Max panel wattage input to Charge Controller

dave6801
dave6801 Registered Users Posts: 6 ✭
in General Solar Power Topics #1
I Have a Pulse PM 60 PV Charge Controller, which is rated for 60 Amps. My system is set-up for 12V and I would like to know the max total wattage that my panels can output for this charge controller. Thanks Dave
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #2
    Re: Max panel wattage imput to Charge Controller

    Roughly speaking 60 amps @ 12v = 720 watts.

    I looked for a "Pulse PM 60 PV Charge Controller" and could not find it... who is the manufacturer?
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  • dave6801
    dave6801 Registered Users Posts: 6 ✭
    #3
    Re: Max panel wattage imput to Charge Controller

    Thanks Mike, The manafacturer is Pulse Energy System Inc. The controller is 10 years old and obselete. If I wanted to run more panels with a total wattage that exceeds 720 watts can I find a higher amperage charge controller. 60 amps seems on the max side? Am I able to run 2 or more charge controllers somehow? Thanks Dave
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Max panel wattage imput to Charge Controller
    dave6801 wrote: »
    Thanks Mike, The manafacturer is Pulse Energy System Inc. The controller is 10 years old and obselete. If I wanted to run more panels with a total wattage that exceeds 720 watts can I find a higher amperage charge controller. 60 amps seems on the max side? Am I able to run 2 or more charge controllers somehow? Thanks Dave

    80 Amps is about the most you'll see (Outback's FM 80).

    There's absolutely no reason you can't run multiple PV arrays with separate charge controllers feeding the same bank of batteries.

    60 Amps is capable of charging a 600 Amp/hr battery bank. Even at 12 Volts, that's a fair amount of power (3.6 kilowatt/hours at max DOD). What's your application?
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #5
    Re: Max panel wattage imput to Charge Controller
    The manafacturer is Pulse Energy System Inc
    This is the controller Trace used in most of their wiring panels, PC250 and PC500 panels.
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  • dave6801
    dave6801 Registered Users Posts: 6 ✭
    #6
    Re: Max panel wattage imput to Charge Controller

    Thanks, What I have is 2 120 watt @ 12v panels, a pulse 60amp charge controller, six 6volt batteries set-up in pairs of 12volts and a freeedom 458 series combi inverter/charger. sounds like I can add 4 more 120watt 12volt panels with no problem.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Max panel wattage imput to Charge Controller
    dave6801 wrote: »
    Thanks, What I have is 2 120 watt @ 12v panels, a pulse 60amp charge controller, six 6volt batteries set-up in pairs of 12volts and a freeedom 458 series combi inverter/charger. sounds like I can add 4 more 120watt 12volt panels with no problem.

    With the usual caveats about needing to add fuses to each panel when you parallel more than two and the necessary sizing of wire to handle the increased potential current load, yes. :D

    "six 6 Volt batteries" - three banks of two each, right? Do I need to give the parallel battery wiring lecture here? :p

    If those are the usual 225 Amp/hr batteries they sure aren't going to be happy with just 240 Watts of panels. That's why you want to add more, right? It's a good plan. :D
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #8
    Re: Max panel wattage imput to Charge Controller

    Go by the specified MPP current, not the wattage of the panel.

    Typical panels for 12v charging are specified at 25 deg C wattage which has a MPP voltage of about 18-19 vdc. This MPPT voltage, at 25 deg C is used to specify the panel power rating. The reason that this panel voltage seem high is because in hot summer with direct sun hitting panel the panel temp will be high and the MPP voltage will drop to about 15-15.5 vdc which barely gives you an equilize capable voltage.

    For a PWM controller it is a MOSFET switch that connects and disconnect from panel. The panel, being an illumination based current source, will put out the approximate MPP current across the battery voltage range. For a 180 watt specified panel the MPP current will be approximately 180 watts / 18v = 10 amps. When PWM connects to battery it will be approximately 10 amp (at full sun), regardless if the battery is at 11.8vdc or 13.0 vdc. For a discharged battery of 11.8vdc, you will get 11.8v X 10 amps = 118 watts from panel, for 13.0vdc battery, you will get 13.0v X 10 amps = 130 watts from panel. The MPP current has a very small temp coefficient. At a bulk voltage of 14.3 vdc, the max from panel is 143 watts.

