps of power at 12v, from 7am til 11pm, 16 hrs per day. We use no AC except the satellite internet box, run through a small 150watt inverter that is turned off at night. The only other significant draw is our two dual processor mac laptops. Does this mean 160 amp hrs of use a day, or is my math wrong?

    Would like to be able to run the above for 3 days of clouds, rare as that is.

    Does this help affect your advice?

    Plan is to remove the Trojans for now at least, wondering if I should get a larger controller and another panel, and if I should run the panels from lowest output to highest and then to controller?

    Jess
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    There is no dual bank controller larger than 25amps.

    I'm sure there probably are some, but I can't recall any off the top of my head. I used the SS Duo in my example because A) it can handle having different types of batteries on each output (and only EQ the flooded not the AGM), B) it's about the right size for the PV you have now, C) it's not expensive and D) it's PWM, not MPPT so it's better able to handle that hodgepodge of PV panels.

    By using one of the Duos now you can go ahead and split the banks and use what you've got to charge them and EQ the flooded bank. Later, you can add another Duo and some more PV panels to increase the charging capacity.

    You still need to split the banks, but you can connect the loads to the switch that Coot talked about, and switch back and forth between which banks are supplying the loads.

    That's about the quickest, cheapest "fix" I could come up with using what you've already got.

    And yes, until you get some more PV you need to use a gen and a big charger to make sure those batteries are getting topped up enough to keep them healthy. Though...after a few years of chronic undercharge they may not be so healthy now...

    And that is true even if you dump the FLAs and keep the AGMs - you will probably still need to use a gen to get those AGMs topped up and keep them there.

    Or, you could spend more money and certainly do it better.

    Dumping the FLAs and getting more AGMs is probably not the way to go at this point, since mixing older and newer batteries (even of the same type) is usually not a great idea.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Mixed Panels and Controller Confusion: Advice Needed for Wilderness School
    Thanks, makes more sense all the time.

    I mentioned our load early on, at least as measured by the controller which shows us using a very steady 9 to 10 amps of power at 12v, from 7am til 11pm, 16 hrs per day. We use no AC except the satellite internet box, run through a small 150watt inverter that is turned off at night. The only other significant draw is our two dual processor mac laptops. Does this mean 160 amp hrs of use a day, or is my math wrong?

    You're basically correct: 10 Amps over 16 hours is 160 Amp/hrs. But to supply that you need at least 2X the capacity in batteries because you don't want to take them below 50% Depth Of Discharge. So a minimum battery size would be 320 Amp/hrs, which is not at all unusual for a 12 V system. But this doesn't include your occasional AC usage, which could be 40-50 Watts (based on my own set-up, yours could be different) depending on how much the inverter itself uses. That's another 4-5 Amps per hour.
    Would like to be able to run the above for 3 days of clouds, rare as that is.

    That's where this stuff gets expensive; surplus off-grid capacity. You're always kicking yourself for not be able to make use of the full harvest potential on sunny days! A good solution here would be to set up for 25% DOD on the bank daily under ordinary circumstances, thus giving you one day's reserve capacity by taking the bank down to 50% if needs be. So there you'd have 640 Amp/hrs. To charge that you'd need approximately 850 Watts of panel, maybe a little less (I based that on typical panel efficiency and a 7.5% charge rate to be in the middle*). Any way you slice it, you're short on panel. Especially if you want "no generator" reserve capacity.
    Does this help affect your advice?

    Plan is to remove the Trojans for now at least, wondering if I should get a larger controller and another panel, and if I should run the panels from lowest output to highest and then to controller?

    Jess

    See what you can do about charging each and every battery. Let them sit for a day. Test each FLA with a hydrometer and see how it reads. Check the AGM's for Voltage. Try to find which are your best batteries of each set.

    * 640 Amp/hrs @ 7.5% = 48 Amps, which your existing controller can't manage. 48 Amps @ 14.2 Volts = 681.6 Watts @ 80% = 852 Watts total.
    320 Amp/hrs @ 7.5% = 24 Amps, which your controller will handle. In fact, at 30 Amps it would be ideal for that much battery. 30 Amps @ 14.2 Volts = 426 Watts @ 80% = 532 Watts total. So your existing panels and controller should be suitable for 320 Amp/hrs or there about if you have a battery configuration that can come close to that. This would meet your minimum needs, just barely.

    Does that help or is it more confusing?