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  • Shed light by 100W+25W 12V panels.

    Hi all.

    I have setup my shed to have lights using two PV panels, 100W + 25W.

    It looks now as I am producing more than what I expected to.

    As a result, I have introduced a 30ltr water tank that will be getting it's water from the outside butt and heat it up to 30C. This is to be used to wash hands and some garden tools. A small project.

    I have the charge controller and I am now wondering if I should connect the lights straight to the batteries and only use the load side of this charger to only pump in / heat up the water only when the voltage reaches a certain point.

    What do you think? Or should all loads be connected to the load side of this charge controller?

    Kind regards and much appreciated for any input given.

    Albert

  • #2
    Why not just get a thermal batch heater and be done with it in a simple manner ?

    Comment


    • #3
      Originally posted by J.P.M. View Post
      Why not just get a thermal batch heater and be done with it in a simple manner ?
      Hi.

      I have never heard of the name until now.

      In England we don't use that system as often as perhaps other E.U countries.

      Having said that, as I am overproducing energy, 8 amps at time, I just thought to use that extra in the way I have mentioned in my previous post.

      Still, to use your recommendation would crowed the top of the shed quite considerably and it is just a shed at the end of the day.

      Many thanks.

      Albert

      Comment


      • #4
        Originally posted by albertc30 View Post
        Hi.

        I have never heard of the name until now.

        In England we don't use that system as often as perhaps other E.U countries.

        Having said that, as I am overproducing energy, 8 amps at time, I just thought to use that extra in the way I have mentioned in my previous post.

        Still, to use your recommendation would crowed the top of the shed quite considerably and it is just a shed at the end of the day.

        Many thanks.

        Albert
        You're Welcome.

        FYI: plug in "images for solar batch heaters" to web.

        Comment


        • #5
          First you normally would not ever use the load port of a charge controller. All power comes from the battery term post.

          Secondly no way do you have enough power to heat 30L of water with 125 watts of power.
          MSEE, PE

          Comment


          • #6
            Originally posted by Sunking View Post
            First you normally would not ever use the load port of a charge controller. All power comes from the battery term post.

            Secondly no way do you have enough power to heat 30L of water with 125 watts of power.
            Sunking;

            Hi.

            I might have overlooked that but as I am taking on an average of 9A on a very good day, this is England, I thought why not use this spare energy to heat some water up.

            If you put it that way (125W) then you are correct as most 12V water thermostats are in the region of 150W but I am pretty sure I could find one at 100W.

            To your first comment, my charge controller has got a load side to it which can be switched on once voltage has reached a certain point. This is off-course to protect the battery from overcharging, so I thought any spare juice will come from this load point from the charge controller.

            I might stair away from this concept now (Water thermostat) and go for similar to what you have suggested.

            I'll be using some water bottles with some garden drip hose to collect heat and transfer it to the water. Along with this will be a water pump to pump water (circulate existing water on tank and hose circuit) in to the tank once temperature has dropped bellow say 20C and stop at 30C as example.

            Many thanks for your suggestion and eye opener.

            Regards,
            Albert

            Comment


            • #7
              Originally posted by albertc30 View Post
              Sunking;

              To your first comment, my charge controller has got a load side to it which can be switched on once voltage has reached a certain point. This is off-course to protect the battery from overcharging, so I thought any spare juice will come from this load point from the charge controller.
              Albert that is what is called a DUMP LOAD. A place to dump unused solar power after the battery is charged up. In that case you would need at least a 100 watt 12 volt heater. Even though you have 125 watts of panel, in England it will never generate 125 watts so you can get away with 100 watt element if they make them. If not a 150 watt element with the understanding by doing so the actual power will be below 100 watts. A panel is a current source, and if operated into a lower resistance will significantly lower power. Thus you want to use a lower power element to make the most power usable.
              MSEE, PE

              Comment


              • #8
                Originally posted by Sunking View Post
                Albert that is what is called a DUMP LOAD. A place to dump unused solar power after the battery is charged up. In that case you would need at least a 100 watt 12 volt heater. Even though you have 125 watts of panel, in England it will never generate 125 watts so you can get away with 100 watt element if they make them. If not a 150 watt element with the understanding by doing so the actual power will be below 100 watts. A panel is a current source, and if operated into a lower resistance will significantly lower power. Thus you want to use a lower power element to make the most power usable.
                Just came in from work today to find my 22ah deep cycle battery has swallow up.

                It's not even 8 months old.

                I wonder what had happened to it? To much charge? Can't be surely!

                I mean, the charge controller should stop charging it once it's fully charged and dump whatever power I'm getting from the panels right?

                Or this is the case if I DO have a load connected to this dump load on my charge controller?

                Many thanks for your input.

                Regards,
                Albert.

                Comment


                • #9
                  Originally posted by albertc30 View Post
                  Just came in from work today to find my 22ah deep cycle battery has swallow up.

                  It's not even 8 months old.

                  I wonder what had happened to it? To much charge? Can't be surely!

                  I mean, the charge controller should stop charging it once it's fully charged and dump whatever power I'm getting from the panels right?

                  Or this is the case if I DO have a load connected to this dump load on my charge controller?

                  Many thanks for your input.

                  Regards,
                  Albert.
                  My guess is that 22Ah battery was too small for the amount of charging you were sending it. Even an AGM type battery shouldn't be charged faster than C/4 and if you were putting in 9amps that calculates to a C/2.4 which is way too fast.

                  I think we have gotten off track on what your system is. Beside the 100w and 25w panels what is the model of your charge controller and your battery. Next what is your daily watt hour load?

