Wiring two charge controllers in parallel

Hi this is Amy from the altE Store. So, do
you ever wonder what happens if you’ve got a charge controller that is only big enough
for the solar panels you’ve got, maybe one panel and a small charge controller, or you’ve
got a whole array that’s maxed out. And you want to add more solar panels. Well, all you
need to do is wire a second charge controller in parallel in your DC load center. So I’ve
got each output of the charge controller going into my DC breaker box, or load panel. And
if I turn on just one of my charge controllers, I see that I’m getting 3.04 amps in. Alright,
I’m going to turn that off and I’m turning on my second one. And it’s a different charge
controller, so the output is just slightly different, it’s 2.78A, so if I turn both of
them on, what’s happening is each charge controller is managing independently, and it’s going
to be sending its own current into the battery. So when I turn them both on, I’m getting the
sum of the two. I’m getting 5.92 amps. Because when you wire in parallel, amps increase,
and the volts stay the same. So I’ve got my two outputs of my two charge controllers going
to the battery independently managing each battery working together. Now there are some
charge controllers that will actually even allow you to connect the two charge controllers
together and get even more advanced communication between them, but as you can see, I’m not
doing that here, and they’re still working together great, so I’m just doubling my current
by having both charge controllers on and going in parallel to the battery. I hope this was
helpful, if so, give us a like and a share, and be sure to subscribe to our altE Store
channel, so we can notify you when we’ve got more videos coming out. And don’t forget to
go to our website at altestore.com , where we’ve been making renewable doable since 1999.

67 thoughts on “Wiring two charge controllers in parallel

  1. are all buss bars the same for atteching outputs from devices to the battery bank or are some better than others? like steel, aluminum, copper, brass or stainless steel?

  2. are both solar Charge Controllers getting input from separate solar Panel??
    plus one more question, you didn't mention in the video that what type of controllers are they? both are mppt? or one is mppt and other is PWM??

  3. Awesome…great info as folks grow their systems and add more panels/controllers. Love the Midnite Solar Classic's "Follow Me" mode. Gave AltE a "shout-out" on my latest video on my Channel.

  4. Amy, I am not sure I understand why I would want to connect two solar controllers in parallel ???? There's not quite enough information in this video. Am I going to do this simply to increase the overall amps my system cam handle ?? Also, how, exactly, do I make the dual controller connections ?? Am I simply adding the additional output from my extra controller to my battery array, or do I require some kind of fancy interface box to accomplish this ???

  5. good but can I use different types of panels for example 100 w and 200 w for every charger
    second question can I use different types of charger?

  6. Amy since positive and negative lines are tied to a bus bar could I also run lines to an grid tie inverter as well? This would give me a grid tie and off grid at the same time?

  7. Dear AltE, how can we make sure that the current coming to two charge controllers are equally distributed between the two charge controllers. Isn't it possible that one charge controller take over all the current and burn out and then the remaining charge controller will take over all the current and burn out as well. Please, clarify this.

  8. Hi Amy, I have a 260 W panel and 20 A mppt controller, I have a 12v system. My batteries are about 4.5 feet away from the controller, what wire gauge should I use to connect the batteries to the controller? Thanks.

  9. Hello
    My question is: I have several panels connected to (1) a cable (positive and negative)
    I can connect more solar panels to the same cable and the end of the cable to do,
    branch before the controller and connect another controler charger?
    all panels will connect to the same cable and a branch and 2 controllers,
    I do not know if I can do this or if I put another cable for more panels (on the other controller)
    Your videos are very important for people like me who learned to do everything on youtube,
    regarding solar energy, 3 years ago that consumption the sun,
    almost became an addiction but healthy.
    Thank you.

  10. Hello Amy,
    I have try'd this with two sets of panels and two charge controllers
    these are mppt controllers.
    It seems that each mppt controller "looks" at the voltage of the batteries to go on max charge
    when one mppt charger boosts the voltage on the batteries then the second controller goes on float mode.
    it simply thinks that the batteries are full charged.
    this means that the second controller does not put out the amps that we expect.

    changing the order of connection makes the other controller go on float.
    so the first one connected does the job.

