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  • RV solar noob here

    I recently acquired a Wiese 100w solar panel with an HP 2410 controller. I dry camp with my trailer frequently and am looking to just keep my 2-12v batteries topped up. We don’t use a ton of power, nothing 110 off an inverter. I have two questions: When I hooked the system up, the connections for the batteries and the panel were obvious, but it also instructed me to hook up the load. Since the load (trailer) is already connected to the batteries I assumed this was unnecessary. Secondly, the controller shows proper output voltage and existing levels in the battery (consistent with the trailer readings). However, after a couple cycles the controller shows a greatly reduced battery level, ie from 75% to 15-20%. This does increase with charging, but when I unhook the panel it always goes to 100% battery level even if it showed 45% hooked up. Any thoughts out there?

  • #2
    There are so many low grade solar controllers out there, it's impossible to figure out what is wrong.
    You can do it right, or you can do it cheap. You now see the results of cheap.

    Now a 100w panel is not going to do much for you, figure an average of 4 usable solar hours a day, and a poorly aimed panel, in full sun, you can expect to harvest about 300 watt hours daily.

    That would recharge usage of 240 watt hours. You can allocate that usage anyway you want
    50w fan for 4.8 hours
    20 watts of lighting for 12 hours
    Charging a cell phone for 6 hours

    Figure the wattage of the load, x hours and you get watt hours Don't mess with amps & volts

    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


    • #3
      Originally posted by Chasleyko View Post
      I recently acquired a Wiese 100w solar panel with an HP 2410 controller. I dry camp with my trailer frequently and am looking to just keep my 2-12v batteries topped up. We don’t use a ton of power, nothing 110 off an inverter. I have two questions: When I hooked the system up, the connections for the batteries and the panel were obvious, but it also instructed me to hook up the load. Since the load (trailer) is already connected to the batteries I assumed this was unnecessary. Secondly, the controller shows proper output voltage and existing levels in the battery (consistent with the trailer readings). However, after a couple cycles the controller shows a greatly reduced battery level, ie from 75% to 15-20%. This does increase with charging, but when I unhook the panel it always goes to 100% battery level even if it showed 45% hooked up. Any thoughts out there?
      Well here is a quick run down of the setup.
      Solar panel to charge controller, the battery to the charge controller and as far as the load is concerned, you don't need to connect anything. If you look at your handbook for the controller you can turn the load on and off at will. I am presuming you are connecting the inverter directly across the 12V batteries and not trying to use the load out.
      I would suggest buying an MPPT controller, given it is more efficient than the PWM controller you have. You can pick up a 20A MPPT controller for around the same price as the HP 2410

      If you take into account what Mike has said above, then you need to be looking at what is draining power. The only thing you have on is the inverter and I know from personal experience that these are just power hogs.

      An inverter will draw power constantly, no matter if you are using the 110V or not, disconnecting the inverter via a switch and turning it on, only when you use it is the obvious way to save power.
      Just to pre-empt the question about the inverter being turned off at the switch, that just turns the inverter output off, leaving the inverter itself, on and drawing power.

      Just remember that whatever you connect to the batteries will drain power, if it is turned on.

      Comment


      • #4
        Thanks for your response guys I don't have an inverter, so I never run anything that uses 120v unless I'm plugged in at a campground. I use only the 12v side of the system when dry camping, and generally can run for three days off my 2-12v batteries. I got a single 100w panel solely to be able to stretch that 3 days if I want to. Asterix my controller shows the load in manual setting, but havent gone into the menu to see if it's on or off. Would it matter if nothing is connected to the load side of the controller? I will follow your suggestion and find a MPPT controller to see if it will show current values accurately.

        Comment


        • #5
          slow down. A MPPT controller is wasted on a single100w panel. There is nothing for it to do except run in PWM mode. MPPT controllers take moderate DC voltage (20-90V) from several panels in series, or a 50V 300w grid-tie panel. The MPPT tracks the array to its most efficient voltage and downconverts that to your battery charge, transforming volts for more amps.

          PWM controller : amps in = amps out 18V 3Ain = 14V 3A output (54w in , 42w out )
          MPPT controller : watts in = watts out 87V 3A in = 14V 18A output ( 260W in = 260W out)

          But that power gain comes at the cost of a much more expensive controller. Also, wires to carry 3A from the panels on the roof, or far away, are much less expensive than wire rated for 18A
          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
            Originally posted by Chasleyko View Post
            T Would it matter if nothing is connected to the load side of the controller?
            As far as needing a load, I don't know if there's a good way to answer that when the instruction manual says hook a load, and the only direction it gives is a "cutoff value like at 10.6 Volts," power is no longer supplied and perhaps a mention of "don't hook the battery to be charged to the load."

            I don't know how the circuitry inside is designed.

