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  • 1st Time Solar Setup. Advise Needed

    Hello everybody. I could really use some help setting up a solar system.
    ​​​​​​
    I'm stuck on a ranch off grid for the time due to "shelter in place." I have been home with my 4 year old. We use a generator here and it's burning through a lot of gas. I'm on a tight budget and have been trying to piece together a simple solar system to use when it's sunny out.

    What I have so far is 5, 170 watt BP solar. Solar panels:
    Peak power (pmax) 170
    Production Tolerance of pmax +5 -3%
    Voltage @ (pmax) 35.6
    Current @ (pmax) 4.8 A
    Open Circuit Voltage 44.3 V
    Short Circuit Current 5.2 A
    Maximum Series Fuse 15 A
    Limiting Reverse Current (lr) 5.2 A

    1, 100ah deep cycle blue Powermall battery
    LFP12100
    Cycle use 14.5-14.9V
    Stand by use 13.50 13.80V
    Initial Current less than 30 A

    An old 1500 watt 12V inverter
    Xpower by Xantrex

    And I ordered an mppt charge controller which I'm already regretting. Powmr 60 amp. That should be delivered Friday.

    What I had hoped to do was power about 100 watt load while the sun is shining. Tv, Direct TV box, & a Wii U.

    In the near future I was hoping to score 1 more of these panels, another battery, and a 24 volt inverter.

    I would be greatfull if anyone has any input on what I can do with what I have, what else I need. As far as wiring & fuses, and what I can do with it. Plus any advice on expanding to 24 volt.

    Thanks in advance. I'm a totally new to all this, so any advice would be really helpful.

  • #2
    Hello Josh00 and welcome to Solar Panel Talk

    Well I see a couple of problems with the equipment your are putting together.

    With 5 x 170watt panels you can get about 850 watts of generation. With an MPPT type CC that can get you about 70 amps of charging.

    The basic formula for charging a FLA type battery is to have amps to equal 10% of your battery system Ah rating. So with 70amps that would mean a 700Ah battery system.

    So two things that will hurt you is first your 60amp MPPT charger which could mean you have too many panel watts but if you do not face them all in the same direction you may be able to work with them.

    The second item is that 100Ah battery. It is way too small for your panel wattage and will never provide the watt hours you are looking to get when the sun isn't shining.

    I would ask you to look at your loads and determine the number of watt hours you need to burn each day. Remember you will not get sunlight every day so don't rely on the solar panels to generate much of anything on cloudy days.

    Once you determine your daily watt hour usage you can then calculate your battery size and then your panel wattage and CC rating.

    If you go with your existing equipment you will more than likely burn up that 100Ah battery which will get you no power if it should fail.

    Comment


    • #3
      Hi SunEagle thank you for your time, I the appreciate the advice.

      So, to use all the panels I would need another CC and 6 more of those $200 batteries? Dang!

      I tested with a kill-a-watt meter. I'm using about 70 watts for the entertainment center, and another 35 for the video game console.

      ​​​​​Is what I'd like to do for now workable with what I have? Should I just start out by using only 2 panels? Would I still need a 2nd battery?

      Can you suggest what's my most economical path forward?

      Also if I'm going to spend a bunch. What's my best bet for making the best use of these panels?

      Comment


      • #4
        Originally posted by Josh00 View Post
        Hi SunEagle thank you for your time, I the appreciate the advice.

        So, to use all the panels I would need another CC and 6 more of those $200 batteries? Dang!

        I tested with a kill-a-watt meter. I'm using about 70 watts for the entertainment center, and another 35 for the video game console.

        ​​​​​Is what I'd like to do for now workable with what I have? Should I just start out by using only 2 panels? Would I still need a 2nd battery?

        Can you suggest what's my most economical path forward?

        Also if I'm going to spend a bunch. What's my best bet for making the best use of these panels?
        With your current single 100Ah battery you can use 2 of those panels to properly charge it.

        The problem with that one 100Ah battery is that is can provide at best 300 watt hours a day (100ah x 12v x 25% = 300wh) which does not sound like enough for you to run those loads very long. If you use more than 25% of the battery capacity you will greatly shorten the battery life. This may be ok with you but you will be replacing it much sooner then expected.

        As for using more of those panels... wiring more than 2 in parallel will result in an early death for one or more of them. You may be better off getting 6v golf cart batteries. They are usually rated for more than 200Ah each and two of them in series gets you a 12V 200Ah+ system for a lot less then that AGM type of battery.

        Comment


        • #5
          You can minimize the amount of energy needed and the size of your battery plant,
          by getting a 12VDC powered TV and other small stuff. This will eliminate all the losses
          of converting up to 120VAC and back down inside the devices, plus there will be no
          idle current of a larger inverter running even when little is turned on. Days the panels
          will essentially directly power the loads, reducing wearing out your batteries. Nights
          will be the only time power is taken directly from the batteries. good luck, Bruce Roe

          Comment


          • #6
            Originally posted by bcroe View Post
            You can minimize the amount of energy needed and the size of your battery plant,
            by getting a 12VDC powered TV and other small stuff. This will eliminate all the losses
            of converting up to 120VAC and back down inside the devices, plus there will be no
            idle current of a larger inverter running even when little is turned on. Days the panels
            will essentially directly power the loads, reducing wearing out your batteries. Nights
            will be the only time power is taken directly from the batteries. good luck, Bruce Roe
            While I agree with some of your logic there may be some days the OP gets no sunlight which will put all of the drain on the battery system. Of course if the OP follows load shed procedure and turn off all electronics when the clouds are out they may get by with that system.

            Comment


            • #7
              Originally posted by SunEagle View Post

              While I agree with some of your logic there may be some days the OP gets no sunlight which will put all of the drain on the battery system. Of course if the OP follows load shed procedure and turn off all electronics when the clouds are out they may get by with that system.
              Right, and any battery system needs a generator. But if the basic load is small enough,
              one of those quiet and fuel saving inverter generators might still drastically reduce
              gasoline consumption. Bruce Roe

              Comment


              • #8
                The only thing I would add is that IF that is indeed a LFP battery and it is capable of charging at 30 Amps then you can use some of the panels up to that rating.You might not have to buy as many batteries because LFP batteries are more efficient and can be discharged more than 50% without damage.

                Comment

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