    I have solved this by charging in parallel on a series of batteries

    4x 6 volt batteries are in series to get the 24 volts system voltage
    we charge 12 volt on the first two , and 12 volts on the second two batteries

    on each charge controller are two solar panels of 270 watts in series 60 cells

    this seems to work fine

    please comment


    Cor van Houtum
    Draaistroom Nederland

  11. I have a question for you if you can help me out please.
    I have 3x270w panels connected in series on my south facing roof going to a tracer 40amp mppt charge controller, charging my 24v battery bank.

  12. I also added 3x270w panels again linked in series to the west facing roof to my pip 2424smx inverter/charge controller. Now the pip will only charge at 1amp because it thinks the batteries are fully charged when there not. Any help would be appreciated.

  13. I plan on charging a 36 v lithium batteries with three 100 watt panels facing in different directions (on a a trailer) and wired in parallel for 12v. Would I need three boost controllers for this and can three boost controllers be wired in parallel in the same way as two charge controllers?

  14. I really appreciate all your educational videos on solar. Thanks for all your efforts

  15. Thank you for Video, I have two question, When we we use two charge controllers as far as i know any off grid system have one charger controller and second how i know PSH(Peak sun hours ) or worst case (Sun Hours).

  16. Hi, great videos lady! From Brazil were i stay dont have more informations (youtube) about solar charger controller acurance and confrontation about what is informed on manual and the true test over supervision by a certificated technician. By this way i am preparing a benchmark between three "low cost" devices. Best wish and accept my apologise because my english.

  17. You might want to check your schematic… looks like your
    panels are improperly connected??? Not sure what's going to happen if you wire your panels like what is depicted in
    the schematic… I'm just saying!!!

  18. hi amy, im jun from the phlippines and i have a question.
    for example in our house, the total watts of our electric consumption at the same time is 680 watts, (13 LED bulbs, few cellphone chargers, 1 led tv, laptop, 2 elec. fan)
    my question is, my 680 watts consumption, can i used a 4 pieces of 200 watts solar panel, and 4 pieces of 200ah lead acid type of battery, together with charge controller and inverter.
    thank you in advance and i hope you can find time to answer my question.

  19. hi guys,

    pls kindly help to check my wiring
    whats wrong with my connection or anything missing?
    thank u

  20. Have a couple of questions first is there a limit to how many load controllers can be in parallel? Second is there a recommended model controller that communicates with each other? Your channel rocks…

  21. its like the pv on the schematic are crossing charge controller 1 and 2. What is the correct connection did u do mam? did u wired the panel in parallel to the charge controller#1 and the other panel is in parallel to controller#2…

  22. You've answered that nagging question that I've been asking myself and others, I am setting up a solar, first, but also adding wind and hydro in phases so I can equal or at least cover most of my daily energy needs. With any surplus going to hot water and heating in winter, my question is do I take the surplus straight from the battery bank or is there a charge controller that both communicate with each other and send excess to heating system?

  23. thank you so much for your great videos!!!

    may I ask is it ok to combine PWM and MPPT charge controllers in parallel ?

  24. Your diagram fusebox… is this for ONGRID connection to fusebox in house? Or is it for offgrid with independent fusebox? I ask because of trick issues with GROUND. I purchased a xantrex 1800w prosine inverter and I think this inverter could be short circuited if connected to the house fusebox ground. Advise please this video could be misleading if people think they can just connect their inverter to their home electrical box due to GROUND cross section… Im not sure if xantrex 1800w prosine inverter is ground wire safe. The home ground crosses with the neutral… I believe… see this video HAZARD WARNING https://www.youtube.com/watch?v=FjuzyAujdC4

  25. I have a question im not sure if you can help me or not. I want to wire 2 battery controllers to a 48v battery bank, one controller is going to be coming from my solar panels to charge the batteries, the second i want to run a golf cart battery charger which is plugged into mains/grid power into the second charge controller. I would only ever turn the golf cart charger on if the batteries dropped down quit low or on says where not enough solar is bring produced as a back up. Does/would this work?

