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  • Getting more bang per buck!

    Hello everyone! My first post in this forum!

    Please forgive my ignorance and if I use the wrong terminology.

    I tend to ask a lot of dumb questions but im afraid its the way my brain works...


    My current setup is as follows

    600w solar panels
    TriStar 45amp mppt controller
    Studer innotec XTM 24v 2400w inverter
    Small 24v battery bank ( used solely for emergency lighting and keeping central heating pumps running )

    I did also have a little 600w grid tie inverter, a soladin 600, but this has been disonnected and will not be used again due to illegal grid feeding ( ahem...)

    This set up had been running quite nicely for about 6 years or so but now the soladin has been disconnected I'm having to pay for my electricity during the sunny days.

    I'm not an expert but there must be some way I can directly utilise my current kit to get / use free electricity without grid feeding and not cycling the small battery bank?

    There is a white paper from studer that shows how its possible by cycling the batteries but I didn't want to go down that route.

    There is an option within the xtm not to grid feed and I thought if I connected the soladin the protected side of the xtm would I then be able to make use of the free electricity but not feed the grid? However I'm slightly nervous as the soladin, as far as I know, doesn't have the ability to reduce output in relation to the load and I have no idea if its pumping out all that electricity itll cause problems. I'm assuming it has to go so where? ( see? A hatrick of dumb questions, ignorance and wrong terminology!)

    Anyway, anybody have any thoughts on how I can get my free electricity back without incurring the wrath of the electricity company?

    All the best

    Dave

  • #2

    $1745
    That can get you 1500 watts during the day. Hopefully there is a better answer than this for you from one of the experts here.
    Last edited by SunEagle; 05-03-2016, 01:02 PM. Reason: removed advertisement link

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    • #3
      Originally posted by nomadh View Post
      $1745
      That can get you 1500 watts during the day. Hopefully there is a better answer than this for you from one of the experts here.
      Thanks nomadh. I had a look at these before, however utilising this as a solution means I'd need to spend more money!

      Now I am not opposed to spending a little more but the best part of 2k is way too much.
      Last edited by SunEagle; 05-03-2016, 01:02 PM. Reason: removed advertisement link

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      • #4
        Originally posted by Galician Dave View Post
        I'm not an expert but there must be some way I can directly utilise my current kit to get / use free electricity without grid feeding and not cycling the small battery bank?
        Use the power without cycling the battery bank. If you use power only when the system is generating, and you keep your usage to under what the system is putting out (which for you is about 400 watts) you won't cycle the batteries. Have two outlets next to each other and switch your small loads during the day, then switch them back at night.

        Alternatively do a legal grid tie system.

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        • #5
          Originally posted by jflorey2 View Post
          Use the power without cycling the battery bank. If you use power only when the system is generating, and you keep your usage to under what the system is putting out (which for you is about 400 watts) you won't cycle the batteries. Have two outlets next to each other and switch your small loads during the day, then switch them back at night.

          Alternatively do a legal grid tie system.
          OK - how would I do that?

          The power would still be coming from the batteries right? Because the flow is from panels, to controller, to batteries to inverter to outlet. That would mean there would still be a draw on the batteries.

          I've used something similar to this before. There is a function within the xtm which allows priotising the renewal power source. You set a buffer on the batteries ( if batts are 27.2v but ≤xxv ) and you use that buffer ( so you still have capacity in an emergency ) the xtm then maintains that buffer and excess is fed into the protected side and supplemented from the grid.

          I want to avoid cycling the batteries in any shape or form. So direct usage of the solar power generated.

          Now, giving it more thought I wonder if I couldn't build something to go between the controller and batterie and then pass that voltage direct to!the inverter when there is a draw? No idea about how feasible that is or if it is even possible?

          Grid tie legally. So after i had a visit from the electric company I did consider this. Unfortunately the regulations, paperwork and the need to employ highly trained and expensive, electric company certified operatives to come in condemn my existing installation, charge for putting in a new one etc etc is just cost prohibitive.

          Plus the spanish are know " taxing the sun". You pay more money in tax to the government for home produced electricity fed into the grid than you do to buy it. Crazy I know but google it I kid you not.

          Comment


          • #6
            If your charge controller is connected to the battery, and the inverter is connected to the battery, any power draw in excess of what the battery needs to stay in the buffer range will flow directly to the inverter. There is some light cycling, but you can consume a lot of daytime power that doesn't actually go into the battery at all.
            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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            • #7
              Originally posted by Galician Dave View Post

              OK - how would I do that?