            What I did with my extremely cheap PWM controller is not hook the load to it, despite no direction from the manufacturer. I hooked it to a 100 watt solar panel anda 96 ah 12V battery and a 400 watt inverter to a battery that powered a 19 watt light, and left that on for only a few minutes. That is what I consider my emergency household generator, Which I would only use to charge 4 to 8 USB charging devices.

            That's only a limited experience I have with a single cheap PWM charger,

            Years ago I looked at cheap homemade wind power generating devices, and these needed a load to dump any power in should the windmill get hit with a sustained burst of wind creating too much power. In this case the guy used a space heater above the fireplace to bleed off the extra energy.

            From my limited understanding, the load outputs on the PWM chargers are not intended to "Bleed off" the extra energy produced, but will power a DC device that does not draw a lot of power and dies not need to be left on when panel voltage and battery voltage drop below that 10.6 VDC or whatever you set threshold.

            I think the only way to know for sure is to be an electrical engineer, and I was only an electronics technician for a few years three decades ago, so my understanding only scratches at the surface and sometimes dangerously.
            Last edited by chrisski; 07-31-2020, 04:51 PM.

            Comment


            • #7
              Thanks for your patience Mike. I’m just using the panel portable in front of my trailer. I’ve noted that the single panel will top up my batteries from 50-60% in 2-3 hrs with full sun. As I said before, the controller doesn’t seem to be reading battery levels accurately tho. So do I need a better PWM controller?

              Comment


              • #8
                Thanks chrisski. My son are an EE, and he said google it. Ha

                Comment


                • #9
                  The 100w panel might take 2 days to recharge that battery. If you have a regular car charger, throw it onto the battery for a day, so the battery does not become damaged from being in a constant low state.

                  Just about any < $50 entry level PWM controller should work for you. I'd not bother to get less than a 15A controller.

                  If you only plan on using a LED light and charging some USB gear, you will be OK for a few sunny days. It's hard to be sure what the USB loads are going to be, but the big battery will hold a lot of recharges before it goes flat.
                  Last edited by Mike90250; 08-01-2020, 12:03 PM. Reason: typo - bug should have been big
                  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


                  • #10
                    > A MPPT controller is wasted on a single100w panel. There is nothing for it to do except run in PWM mode

                    Both statements are trivially disprovable.

                    Comment


                    • #11
                      Originally posted by secessus View Post
                      > A MPPT controller is wasted on a single100w panel. There is nothing for it to do except run in PWM mode

                      Both statements are trivially disprovable.
                      [game on]

                      Of course you are right. and I'll do the math ( and assume 100% efficiency, and charging at 14v which I used before, and
                      assuming the MPPT requires no overhead voltage instead of the typical Vbatt x 130%)

                      MPPT
                      100w @ 18Vmp = 5.55a
                      converted to 14V gives 7.14 amps about 1.5A gain and you use a $200 controller to get there.

                      But since I don't know of any MPPT controllers that would actually work in this configuration, I'll stand by "it's going to run in PWM mode."

                      PV panels are generally hot, being in the sun, and that drives their Vmp voltage lower, and less likely to be able to have MPPT action happen.
                      exceptions - a really cold day that shifts the Vmp point to 20V might help.

                      And of course the newcomers don't always know there are really 3 kinds of charge controllers
                      a) PWM $30
                      b) genuine MPPT $200
                      c) PWM with a MPPT sticker over the PWM label $50 ( which works till the user gets a reliable meter and takes Vmp vs Vbatt readings and finds out he's been screwed )


                      So convince me how it works in real life for you. (MPPT with a single 100w 12v panel) . I want to be able to pass honest info along, and if you have something that works, share it.
                      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


                      • #12
                        > converted to 14V gives 7.14 amps about 1.5A gain and you use a $200 controller to get there.

                        It seems to me your underlying argument is that small MPPT configs are not worth the gain economically to you. Maybe not, that's up to you. There are other use cases where it might be worth it.


                        > But since I don't know of any MPPT controllers that would actually work in this configuration,


                        The only MPPT I know of that wouldn't work in that situation are the Victrons that have unsually high MPPT-initiation voltages (+5v, IIRC). And even then it doesn't have to be Vmp>=Vbatt+5, just panel voltage broadly speaking. Once initiated it only requires +1v.

                        The Genasun GVB MPPT series has a boost circuit and will charge from as little as 5v input.



                        > I'll stand by "it's going to run in PWM mode."