  26. Many years ago while cleaning up a battery for my car, I tried something that had me doing it for all low voltage connections. I consider any battery connections low voltage all the way up the scale. As well as the connections coming from panels and connections to anything else. I would not do this around any live connections. Take it outside. If there is any look of corrosion on any connector, not the wire because I cut that back if it is corroded, but use some steel wool preferably the thinnest you can find however, any will do. Scrub the corrosion off then wipe it off with acetone. Acetone takes off anything on metal. The connector, the screws, lock washers and nuts. Once I did that, I never had to re-clean the same connections again. Do this in another location before taking everything to connect at the live location. Electricity does strange things with pieces of steel wool flying around or most all liquids around hot connections. Be safe.

  27. [ Panel(12v)—–Panel(12v)—–Panel(12v) ] ———–>MPPT(max 20A, and connected to battery)———->PWM(max 20A, usually inside the Inverter)——–>Battery and Load


    Panels connected in series, connected to MPPT. Output from MPPT divided into 2. One goes to a battery which provides the voltage requirement for MPPT to work. The other output goes to the same battery via a PWM charge controller (max 20 A).

    Is such a circuit possible? Will the battery charge? Will the pwm part have current through it?

    PS :
    Many inverters come with PWM. The aim is to introduce the more efficient MPPT to provide current ( especially on cloudy days), directly to inverter hence working on charge direct from panels (rather than drawing it from battery and inverting it, thus minimising battery cycling)

  28. Is it okay to bypass the breaker box? I have my original charge controller controller connected directly to my battery terminals
    with an inline fuse for the positive wire. Could I connect a second charge controller to the battery terminals in the same way? Assuming both charge controllers have over-charging protection.

  29. I'm running two Victron Charge Controllers connected to the same battery bank as, i ran out of capacity on one of the controllers. I just made sure each is set for the same battery profile. Very handy that technology allows this.

  30. Hi, my name Stephen Welsh, I'm a certified marine technician and I will like to give you a bit of advice regarding the above video and connecting charge controllers in parallel.

    If you run out of capacity on a charge controller the best thing to do is obtain a charge controller with higher amperage that can carry all the panels at once, it's called a charge controller/regulator because its sole job is to regulate the Voltage and Amps so you will not over charge and destroy your battery in that case.

    Here's what actually happens when two or more controllers are used in parallel, lets call them controller A and controller B. Both controllers will start charging in full capacity (bulk) as seen in your video above, but when the volts get up to the set bulk charging voltage let's say 14.2 or whatever you have it set at, controller A will see the battery voltage at 14.2 and thinks that the battery is getting full. Therefore, it will quickly go into absorption and then into float prematurely, while controller B struggles for the rest of the day trying to do all the work and thats because controller A thats in float putting out little or no amps thinking the battery is full and take the rest of the day off. If you're running a system smiler to this,
    two 50 charge controllers feeding the same battery bank with 30 amps each from separate panels (total 60 amps). If you are running that kind of set up please monitor your system read out and you will see one charge controller working three time harder than the other, a easy way to tell is one always hotter than the other.

    The only way you can put two or more charge controller in parallel without having the problem I described, is by using charge controllers that could link with each other like master and slave.

    Its best to put all your panels on one charge controller. If you thinking of adding panels in the future, buy a charge controller that allow you to do that in the future, hope this helps.

  31. Generally speaking, this is a bad thing to do. Chargers do NOT like to see other chargers on the same setup, because it can "confuse" them. For example, if a single charger stops charging briefly to check the battery voltage to get an idea where it is in its charge curve, and there is another charger doing the same, then perhaps the first charger will see the boosted voltage of the 2nd charger and think the battery is in a higher state of charge, and rolloff the charge power some.

    What would be better (and a setup I am very fond of), is having 2 charge controllers each wired only to one of two 12V batteries in series. That is, the battery bank is 24V and so is the input requirement of the inverter, but each of the 2 batteries wired in series has its own 12V charge controller so it gets a more "tailored" charge. That way if one of the 2 batteries is run down a little more, the charge controller will "see" that and charge it longer than the other battery that was more topped off to begin with.

