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  • Opinions sought on panel charge controller.

    Hi all, first post and seeking advice, well nothing new there right? 8>)

    Whilst waiting for my account activation I posted this question on one of the off road forums that has a solar power section, now having access I would like to hear from forum members who can no doubt draw from broader experiences.

    Panel spec..jpg


    For various reasons I had to change the solar panels on my off road 4x4, there were 2 x 100w panels, one fitted horizontsl to the roof rack and the second on a wandering lead of about 15 metres, both panels were wired in parallel to a 20 amp PWM type controller. Those panels maintained two marine wet cell batteries or around 3 years with no real problems. I only have a small 50 litre fridge to keep working, it draws around 4 amps, but of course only a few minutes out of each hour. On odd occasions when camping and getting two consecutive days of poor sunlight did I consider running the engine but with the VSR protecting the start battery I decided to leave be and sure enough no problems.

    Those 2 panels are to be replaced by 2 of the spec seen in the picture above. The difference is now that both are to be fitted to the roof rack and both will be horizontal, given there will be less cable length in use, but no ability to track the sun, would there be any mileage in swapping the PWM controller for an MPPT type but still wired in parallel?

    BTW, I tried a medium size picture but could not read the spec, hence the large size.

    Any thoughts would be appreciated.

    regards

    Dave
    Last edited by DMH; 01-25-2019, 03:52 PM.

  • #2
    With 150 watts and an MPPT you may generate about 12 amps max. (150w / 12v = 12.5a) no matter how they are wired as long as you don't exceed the maximum DC input voltage of the CC.
    With a panel Voc = 21.4v you could generate 42.8 volts x 1.15 = 49.2volts depending on the temperature. If your MPPT CC has an input DC rating of 100V you will be ok. If it has a max DC input of 50v you may exceed it during cold weather.

    Wiring those panels in parallel to a PWM type CC will get you about 9 amps max ( 2 x 4.45amp = 8.9amps). That calculates to just over 100 watts (8.9a x 12v = 106.8w) so you would be losing about 33% of your panel wattage.

    It depends on the cost of the MPPT compared to losing 50watts of generation.

    Comment


    • #3
      Thanks for the reply and information. A basic MPPT to cover 20 amps is only around 20 euros, I will look at the specs and see if they are suitable. 33% is worth the effort to purchase and swap out the PWM IMO.

      Thanks again,

      regards

      Dave

      Comment


      • #4
        No it's not 20 euros, those are fake. Don't throw your money away; for 20 you not going to get not even a real pwm. A real mppt at 20A starts in the region of 75-80 euros.
        Look at victron blue solar charges to have a idea of the cost of a real mppt. There are others on EU market as well.

        Comment


        • #5
          Hi Raul, I will take your comments on board. The PWM I presently have is a typical ebay unit, TBH it has performed how I thought it should over the last three years, I based my purchase consideration on this and ordered a cheap MPPT unit from ebay. In your opinion this is going to be a waste of money on my 4x4?

          regards

          Dave

          Comment


          • #6
            Hi, I have looked at the Victron range and
            Last edited by DMH; 01-26-2019, 11:27 AM.

            Comment


            • #7
              There are a number of fake MPPT charge controllers on eBay but, there are plenty of decent fairly inexpensive models out there as well. Look at the EPEver line of controllers There are many contributors on this forum who use them and they are what they say they are.
              2.2kw Suntech mono, Classic 200, NEW Trace SW4024

              Comment


              • #8
                Hi and thanks for that. I did write in my last post about seeing fakes with mission critical products however half the post disappeared?

                I noted I had seen s Victron unit for around

                Comment


                • #9
                  OK there is a problem with my account, a large portion of my posts are not appearing?

                  Mods?

                  Regards

                  Dave

                  Comment


                  • #10
                    Originally posted by DMH View Post
                    OK there is a problem with my account, a large portion of my posts are not appearing?

                    Mods?

                    Regards

                    Dave
                    Sometimes the post will be cut off if you "paste" a lot of text. Another way our software cuts off a post is if you use an apostrophe. For some reason it takes that character as spam.

                    Comment


                    • #11
                      Hi and thanks for the quick response.

                      I did not cut and paste anything but did use open and closed brackets, sound familiar?

                      regards

                      Dave

                      Comment


                      • #12
                        using brakets is bad, they delimit a lot of things on message boards [
                        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


                        • #13
                          Sometimes cut and paste fails for me, so I type a few letters. At that point the cut and paste works,
                          I go back and delete any extra letters. Bruce Roe

                          Comment


                          • #14
                            Thanks for that guys, I will try to remember that. As I had already purchased the MPPT cheap from ebay when I saw the post from Raul, and I now have two brands to choose from. FWIW I did connect the two new panels in parallel to the PWM, and with the midday sun low in the sky I did see 2 amps from each panel as they laid flat on the roof, if nothing else it show the panels are working.

                            Thanks to all who have offered help, the plsn is to fit the cheap MPPT, as it is the same size as the present one, I will not have to alter my power distribution setup. As I am in the fortunate position to be able to swap connections from PWM to MPPT in a moment, I may try that? If I have no measurable advantage I may purchase one of the more expensive units.

                            I will update at a later date,

                            Thanks again

                            Regards

                            Dave

                            Comment


                            • #15
                              Originally posted by DMH View Post
                              OK there is a problem with my account, a large portion of my posts are not appearing?

                              Mods?

                              Regards

                              Dave
                              Most important, do not use "smart quotes" where the opening and closing quote marks are different symbols. The occurrence of a smart quote character can truncate your post.
                              The smart quotes are represented by a multiple byte sequence and one of those byte values is not allowed in a post.
                              SunnyBoy 3000 US, 18 BP Solar 175B panels.

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