              The power would still be coming from the batteries right? Because the flow is from panels, to controller, to batteries to inverter to outlet. That would mean there would still be a draw on the batteries.
              The terminals of the batteries are connected to both the inverter and the charge controller, thus the terminal is a DC bus....
              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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              • #8
                Won't solve you general power needs but if you have any loads that could be ran as "opportunity loads" then you could get a dump load controller and harvest the excess power after the batteries are charged.

                WWW

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                • #9
                  Originally posted by Galician Dave View Post

                  OK - how would I do that?

                  The power would still be coming from the batteries right? Because the flow is from panels, to controller, to batteries to inverter to outlet. That would mean there would still be a draw on the batteries.

                  I've used something similar to this before. There is a function within the xtm which allows priotising the renewal power source. You set a buffer on the batteries ( if batts are 27.2v but ≤xxv ) and you use that buffer ( so you still have capacity in an emergency ) the xtm then maintains that buffer and excess is fed into the protected side and supplemented from the grid.

                  I want to avoid cycling the batteries in any shape or form. So direct usage of the solar power generated.

                  Now, giving it more thought I wonder if I couldn't build something to go between the controller and batterie and then pass that voltage direct to!the inverter when there is a draw? No idea about how feasible that is or if it is even possible?

                  Grid tie legally. So after i had a visit from the electric company I did consider this. Unfortunately the regulations, paperwork and the need to employ highly trained and expensive, electric company certified operatives to come in condemn my existing installation, charge for putting in a new one etc etc is just cost prohibitive.

                  Plus the spanish are know " taxing the sun". You pay more money in tax to the government for home produced electricity fed into the grid than you do to buy it. Crazy I know but google it I kid you not.
                  Unfortunately most charge controllers require a battery connection to start up and then a connection to the panels.

                  You might be able to use a fully charged battery during the day to start up the controller and then use all of the power from the panels to the inverter. But if the sunlight is not consistent then your inverter will draw power from the battery. It will get cycled a little or a lot depending on the sun and your loads.

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                  • #10
                    Originally posted by Galician Dave View Post
                    The power would still be coming from the batteries right? Because the flow is from panels, to controller, to batteries to inverter to outlet. That would mean there would still be a draw on the batteries.
                    No. If the batteries are fully charged, and you have an additional 10 amps of solar power available, then your load will draw from the panels rather than the batteries. (With the MPPT controller.) How it works is this:
                    -Load draws 10 amps. Battery voltage begins to droop.
                    -CC detects droop and increases output.
                    -CC then supplies power to load.
                    I want to avoid cycling the batteries in any shape or form. So direct usage of the solar power generated.
                    That's what you will get with the above system. If you don't trust yourself to regulate your usage, then put in a relay that will drop your loads if the voltage ever drops below 13 volts.
                    Now, giving it more thought I wonder if I couldn't build something to go between the controller and batterie and then pass that voltage direct to!the inverter when there is a draw? No idea about how feasible that is or if it is even possible?
                    That's what you will get with the above system.
                    Grid tie legally. So after i had a visit from the electric company I did consider this. Unfortunately the regulations, paperwork and the need to employ highly trained and expensive, electric company certified operatives to come in condemn my existing installation, charge for putting in a new one etc etc is just cost prohibitive.
                    You don't need "highly trained and expensive, electric company certified operatives" to do it. You can do it yourself if you like and then get the required inspections. Or you can get a local company. (And the local companies here certainly do not use "highly trained and expensive, electric company certified operatives.") And if the inspectors "condemn" your existing installation and require changes - they are doing you a favor in the long term. Most inspectors are quite reasonable, and as long as you make a good faith effort to follow the NEC, will be willing to list the changes needed to bring your installation up to code.
                    Plus the spanish are know " taxing the sun". You pay more money in tax to the government for home produced electricity fed into the grid than you do to buy it. Crazy I know but google it I kid you not.
                    Are you in Spain?
                    Last edited by jflorey2; 05-04-2016, 12:18 PM.

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                    • #11
                      Hi everyone, thank you for taking the time to respond and explain things to me. I'm very grateful. So much more to learn!

                      Jflorey2 - yes, I'm located in sunny Spain.

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                      • #12
                        Originally posted by Galician Dave View Post
                        Jflorey2 - yes, I'm located in sunny Spain.
                        Ah, my mistake. Ignore my comments about the NEC in that case.

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                        • #13
                          It seems you want a fairly normal off grid system but with a limiter like mentioned above. If you have the batteries and you want to keep them charged its good to keep them in the circuit for buffering and when a fridge or ac causes a startup surge. Just something extra that stops you from draining the batteries much. Maybe just a <13v buzzer to warn you or just cut the system off.

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