Question regarding CC, and about auto switching circuit/ some idea for mods/admins

NilaNila Solar Expert Posts: 173 ✭✭
Hi All

Sorry for this LOOOONG post, I wanted to put them all together in one post just because I am lazy :)

I have a 2KW array 250x8 panels.. 4 strings of 2. VMP: 30.6.
I had a chinese charge controller which i am planning to replace with a Tristar PWM.

I have already posted about this setup intially
1. before I started
2. After setup
3. Overvoltage issue

I have 4 LA 200AH batteries all 12V in series to form a 48V bank.


Today I have checked my batteries with a Specific gravity . most of the cells are around 1230-1250 range.. one or two are at 1225 and handful of them above 1250/1265.
I checked the same batteries yesterday evening after the day of scorching sun with no load,etc. Most of the cells were 1265 range..

I believe the sun charging is very good, It does seem to overcharge it a bit due to CC.. like upto 60V-61V but is generally doing okay... and after the day, the cells SG is okay.

But when there is a power failure on evening and batteries go down a bit.. and gets charged after the power comes back..
My inverter's charging I believe sucks.. it overall never goes higher than 54V ( checked only with multimeter ) at all..and after it finishes chargeing , some of the cells are very low.. like 1170 range.. which shows as poor in my hydrometer.

General pattern is the farther then cell from the charging terminal.. the value is lower.. so the cell closest to the charging posts are having 1265+ SG after the Inverter's charging.

I did not specify each and every cell's SG here because I thought it would make this post even longer.. I can put it in a google doc and show here if anyone requires me to show all those readings .

Now I believe I have 2 problems,
1. Charge controller overcharging , Inverter's Undercharging my batteries..

One I can fix by using a new CC.
so Regarding the new CC. I am looking at tristar 45 PWM.

Since I am having an array that can only produce upto 60VMP, I am not sure if it will help me much with a MPPT here also I am bit concerned about the cost of nice MPPTs .
My budget is like 200-250 USD range.

I am also looking at possible expansion of this setup.. to may be upto 3KW when i make my battery bank to have 8 batteries instad of 4 now ( which should die in a year of time if i keep charging them like this ) .

Assuming I need to add 1 more KW , should i get the 60A ? , Is it possible to add like 2 more parallel lines to this setup? (if i use PWM)
so that would become 6 parallel wires going into the CC ? is this even advisable? or should i stop with this 2kw panels for now.

Or Would you rather suggest adding 1 MPPT cc and then use 3x3 setup .
reading this forum I came to know, the solar array is more more easier to design if we use MPPTs .

I would like to go with MPPT if it is the only option and the amount of losses is very high.



Regarding automating my inverter to automatically switch on/off based on the PV Input/Battery voltages,etc
I was initially looking for Timer switches,etc or read made circuits that help switching my grid based on the time/pv voltage which should work for 30A/230V and didnt find many.

Then I just made one myself with help of Arduino/Relay, I believe same can be easily used to switch on the generators,etc.
If it helps anyone I can post that circuit and code,etc . Its working nicely so far :)


Info for Admins of this forum: Just a suggestion, not sure if this is the right place to post , Mods please remove this if its not required.
Please raise the session timeout for this forum , I seem to get logged out quite so often . I have tried all my browsers/different PC's.
Usually sites like Forum does not need quick session timeouts.. as there is no CC or sensitive stuff here. You may enable cookies,etc to make this session last longer .

P.S I can help with this as I am doing this for bread and butter for like over 10 years.. PM if any assistance is required :)

Comments

  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    You said
    General pattern is the farther then cell from the charging terminal.. the value is lower.. so the cell closest to the charging posts are having 1265+ SG after the Inverter's charging.

    this is indicating , to me, that you may have a problem with the connections between batteries if the pattern is consistent.

    start by removing , cleaning each connection and try charging again by mains. this is the simplest way , then further action may be needed.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Thanks Will try it tomorrow and post the values again.

    Is it okay to measre the SG after 8 PM ? which is at-lest 4hours after the sun charging is done?

    I would love to know if someone can suggest the CC for me too in the meantime :)
    westbranch wrote: »
    You said
    General pattern is the farther then cell from the charging terminal.. the value is lower.. so the cell closest to the charging posts are having 1265+ SG after the Inverter's charging.

    this is indicating , to me, that you may have a problem with the connections between batteries if the pattern is consistent.

    start by removing , cleaning each connection and try charging again by mains. this is the simplest way , then further action may be needed.
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Regarding the posting timeout--I believe it is set to 45 minutes right now. I will ask our admin (Windsun) again about this--But I believe there were other issues when the time limit was set longer.

    If you have your "REMEMBER ME" box set, your sessions will not timeout/require a relogin (I say "logged in" forever). But that does not fix the long post dwell time.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins
    paimpozhil wrote: »
    Is it okay to measre the SG after 8 PM ? which is at-lest 4hours after the sun charging is done?

