Solar panels and controllers

edwingedwing Registered Users Posts: 4
edited November 12 in Solar Beginners Corner #1
I am a beginner on this, I bought three 260W solar panels, a PWM charge controller 12/24 50A and a 5000watt 12v inverter that is going to be with 4 12 volt batteries.

We installed the panels and found out that they are 37volt panels and I can not return them back. Here in Puerto Rico with Hurricane Maria hit us hard and power is down.

I need you help and expertise to fix or alter this problem. I see in the internet that it won't work. Any help is welcome.

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    I would think we are trying to find the least costly way to effectively use they panels?

    What is the VOC and VMP of the panels? or what is the actual panel name Like "Trina Solar TSM-260" or you can count all the cells on the panel, there should be either 60 or 72.

    Nothing will be simple, The panels are likely 60 cell panels, good news it you could use the inverter you have, but will need a MPPT type charge controller, not inexpensive. If they are 72 cell panels, you could configure your batteries in a 24 volt system (2 parallel strings of 2) and buy a 24 volt inverter, a better option in my opinion. The 5000 watt inverter is larger than you want to use on 12 volts and larger than you would normally try to run on a system with 780 watts of array.

    I'm hoping you have 72 cell panels, it would make for a better system.

    If you have 60 cell panels, which I suspect. You should look for a MPPT type inverter with 60 or more amps of output.

    Something like The Midnite Classic SL
    https://www.solar-electric.com/midnite-solar-classic-150-sl-charge-controller.html
    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.
  • EstragonEstragon Registered Users Posts: 1,545 ✭✭✭✭
    You might be able to use the panels, although not at full potential. An mppt controller can use the full available wattage from the panel by stepping down the voltage and increasing charging current. Your pwm controller will just pass through current. Best option would be to get an mppt controller. Pwm tend to be relatively inexpensive, so likely not a huge loss and you may be able to use it when you add more panels.

    One possible, but not great solution, would be to charge the batteries as a 24v bank, and change wiring to 12v to run the inverter. This would require some thought on how to switch safely. The inverter couldn't be connected while charging.

    You could tap 12v off a 24v bank, but this will likely lead to premature battery problems.

    A 5000w 12v inverter is some pretty big current. You will need some really heavy cable and proper breakers/fusing. What are your likely loads? 4 12v batteries won't run anything like 5kw for very long. If you really need that kind of power for long, you may need that extra controller.
    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
  • BB.BB. Super Moderators Posts: 26,837 admin
    What are three amp×hour rating of your 12 volt batteries?

    What loads do you want to run?

    Typically, with a balanced system design of loads define battery bank => defines solar array+ac inverter.

    Roughly, for a useful system, the a.c. inverter should not be any larger than the solar array (5,000 watt inverter will use up a day's solar harvest in a 1/2 hour or so).

    For your existing system, a 250-500 watt inverter makes more sense. (Just guessing at the moment, need more details from you).

    - Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivormcgivor Registered Users Posts: 1,280 ✭✭✭✭
    edited November 12 #5
    As you already have the panels, charge controller, batteries which can be configured 24V nominal, the outstanding device which wouldn't work is the inverter, which is, as pointed out simply too large. Although not ideal the panels can work at 24V as long as ambient temperatures are not extreme, around 32°C or less seems to be fine if the Vmp is >30V, the only problem is equalization is not possible, based on experience with similar panels PWM in the tropics.

    My suggestion would be to parallel the panels, series parallel the batteries to 24V to see if it will charge, especially during the hottest part of the day around noon with direct overhead sun, basically if there is current flow it's working. As an experiment, if the controller allows equalization, not all do, activate an EQ, again hottest period, and observe the maximum voltage the panels can output. If the voltage is around 30V it should work (the basic charging not EQ) again, this is NOT an ideal arrangement, but may get you going, at very least it will get some charge into the now self dischargeing batteries. 

    The inverter could be replaced with something more suitable for the array ( don't know battery capacity) with something like this http://www.samlexamerica.com/products/ProductDetail.aspx?pid=500 just remember with a small system there are limitations, it can't power a house like the grid can, consider it an emergency minimalist setup, lights, phone chargers, perhaps a fan, loads must not exceed battery and or PV capacity, more details would help others with suggestions and guidance. 

