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  • Newbie with a couple of questions

    Hi all new to the forum and new to solar in general just built a shed on my allotment here in the U.K. And got myself a little solar set up which I am currently using for lighting in the shed and a USB radio all seems to be working well and batteries are charging even in the uk winter weather this is the setup I've got

    2x25w solar panel
    A pwm 10a controller
    2x110ah leisure battery lead acid

    My questions
    are can I put 2 watt meters on the controller to battery wire 1 in reverse direction to measure what goes in and what's coming out of the battery
    And is this little system big enough to add 2x10w floodlights to along with a small water pump for irrigation
    All lights are led and the system is set up in 12v configuration at the moment

    Thanks all for looking and any advice or help would be greatly appreciated
    Attached Files

  • #2
    Welcome.
    Enjoy the system while it's working, But I think you are going to need more panels. 50W of panel, in GOOD, well aimed position, can be expected to produce 40 watts of power at best. That translates to about 2.5 amps of charge current for only a couple hours a day. On cloudy days, expect much less,
    The panels can manage to keep the batteries topped off, but if you deplete them much at all, they will be unable to recharge very fast,
    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
      I agree with Mike. With a 12v 220Ah battery system you really need about 22 amps of charging which would be about 300 watts of panels with a 30A MPPT CC or ~ 500 watts of panels using a 30A PWM CC

      Comment


      • #4
        Thanks for the quick response how much more wattage in panels would you suggest have been monitoring the cc and as you said does take a while to charge them back up
        Would changing it to a 24v set up as I think my cc has the option to set the load voltage so can leave lighting as is
        Thanks

        Comment


        • #5
          Originally posted by Notty1975 View Post
          Thanks for the quick response how much more wattage in panels would you suggest have been monitoring the cc and as you said does take a while to charge them back up
          Would changing it to a 24v set up as I think my cc has the option to set the load voltage so can leave lighting as is
          Thanks
          Changing the battery system to 24v doesn't change the amount of panel wattage. You still need about 300watts with a 15A MPPT type CC since you are charging at 24Volts you now only need about 11amps.

          Comment


          • #6
            Originally posted by SunEagle View Post

            Changing the battery system to 24v doesn't change the amount of panel wattage. You still need about 300watts with a 15A MPPT type CC since you are charging at 24Volts you now only need about 11amps.
            Thanks for the info will look into more panels is bigger better i.e. 1x300w as apposed to 3x100w
            And what are you thoughts on using to 2 watt meters

            Comment


            • #7
              Originally posted by Notty1975 View Post

              Thanks for the info will look into more panels is bigger better i.e. 1x300w as apposed to 3x100w
              And what are you thoughts on using to 2 watt meters
              If you are looking for a "spot" meter the Tenergy makes a pretty good one that will provide an accurate reading of the DC voltage, amps and watts. I really don't know of any low cost recording DC watt meters that will accumulate the amount of watts being sent to the battery and coming out of the battery.

              Comment


              • #8
                Originally posted by SunEagle View Post

                If you are looking for a "spot" meter the Tenergy makes a pretty good one that will provide an accurate reading of the DC voltage, amps and watts. I really don't know of any low cost recording DC watt meters that will accumulate the amount of watts being sent to the battery and coming out of the battery.
                That's why I was wondering if two connected opposite would work I have found some on flea bay just wondering if 2 connected that way would cause any problems

                Comment


                • #9
                  Originally posted by Notty1975 View Post

                  That's why I was wondering if two connected opposite would work I have found some on flea bay just wondering if 2 connected that way would cause any problems
                  No. Technically you have 2 circuits. One is the battery charging circuit between the CC and battery. The other is the battery load circuit between the battery and inverter or DC load.

                  Just make sure you use fuses before each meter. They protect the wire and the meter.

                  Comment


                  • ButchDeal
                    ButchDeal commented
                    Editing a comment
                    He likely has the load hanging off of the CC. Don't do that. put the load on its own not through the CC.

                • #10
                  I do have the loads coming off the cc is that a problem

                  Comment


                  • #11
                    The reason they are called Charge Controllers, is they are designed for Charging. Load Control is a separate function, and charge controllers emulate it with a 20 cent transistor which often burns out unless it's only powering a very light load.

                    But the main problem was discovered in the 70's when PV panels were expensive, and folks used small panels with large battery banks, When the bank gets low, and takes 4 days to charge back up, the cells are busy sulfating themselves to death, first month you have a 100ah battery, 2nd month it's degraded to 80ah from sulfation, 3rd month down to 70ah - so on and so on. At some point, after a year, the bank has degraded to the point it won't run loads overnight anymore and the batteries are shot.
                    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
                      Originally posted by Notty1975 View Post
                      I do have the loads coming off the cc is that a problem
                      It could be a problem. Most of the cheap CC have very poor circuitry where the Load Terminals are not size for much and can easily be overloaded.

                      As both Butch and Mike have suggested it is better to connect the load to the battery if DC or have the DC to AC inverter connected to the battery. Don't use the load terminals on the CC.

                      Comment


                      • #13
                        Originally posted by SunEagle View Post

                        It could be a problem. Most of the cheap CC have very poor circuitry where the Load Terminals are not size for much and can easily be overloaded.

                        As both Butch and Mike have suggested it is better to connect the load to the battery if DC or have the DC to AC inverter connected to the battery. Don't use the load terminals on the CC.
                        The Load terminals are often used for controlled lighting, with the CC detecting when it is dark by monitoring the panels.
                        The Load terminals can also be used to control a relay which will disconnect or turn off the inverter when the battery voltage goes too low. But the fixed cutoff on many inexpensive CCs is too low a voltage to properly protect the battery.

                        Even expensive CCs do not have Load terminals suitable for feeding an inverter of useful capacity.
                        SunnyBoy 3000 US, 18 BP Solar 175B panels.

                        Comment


                        • Notty1975
                          Notty1975 commented
                          Editing a comment
                          I have the option on the cc to change the cut off vaultage and the cc can take up to 6mm2 wiring

                      • #14
                        50 watts of panels on a 220 AH 12 volt battery? Get off the load terms and connect directly to the battery post.

                        Try again like 300 watts.
                        MSEE, PE

                        Comment


                        • Notty1975
                          Notty1975 commented
                          Editing a comment
                          I've gotten that idea already thanks like I said I'm new to solar power

                      • #15
                        I see so basically run everything directly of the battery's obviously fused but if I kept it as a 12v system would I need a dc to dc converter or should they run ok slightly over vaultage obviously I would need something then to convert it from 24+v down to the 12v needed for the lighting
                        That would mean I could connect both watt meters easily and then could also get a higher vaultage pump for the irrigation system meaning less current draw do the dc to dc converters use/waste a lot of energy

                        Comment

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