    Unlike the voltage, which to be meaningful has to be measured several resting hours after either charging or discharging, you can measure the SG at any time and it will reflect the overall state of the cell at that moment (unless you have just added makeup water without agitation or the electrolyte is badly stratified.)
    SMA SB 3000, old BP panels.
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    I tried remember me but I am never said I am logged in when i come back after few hours or next day.

    Bill, Please suggest the CC thing quickly because I have someone flying from USA to my place soon so I would ship to them.
    BB. wrote: »
    Regarding the posting timeout--I believe it is set to 45 minutes right now. I will ask our admin (Windsun) again about this--But I believe there were other issues when the time limit was set longer.

    If you have your "REMEMBER ME" box set, your sessions will not timeout/require a relogin (I say "logged in" forever). But that does not fix the long post dwell time.

    -Bill
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins
    BB. wrote: »
    Regarding the posting timeout--I believe it is set to 45 minutes right now.

    I do not have 45 minutes to spare to try it, but does hitting "Preview Post" partway through restart the timeout?.
    Another workaround is to compose your Post text in advance (using a simple text editor rather than a word processor!), then paste it in, preview its, and fix anything that did not come out right.

    Some configurations of the underlying forum software will do an Auto-Save before the posting timeout expires and let you pick up where you left off if you wish.
    SMA SB 3000, old BP panels.
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    The forum uses cookies to track login time/login forever option.

    Make sure you have cookies enabled for this forum (and not set to delete cookies after the session is over).

    Timeout during posting--It gives me the time out error, and I can just copy to the paste buffer. For me, have to refresh the thread and hit New Post to create a new blank post, then past the buffer. (If I do not do the refresh, I cannot fix the posting timeout).

    I have asked our admin if the timer can be set longer than 45 minutes--A few years ago I asked, and the longer timeout caused grief with the forum software (process errors in background--possibly around "too many users currently logged in" or something similar).

    I am not the best person to answer the best charge controller question... From what I have seen:
    1. Midnite Classics. Reliable and most "Internet Aware". I believe you can upload firmware updates much easier than most other vendors (need special dongles, open unit to replace proms, etc.). Midnite also has a -$100 version that saves the LCD display if you will have it connected to network/remote computer. Many versions (Higher input voltage, higher output current, etc.).
    2. Rogue. Very nice smaller controllers (12/24 volt at 30 amps)... But gonig through a product update. New product is scheduled for March?
    3. Outback. Has been the gold standard for years. Upgrades to firmware are "difficult" (? I think--last I heard)
    4. MorningStar. Good TS Series (MPPT and PWM controllers). Also a very good 15 amp MPPT controller. MorningStar makes good money on options (LCD, remote battery temp sensor, computer interface, etc.). The largest TS MPPT 60 Amp controller does have an native interenet option.

    Any of the above will probably meet your needs very nicely.

    I would also suggest seeing which of the above vendors can get parts in a timely and cost effective maner to your home (li.e., any local support).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Preview post does restart the timeout so I am actually using it already.

    I was more concerned about the "Remember me" not working correctly but I will double check my cookies,etc.

    I know about that workaround of using a Text editor haha..
    but normal people wont really know about this and may find it hard :) I just wanted to point out a potential flaw to the admins.


    inetdog wrote: »
    I do not have 45 minutes to spare to try it, but does hitting "Preview Post" partway through restart the timeout?.
    Another workaround is to compose your Post text in advance (using a simple text editor rather than a word processor!), then paste it in, preview its, and fix anything that did not come out right.

    Some configurations of the underlying forum software will do an Auto-Save before the posting timeout expires and let you pick up where you left off if you wish.
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Autosave only "saves" about 1/3rd the time for me on Firefox--Don't know why.

    For long posts, I still try to copy to the paste buffer before posting/refreshing--Just in case.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins
    BB. wrote: »
    The forum uses cookies to track login time/login forever option.

    Make sure you have cookies enabled for this forum (and not set to delete cookies after the session is over).

    Timeout during posting--It gives me the time out error, and I can just copy to the paste buffer. For me, have to refresh the thread and hit New Post to create a new blank post, then past the buffer. (If I do not do the refresh, I cannot fix the posting timeout).

    I have asked our admin if the timer can be set longer than 45 minutes--A few years ago I asked, and the longer timeout caused grief with the forum software (process errors in background--possibly around "too many users currently logged in" or something similar).

    I am not the best person to answer the best charge controller question... From what I have seen:
    1. Midnite Classics. Reliable and most "Internet Aware". I believe you can upload firmware updates much easier than most other vendors (need special dongles, open unit to replace proms, etc.). Midnite also has a -$100 version that saves the LCD display if you will have it connected to network/remote computer. Many versions (Higher input voltage, higher output current, etc.).
    2. Rogue. Very nice smaller controllers (12/24 volt at 30 amps)... But gonig through a product update. New product is scheduled for March?
    3. Outback. Has been the gold standard for years. Upgrades to firmware are "difficult" (? I think--last I heard)
    4. MorningStar. Good TS Series (MPPT and PWM controllers). Also a very good 15 amp MPPT controller. MorningStar makes good money on options (LCD, remote battery temp sensor, computer interface, etc.). The largest TS MPPT 60 Amp controller does have an native interenet option.

