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Can I get by with a budget Chinese mfg'd 40 amp MPPT charge controller?

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  • #1

    Can I get by with a budget Chinese mfg'd 40 amp MPPT charge controller?

    For 4 x 250 watt solar panels (1,000 Watts) wired in series-parallel, can I eek by with an inexpensive Chinese 40A MPPT charge controller or will I need a 60A charge controller? The panel parameters are as listed here:

    Voc = 36.9
    Vmp = 29.8
    Ioc = 9.09
    Imp = 8.39

    The actual manufacturer of the Chinese MPPT charge controller lists its PV max at 1,040 Watts (meaning that 4 x 250 Watt panels are OK) and its max panel open circuit voltage at 150V (meaning, as as been explained to me in a different forum thread that I must wire them 2 in series x 2 in parallel). The charge controllers rated "load current" is 20A and its rated "battery current" is 40A. But what scares me is that one retailer in the USA for this very charge controller says panel Watts should be limited to 800 max (meaning that 4 x 250 watt panels are way over the limit).

    I'm not sure if forum rules would permit me to mention the specific budget Chinese mfg'd charge controller I'm considering. I will do so if it is OK and if it is relevant to coming to the correct answer.
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  • #2
    You are asking for an opinion so here is mine. Buying a no name Chinese charge controller is one strike, running it near max load is two strikes. It may be a "budget" item but if its cooks, good luck getting it replaced, its highly likely that you end up buying the namebrand anyhow and then the budget model cost you get to chalk buying Chinese to experience.

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    • #3
      Charge controller ratings are output amps to the battery, so 1,000 PV watts would equal
      12V = 83A
      24v = 42A
      48v = 21A
      Generally, the panels only put out 80% of their nameplate wattage. So, without knowing what voltage your battery bank is, I can't answer
      Powerfab top of pole PV mount (2) | 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

      Comment

      • #4
        Sorry, it is a 24 volt system that I'm contemplating.

        Comment

        • #5
          What is your fallback if that cheap MPPT is a PWM with a MPPT sticker on it ? Any reason to stay at 24V vs 48V (if you have not bought any gear yet)?

          Seriously look at the Morningstar MPPT 60 with the built in ethernet. just plug it into a router and you have wireless monitoring, skip the $100 display panel.
          Powerfab top of pole PV mount (2) | 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

          Comment

          • #6
            I guess "contemplating" was a bad choice of words on my part, and the better term would have been "building". I already have the 24V inverter and my Chinese charge controller will be arriving next week. There are a couple end user YouTube videos of it being tested and confirmed to be MPPT. Can I reveal the charge controllers brand name and model number on the forum? I'm trying to put together a highly budget oriented system more for self education purposes (prior to committing to a larger system) than for goal oriented practicality (which will be a primary consideration for a larger future system).

            If I have to cut down from 4 panels to 3 to keep from frying the charge controller that will be chalked up as part of the learning curve. Perhaps if I have to go that route I can go to 3 x 275 Watt panels as opposed to 4 x 250 Watt?

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            • #7
              1000 watts for 40 amp 24 volt charge controller is fine, you hardly get the name plate power all the time, also there are losses in the wire and weather conditions. the question is not if the charge controller can take the panels wattage but if it last long because it is not one of the high quality products.

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              • #8
                Originally posted by Silver_Is_Money View Post
                I'm not sure if forum rules would permit me to mention the specific budget Chinese mfg'd charge controller I'm considering. I will do so if it is OK and if it is relevant to coming to the correct answer.
                Yes, which CC are you wondering about?

                Comment

                • #9
                  It's the new Tracer model 4215BN MPPT charge controller. 40A and 150V. The instruction manual says PV Watts should never exceed 1,040 when used in a 24V system. But my concern is if the 1,040 Watts figure is to be taken at face value, or to be derived from applying a 1.2 to 1.25 multiplier to a lesser Watt value, meaning that in reality PV watts can not exceed something akin to 830 to 865 Watts for this charge controller. Sort of like applying the 1.25 safety factor to series Voc panel voltage to be on the safe side and never exceed 150V, only for Watts. Somewhere I believe I read where system PV Watts can well exceed the sum total of STC rated panel Watts under certain circumstances. That's what made the "Watts factor" (safety valve) concern pop into my head.

                  Short version: Watts factor or no Watts factor?

                  Comment

                  • #10
                    Use the watts listed on the sticker on the panels, as the calculation basics for the controller.
                    Powerfab top of pole PV mount (2) | 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

                    Comment

                    • #11
                      im using a chinese 30 amp mppt CC with 3 x 250w 36v solar panels wired in parallel on a 24v 200ah battery bank, so far works great when the sun is out.

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                      • #12
                        I presented an "Amazon Question" to one of the companies that is offering this controller through Amazon.com and they replied that it will work fine with 4 x 250 Watt solar panels.

                        Comment

                        • #13
                          Originally posted by almac View Post
                          im using a chinese 30 amp mppt CC with 3 x 250w 36v solar panels wired in parallel on a 24v 200ah battery bank, so far works great when the sun is out.
                          Usually an MPPT CC has a much higher DC input voltage rating then a PWM type allowing you to wire panels in series instead of parallel.

                          So unless the Voc rating for those 250w panels is > 40volts you should be able to wire them in series and be able to use smaller wire size as well as not needing an OCPD on each of the panels.

                          Comment

                          • #14
                            Originally posted by SunEagle View Post
                            Usually an MPPT CC has a much higher DC input voltage rating then a PWM type allowing you to wire panels in series instead of parallel.

                            So unless the Voc rating for those 250w panels is > 40volts you should be able to wire them in series and be able to use smaller wire size as well as not needing an OCPD on each of the panels.
                            the voltage reads at about 36v with a voltmeter , the max pv open circuit voltage is 65v on the CC . so im stuck with parallel

                            Comment

                            • #15
                              Originally posted by almac View Post
                              the voltage reads at about 36v with a voltmeter , the max pv open circuit voltage is 65v on the CC . so im stuck with parallel
                              Too bad about that 65V max on your CC.

                              IMO that is one of the differences between a quality MPPT CC and a lower cost one. What you save on costs you lose on flexibility.

                              Comment

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