  32. What about if you have two solar charge controller and two different types battery bank say like 2×200amp gel batteries and 2×100 deep sealed lead battiers

  33. This is means that when we are using two controllers the current of the surse going double. What in case we use three or for controllers the current increasing three or four times up!!!!! The only thing that happent is the one controller effective the other creating wrong mesurments. Is'n it or no? Thanks a lot.

  34. Bad "advice" people. DON'T do this. Just because it briefly appears the charge amps are additive is not proof it "works well". What will happen when the battery bank approaches nearly full? Will it taper off correctly? I don't see this being tested here.

    A MUCH better solution is to just divide up your battery bank so that one charge controller sees half of that battery bank and the other charge controller sees the other half. For example, if I had a 12V system with a single charge controller and I maxxed it out with the maximum number of solar panels but I then wanted to double my solar power, I would double my number of solar panels, get another 12V controller, and convert my system to 24V, but have each 12V controller charge only one 12V subbank each.

    Usually when you expand a system (in this example doubling the power), it is better to increase voltage rather than leave it at 12V, however, there are exceptions such as if you insist on keeping it at 12V so if you get many cloudy days in a row, you can use a running (idling) car to charge your battery bank. I can get 70A of charge current this way using very little gasoline.

    What this woman is describing here may work with some charge controllers but most are NOT designed to work that way. That is similarly as bad as putting 2 regular battery chargers on the same battery at once. Some can handle it, some will not. In general you should NOT do this. However in a 24V series setup, many chargers will allow you to charger each 12V battery using a separate charger without having to first break the series connection between the 2 batteries.

  35. I cant seem to do this with renolgy tracer mppt at all I called tech support they said it will not work with renolgy ,one controller always turns off is there a way to do this some how with diodes maybe thanks

  36. I have used 2 chargers , 1 60A and 1 45A, If i conbinethem then one will not charge, they are not because one is pulling up the power and the other one than thinks that the battery is full. I am using 2 PWM charger. In your example you are using 2 types.! This is for just a PWM situation not a correct way to charge.

  37. What about charging two separate battery banks with the same solar panels? I have 60A charge controllers, 7x205w solar panels, my first battery bank has 36 deep cycle batteries, wired for 12 volts my second bank has 8 batteries wired again for 12 volts can I simply branch out the solar power to feed my second charge controller to charge my second battery bank?

  38. So you wire both MPPTs into the bus bars and then to the batteries? I’m trying to see where they join together. I want to make sure this is how they are wired. As long as both MPPTs go to the two bus bars and then to the battery they should be good… correct?

  39. Amy: I have 1 Solar panel and I want to add a 2nd controller. o charge my 2nd project while the 1st Project is correctly hooked up the panel should handle it if not mistaken thank you any advice is appreciated.

  40. I have 3kw solar panel and I have 2 solar charger controller. I'm not sure if I can wiring two LOAD [Output] controller in the same INVERTER

  41. Why the negative of one panel goes to opposite controller? Can I do the same if one controller is PWM and the other is MPPT ? Thank you

  42. I just found the schematic is wrong, you should make a video about it. It looks you're only concern with selling products. Very disappointed!

  43. You want to take a 20amp charge controler and get 40amps you got to hook them up postive to negative and use one postive to battery and one negative to battery thats the only way your going to take two and make it like one you want to rase the amp you do it the same way you get 24 volts from two battetys postive to negative then you have 24 volts so charge controler postive to negative you got 40 amps useing two 20 amp charge controlers hook up in parallel want get that series will

  44. I have two identical 300Watt 48volt turbines that I want to connect together electrically so I don't have to use/buy two charge controllers. Can a single charge controller can handle the combined current?

  45. Looks like you have the positive (or negative – your choice) swapped coming from the panels into the charge controllers. Switch one or the other and you'll have the panels isolated down to the controller they belong to. In your schematic they're mixed up.

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