    Any of the above will probably meet your needs very nicely.

    I would also suggest seeing which of the above vendors can get parts in a timely and cost effective maner to your home (li.e., any local support).

    -Bill

    Hi Bill,

    Thanks for suggesting the options

    Not sure if you have read through my whole post..

    I wanted idea to know if a MPPT will be much more efficient than PWM in my case?

    I seem to be getting 61v voltage for a 48v battery bank already.. not sure if MPPT can help a lot here as there is not a lot of extra voltages to downconvert to amperes,.

    I have a small partial shading though during the late evenings.. again not sure if MPPT helps with this.

    and question about 45A/60A variations of charge controllers to know if 60A is good enough to add another 1KW of panels with 2 extra strings.


    Regards to the options like LCD Screen/ Remote /etc I dont think are needed..
    Actually I can make them myself for reading the voltages/amperes/etc with arduino and set of sensors and some code

    I am going to have someone pick it up and deliver to me from USA.
    Xantrex has some support here but pricing is very high.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    IMO the Classic family (150,200,250) would be best for your large array, you may be able to reconfigure it to be slightly more efficient using higher voltages, which gives less line loss.

    I am partial to the versatility and support that Midnight gives, As you can see I have the (MX60) predecessor to the Classic and a Classic 150 which I am in the process of updating for installation in about a week. The CL150 is so much of an improvement! and I thought the MX was capable of more than I needed...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Just checking the array specs.
    Eight 250 Watt panels with Vmp 30.6 and Imp 8?
    Configured as four parallel strings of two in series giving an array Vmp of 61.2 and Imp of 32?

    You haven't really got any extra Voltage at all, just as you say. Therefor the MPPT isn't going to gain you anything. That's kind of a low Vmp for a 48 Volt system; it is barely above charging Voltage. When hot the panel output is going to drop, and you may not achieve full charge.

    Yes, a 60 Amp controller could handle another 1kW of array (think: 60 * 48 = 2880 so with the typical losses it would work MPPT or PWM). As westbranch said you might want to do something like add one more panel per string to bring the array Vmp up and use an MPPT to maximize it.

    BTW, sometimes I get "signed out" whether I'm posting are not and in well under the 45 minute time limit. I'm not sure it's the forum software alone that does this.
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    HI Mate,


    Thank you for the answer. Yeah i believe its low for my spec but my generally hot weather and for my specific set of batteries this already seems to be more than enough

    You are right about the current VMP/IMP.

    Tomorrow evening time here I will post all my SG readings and battery voltages and you will say it does charge enough :)

    Scaling is not my immediate need my battery bank is not huge enough to support more panels.
    but wanted to have it as an option for future as i am upgrading the CC now.

    Regarding the signout stuff, Im happy to help any forum Admin here try and sort this problem out if they require advice.Just PM me.
    I've who has worked on sites that have millions of pageviews, i know this stuff inside-out just as much as i suck at the solar energy :)
    I feel this would be a some way to help this forum, as i am not really able to help anyone here otherwise and Im just asking for help all the time lol.
    Usually sys admin on yout hosting can take care of this easily if reported.










    Just checking the array specs.
    Eight 250 Watt panels with Vmp 30.6 and Imp 8?
    Configured as four parallel strings of two in series giving an array Vmp of 61.2 and Imp of 32?

    You haven't really got any extra Voltage at all, just as you say. Therefor the MPPT isn't going to gain you anything. That's kind of a low Vmp for a 48 Volt system; it is barely above charging Voltage. When hot the panel output is going to drop, and you may not achieve full charge.

    Yes, a 60 Amp controller could handle another 1kW of array (think: 60 * 48 = 2880 so with the typical losses it would work MPPT or PWM). As westbranch said you might want to do something like add one more panel per string to bring the array Vmp up and use an MPPT to maximize it.

    BTW, sometimes I get "signed out" whether I'm posting are not and in well under the 45 minute time limit. I'm not sure it's the forum software alone that does this.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    Just so you are aware of the voltage ranges you should be in while charging, if yours are FLA batteries, on average:

    a 12 V batt. needs ~14.4 volts to charge,
    24 volt batt needs ~28.8 volts
    48 volt batt. needs ~57.6
    then if an EQ is needed, which it sounds like yours may need, voltages up to ~62V may be required.
    Remember these are generic numbers, and the actual values are set by the battery manufacturer.
    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: Question regarding CC, and about auto switching circuit/ some idea for mods/admins

    That is too low of array voltage. Remember Vmp is for cold panels on a cold day (around 25C cell temperatures). In real life, the cells run much hotter because of heating by the sun.

    You need to get 72 volts or higher for a pwm or mppt controller. If your Vmp is over around 80 volts, then a mppt controller makes sense.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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