    The max current rating on the PWM controller is based on heat dissipation on the MOSFET switch. Given a certain MOSFET with an Rs (series resistance), the max power dissipation will Rs X Imax^2.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Max panel wattage imput to Charge Controller

    Listen to RC; he knows what he's talking about!

    Another caution is: location, location, location. Both where the panels are located on your site (will they get full insolation or not) and where your site is. In the South there's the problem of high temps decreasing output. Here in the North we worry about super-conducting in the extreme cold of Winter.

    Margins, safety factors, erring on the side of caution.
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  • dave6801
    dave6801 Registered Users Posts: 6 ✭
    #10
    Re: Max panel wattage imput to Charge Controller

    Thanks for all the advise Dave
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  • dave6801
    dave6801 Registered Users Posts: 6 ✭
    #11
    Re: Max panel wattage imput to Charge Controller

    appears that the panels I wanted to add to my system are 24 volt and my existing panels are 12v, can i mix different voltage panels.
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #12
    Re: Max panel wattage imput to Charge Controller

    Yes BUT, through separate charge controllers!
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  • dave6801
    dave6801 Registered Users Posts: 6 ✭
    #13
    Re: Max panel wattage imput to Charge Controller

    maybe I can wire my two 12v panels together to make a 24v and add the 4 24v panels.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #14
    Re: Max panel wattage imput to Charge Controller

    Ideally--you want to add panels in series whose Imp currents are within 10% of each other.

    And in parallel, those whose Vmp is within 10% of each other (if MPPT charge controller). If PWM, then Vmp should be >~Vbatt-charging+2volts minimum for the lower Vmp string/panel (miss-match on high side of voltage does not matter with PWM--as long as it meets the min/max of the controller+bank requirements).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #15
    Re: Max panel wattage imput to Charge Controller
    dave6801 wrote: »
    appears that the panels I wanted to add to my system are 24 volt and my existing panels are 12v, can i mix different voltage panels.

    If you have a 12V battery bank, and try to use 24V panels, you will only see about 50% of the panel wattage into your battery. (With a simple FET PWM controller)

    A MPPT charge controller will transmogrify the panels 24V to 12V for charging the battery, with no loss in watts
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #16
    Re: Max panel wattage imput to Charge Controller

    When you reach float or bulk limits on the charge controller, and the controller starts chopping, the 24v panels current will flow into the 12v panels unless you have blocking diodes on the 12 v panels. The extra backwash current into the 12v panels might damage them.

    As described previously, don't put the two 12's in series. You will lose effectiveness of one of the panels in series. If you get an MPPT controller you can tie the two 12v panels in series. You might not get the maximum MPP voltage due to the 24v and two series 12v may not have exact matching MPP voltage points but should be close.

    Until you get a second controller, your best bet is make sure you have blocking diodes on the panels and tie all four in parallel. The 24 v panel will only be putting their MPP current into the battery so your are losing over half their wattage rating.

    Doubt you have reached controller input voltage spec limit but make sure the 24v panels Voc doesn't exceed controller max voltage spec under coldest panel temp (about 56 to 57 vdc).

    The vocabulary word of the the day is "transmogrify" :)
    'Jocular' to change or transform into a different shape, especially a grotesque or bizarre one.

    Someone has been playing too many video games.
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  • System2
    System2 Posts: 6,290 admin
    #17
    Re: Max panel wattage imput to Charge Controller

    I also have a PC-60 with BP-120 panels -48 volt and a SW5548 inverter. After 10 years my controller burned up. I'm looking to replace it with something better in terms of data logging. Any suggestions would be welcome.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #18
    Re: Max panel wattage imput to Charge Controller
    Cliffman wrote: »
    I also have a PC-60 with BP-120 panels -48 volt and a SW5548 inverter. After 10 years my controller burned up. I'm looking to replace it with something better in terms of data logging. Any suggestions would be welcome.

    There's data logging, and then there's data logging.
    Most of the "higher end" (i.e. expensive) charge controllers keep track of information for a number of days. Some have the ability to interface with computers so you can build a database of years' worth of info.

    Charge controllers: http://www.solar-electric.com/chco.html

    It all depends on how much you want to keep track of, for how long, and of course what the budget is.
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