                        There are at least two situations where MPPT controllers are not running at the maximum power point and in my opinion PWM is not a useful description of either case:

                        * when the MPPT algorithm is not active due to insufficient Vpanel or other requirement (I think this is one you mean here). Victron's +5v requirement, or EpEver's apparent ~10w minimum. I don't observe this outside dawn/dusk so have not studied it carefully, the available power at such times being so minor. My recollection is that when the algo isn't running it's Vpanel == Vbatt with periodic sweeps. Heck, even PWM controllers aren't doing PWM in such situations; it's just a circuit with no pulses to modulate.
                        * when maximum power is not demanded. You've said elsewhere that "Generally, with MPPT chargers, as the batteries require less power, the charger reverts to PWM mode...". MPPT chargers typically move Vpanel off Vmp to another powerpoint that meets demand (usually toward Voc). . Watch Vpanel move around after Vabs is attained and compare that to your panels' published curve. I have argued elsewhere that calling MPPT controllers PPT controllers would keep people from getting hung up on the maximum part of the name.


                        > PV panels are generally hot, being in the sun, and that drives their Vmp voltage lower

                        Right, I am familiar with temp derating. Folks running MPPT in hot ambient temps would do well to shoot for higher Vmp.

                        The most popular 100w I know of (framed Renogy mono) has a Vmp around 18.9v, if memory serves. That panel would hold 14v+1 until ~98F ambient.



                        > b) genuine MPPT $200

                        I see you repeat this mantra often, and take issue with it. ("You can do it right, or you can do it cheap. You now see the results of cheap."). There are small MPPT controllers down to about the $50 mark. Yes, one has to pay attention to get a real one.

                        A 10A Chinese tracer/epever/epsolar 1210-series controller is about $50 from the mainland, or $60 off Amazon. My 40A 4210BN controller was less than $200.

                        Are Midnite Solar or Morningstar a better value for me at 3x the cost and for my use case? No. Am I going crap on them whenever they are mentioned just because they don't make sense for me? Nope. I am hoping you will follow suit, if for no other reason than there's a moderator badge on your avatar.


                        > So convince me how it works in real life for you


                        In the past I've run MPPT successfully on systems as small as 5A genasun mppt (GV5? back when serial numbers were handwritten) on a 60w panel, and 10A 1210 controller mentioned above on a 100w panel.

                        Forgive me if I say I think you have an entrenched position and cannot be convinced. I don't want to convince you; I want you to stop spreading FUD.









                        Comment


                        • #13
                          Our biggest problem is that most Noobs want to purchase cheap MPPT CC's which turn out to really be PWM type or pieces of crap and just dangerous. For the most part a low cost MPPT may or may not work efficiently with only a 100watt panel. You have to do the research first to find something that does.

                          Speaking for the Moderators on this Forum, we are not spreading Fear, Uncertainty or Doubt. We are trying to make sure people trying to save money not purchases something that most likely will not work. So while we may use a broad brush and put down all cheap MPPT type CC's we are really just trying to keep people from wasting their money.

                          Comment


                          • #14
                            > Our biggest problem is that most Noobs want to purchase cheap MPPT CC's which turn out to really be PWM type or pieces of crap

                            The solution to that problem is providing accurate information.


                            > For the most part a low cost MPPT may or may not work efficiently with only a 100watt panel.

                            As with ALL controllers. That is an excellent example of FUD.

                            > You have to do the research first to find something that does.

                            Agreed, regardless of price.


                            > So while we may use a broad brush and put down all cheap MPPT type CC's we are really just trying to keep people from wasting their money.

                            One could just as easily make the argument that telling people to spend 3-4x more to meet the same need is wasting their money. I won't make that argument since I don't know what's best for someone else.

                            Comment


                            • #15
                              Originally posted by secessus View Post
                              > Our biggest problem is that most Noobs want to purchase cheap MPPT CC's which turn out to really be PWM type or pieces of crap

                              The solution to that problem is providing accurate information. "The problem is that there are so many false MPPT type CC's it would take many pages to list them all. It is a little easier to just provide out thoughts on a particular CC that someone is looking to purchase."


                              > For the most part a low cost MPPT may or may not work efficiently with only a 100watt panel.

                              As with ALL controllers. That is an excellent example of FUD. "I disagree. We aren't instilling fear we are stating a fact that for a very large percentage of CCs that do not work well with a small wattage system. You can disagree but please don't label our posts as FUD."

                              > You have to do the research first to find something that does.

                              Agreed, regardless of price.


                              > So while we may use a broad brush and put down all cheap MPPT type CC's we are really just trying to keep people from wasting their money.

                              One could just as easily make the argument that telling people to spend 3-4x more to meet the same need is wasting their money. I won't make that argument since I don't know what's best for someone else. "I have never wasted my money by purchasing a quality piece of equipment. Sure I look for the lower or discount price on something before I buy something but saving a few $ usually tends to be wasted on lower quality. What I try to say is that the decision to purchase what they are looking at is up to the poster since each person has their own level of spending.. Some people get by with low quality equipment but others are greatly disappointed that their system is not working the way they thought."
                              Comments posted above in " "
                              Last edited by SunEagle; 08-01-2020, 05:51 PM.

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