    The best solution however would be a MPPT controller, I'm not trying to take away from the good advice already given, just an option until such time a MPPT is aquired.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • edwingedwing Registered Users Posts: 4
    Photowhit said:
    I would think we are trying to find the least costly way to effectively use they panels?

    What is the VOC and VMP of the panels? or what is the actual panel name Like "Trina Solar TSM-260" or you can count all the cells on the panel, there should be either 60 or 72.

    Nothing will be simple, The panels are likely 60 cell panels, good news it you could use the inverter you have, but will need a MPPT type charge controller, not inexpensive. If they are 72 cell panels, you could configure your batteries in a 24 volt system (2 parallel strings of 2) and buy a 24 volt inverter, a better option in my opinion. The 5000 watt inverter is larger than you want to use on 12 volts and larger than you would normally try to run on a system with 780 watts of array.

    I'm hoping you have 72 cell panels, it would make for a better system.

    If you have 60 cell panels, which I suspect. You should look for a MPPT type inverter with 60 or more amps of output.

    Something like The Midnite Classic SL
    https://www.solar-electric.com/midnite-solar-classic-150-sl-charge-controllerT
    The solar panels are Recon model RCM-260-6MB and have 60 cels
    Max Power voltage-31.70 volts
    Max Power current-8.32 amps
    Open circuit voltage-38.52 volts
    Short circuit current-8.66 amps
    Max series fuse-15A
    Max system voltage-1000 VDC
    Field wiring- 12AWG

  • edwingedwing Registered Users Posts: 4
    This project is only for emergency and the biggest appliance in my house is the refrigerator 
    and that's all.
  • westbranchwestbranch Solar Expert Posts: 4,860 ✭✭✭✭
    how old is the fridge? does it have an EPA avg. yearly power consumption value?  if old you may need a > 2500w inverter, mine is 3 years old GE and rated at 319kWh/yr and runs easily on a solid 1500W Cotek inverter. thje system runs the whole house ( fridge , lights, and power tools and chargers) easily with only 1120W incoming and keeps the battery fully charged, see my signature below.
     
    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, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    Thank you for the reply, The inverter is pretty much over kill for the size battery bank and the intended uses. 

    I/we don't like to see that many batteries in parallel, it invites uneven usage. Be sure to wire them as evenly as possible so each battery has equal wiring resistance through the system. 

    As I stated earlier, you will need a MPPT type charge controller for your solar panels. Since 3 260 watt solar panels, 780 watt array, should generate about 780 x 75% or about 585 watts. You will need a MPPT type charge controller that will handle 585/12volts = 487.5 amps

    You could sneak it all on a Morningstar MPPT TS-45, slightly more output than this can normally handle, but you can over panel it without worry.(about $480)

    https://www.solar-electric.com/motr45ampmps.html

    Or put it on a Midnite Classic SL with room to grow, It will handle around 88 amps output (about $515)

    https://www.solar-electric.com/midnite-solar-classic-150-sl-charge-controller.html

    A 5000 watt inverter is likely/most probably a modified sine wave inverter. Modified sine wave inverters would be okay for emergency use, but motors (like the compressor in your refrigerator) will run hotter, shortening their life and use more energy. So long term use would not be recommended. They will also likely draw a lot of current if left on, so if you have an outage turn it on, but don't leave it running. If you never intend to run more than 1500 watts, I would wire it like that, use a 150 amp breaker and 2/0 wire to connect the inverter. To run at 5000 watts, you would need huge cable and short distances.
    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.
  • edwingedwing Registered Users Posts: 4
    how old is the fridge? does it have an EPA avg. yearly power consumption value?  if old you may need a > 2500w inverter, mine is 3 years old GE and rated at 319kWh/yr and runs easily on a solid 1500W Cotek inverter. thje system runs the whole house ( fridge , lights, and power tools and chargers) easily with only 1120W incoming and keeps the battery fully charged, see my signature below.

    Mine is a Frigidaire and it is at 407.34 kWh/yr.
  • westbranchwestbranch Solar Expert Posts: 4,860 ✭✭✭✭
    not  the lowest but good, lots much higher. Get an MPPT as suggested and go to 24 volts if possible, and a smaller inverter if you  only want to run fridge and lights. if possible can you get another panel if yhe3 PVs cannot support the draw.? 24 volt will use smaller wire and save you money.

     
    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, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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