                  Comment


                  • #10
                    Originally posted by SunEagle View Post
                    My guess is that 22Ah battery was too small for the amount of charging you were sending it. Even an AGM type battery shouldn't be charged faster than C/4 and if you were putting in 9amps that calculates to a C/2.4 which is way too fast.

                    I think we have gotten off track on what your system is. Beside the 100w and 25w panels what is the model of your charge controller and your battery. Next what is your daily watt hour load?
                    Hi.

                    Apologies for the sidetrack.

                    My charge controller is an mppt 20A but sadly, accordingly to youtube, I have got a fake MPPT 20A.

                    The battery is a 22ah TPower sticker on it at £31.99. No more information on it. I guess you get what you pay for.

                    I thought that the charge controller would charge the battery at a steady pace and never overcharge it.

                    Regarding the load, perhaps that is what I went wrong with it.

                    There's only 8 X 1W LED lights in the shed with a PIR flood light of 10W. This is hardly all used for about 30 minutes per day, if that.

                    Many thanks for all the input.

                    Regards,
                    Albert

                    Comment


                    • #11
                      Originally posted by albertc30 View Post
                      Hi.

                      Apologies for the sidetrack.

                      My charge controller is an mppt 20A but sadly, accordingly to youtube, I have got a fake MPPT 20A.

                      The battery is a 22ah TPower sticker on it at £31.99. No more information on it. I guess you get what you pay for.

                      I thought that the charge controller would charge the battery at a steady pace and never overcharge it.

                      Regarding the load, perhaps that is what I went wrong with it.

                      There's only 8 X 1W LED lights in the shed with a PIR flood light of 10W. This is hardly all used for about 30 minutes per day, if that.

                      Many thanks for all the input.


                      Regards,
                      Albert
                      That 22Ah battery can safely provide about 53 watt hours a day which sounds like you are using maybe 18 watt hours (I doubled the time to 60 minutes just for good measure) which is less then the 53.

                      So it probably comes down to the suspect MPPT controller as either not going into "float" mode or still the possibility that in "absorb" mode it is putting to many amps to fast into that battery.

                      Comment


                      • #12
                        Originally posted by SunEagle View Post
                        That 22Ah battery can safely provide about 53 watt hours a day which sounds like you are using maybe 18 watt hours (I doubled the time to 60 minutes just for good measure) which is less then the 53.

                        So it probably comes down to the suspect MPPT controller as either not going into "float" mode or still the possibility that in "absorb" mode it is putting to many amps to fast into that battery.
                        I mean, I don't have much to run in the shed.

                        Soon there'll be a 12V light socket that might run a small car 12V air pump (rarely but I do have the push bike that needs air in tyres so often), and an USB port for mobile phone charging.

                        I will have a water 12V pump circulating water from 100mtr of 4mm inner diameter to keep water luck warm to 30C.

                        This pump will be on/of (<20C On, =30C Off). This should take a bit of the battery power and perhaps give it a nice charge/discharge cycle.

                        Another thing I though was to have my extra 20W flood light which is not connected as it was way too powerful and at 20W would be taking too much power (1.66A) so I decided to go with a 10W one, was t have it connected to the load side of the controller.

                        What controller would you advice to buy and replace my existing one?

                        Many thanks for all the input.

                        Regards,
                        Albert

                        Comment


                        • #13
                          Hi.

                          Just seen the new Tracer1215BN at around £55.00.

                          Quite some cost and would this suffice?

                          Being a 10A and I am wondering if I would ever exceed this with my current setup.

                          Again, I cannot thank you enough for all your input.

                          Regards,
                          Albert

                          Comment


                          • #14
                            Originally posted by albertc30 View Post
                            Hi.

                            Just seen the new Tracer1215BN at around £55.00.

                            Quite some cost and would this suffice?

                            Being a 10A and I am wondering if I would ever exceed this with my current setup.

                            Again, I cannot thank you enough for all your input.

                            Regards,
                            Albert
                            If you go back to the beginning of this thread you were talking about adding a heating element or dump load. I don't believe you will need or [U]can[/U] power a heating element if you lock yourself into a small MPPT charge controller. More than likely you will realize you need more panel wattage and that usually means a higher amp rated charge controller and battery.

                            Before you think about the CC or get a new battery, I would take a hard look at your "true" loads. Will it just be those 18watt of lights and that water pump or do you still want to go with a water heater.

                            Building a solar battery system is not easily expandable because you can't just add batteries and panels later. Once you start increasing one item all of the hardware may need to be replaced. Even solar panels should all be the same type and wattage or at least Vmp and Imp ratings within 5% of each other. Mixing small wattage with large wattage panels doesn't work.

                            Comment


                            • #15
                              Hi.

                              Again apologies for the slight deviation from my first post.

                              I no longer will run my water heater element as it will never run at full power. Still I believe it would be sufficient enough to heat the water to luck warm at 30C.

                              Again, given your advice, I might just decommission my 25W panel as I am going to use a different method to heat up the water.

                              The side of the roof where this panel is, I'll use it to heat up the water through the use of water bottles, 4mm ID drip tube and a small 12V brush-less water pump.

                              This pump will be on/off accordingly to the water temp i.e <20C pump on and at =30C pump off.

                              Maybe in the future, I could have some power tools like cordless drills batteries being charged up.

                              My current charge controller is a 20A MPPT (YouTube video shows it as a con and not really an MPPT).

                              So, as I am with a 100W panel I could possibly do with a 10A charge controller.

                              I had all calculations done about 9 months ago when I first started this solar power shed project and this is how I got to a 22ah battery with a total 30% discharge I think.

                              Much appreciated for your input.

                              Regards,
                              Albert

                              Comment

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