Announcement

Collapse
No announcement yet.

Noob Setup Question

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Noob Setup Question

    Hello,
    We have a small off grid Solar setup for the cabin up north. The cabin has been around since the 40s so we have propane stove and refrigerator. It was decided to stop wasting propane on the lighting a few years ago, so we slowly started putting together a 12v lighting system.

    Last year we had a 18w solar panel and one donated battery with a coleman 7a solar regulator. Which was not enough to keep up with demand. We had 12v incandescent bulbs (7 or 8 amps of load). We also only get 5 to 6 hours of good sun.

    This year a larger 12v solar system was donated consisting of 4 20w panels and we still had the 18w panel. These were all hooked in parallel and I installed a new solar30 regulator.
    http://www.pvcontroller.com/index.ph...d-display.html
    When I hooked the panels up I measured with my voltmeter and saw 23v. Which I thought was high but wasn't sure.
    We also installed fluorescent and LED bulbs so the total load is only 2 to 3 amps with all the lights on now.
    We hooked everything up and it worked great.

    The problem we are having now is the battery seems to be getting overcharged. One went bad right away and I assumed it was just old age. But now another new battery is bad and several of the lights have failed.

    My question is what is wrong with the system? I know the solar30 is a pwm and is supposed to stop charging at 13.6 volts (this is user selectable). The battery is a deep cycle. Should this be just a regular car battery? It is around 70ah sized. Let me know if you need any more information from me.

    Thanks in advance!

  • #2
    Run the calculator in the battery design thread in the off grid forum
    If you input everything correctly this should tell you what is required vs what you have.
    A standard car battery won't last long

    Also describe the wiring lengths from panels to CC etc
    And finally the specs on the panels and battery
    NABCEP certified Technical Sales Professional

    [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

    [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

    [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

    Comment


    • #3
      Total daily load (Watt hours) 300
      Inverter efficiency (use midpoint on efficiency curve) ex 80% enter .8 0.8

      Total daily load (Watt hours including inverter losses) 375
      Maximum load (to inverter) 100




      Lowest daily insolation for area and time of year the system will be used 3.5
      Use PV watts to determine insolation or http://www.gaisma.com/en/
      Amp hour capacity Max charge current FLA Max charge current AGM
      Battery bank @12 V (AH 20% daily DOD) 156.25 19.53 39.06
      Battery bank @24 V (AH 20% daily DOD) 78.13 9.77 19.53
      Battery bank@48V (AH 20% daily DOD) 39.06 4.88 9.77
      Amp @12V Amp @24V Amp@48V
      Panel wattage required PWM controller 214.29 17.9 8.9 4.5
      Panel wattage required MPPT controller 160.71 13.39 6.70 3.35


      Here is what it gave me. Obviously we don't have a inverter. So that .8 modifier could go away correct?

      The Coleman® Solar Battery Charging Kit is ideal for cabins, recreational vehicles, remote power, back-up power, 12 Volt battery charging and more. Solar kit produces up to 18W/1.2 mAh of clean, free power in all weather conditions. Comes with four pre-cut holes for installation, a 12V DC plug, alligator clamps, 12 ft. of wire, 4 stainless steel mounting screws, voltage tester and 7 amp charge controller with Quick Connect technology.•Durable ABS plastic and amorphous solar cells construction
      •Plugs into your vehicle's 12V lighter socket or directly to battery with included connections
      •Works with automobiles, RVs, boats, tractors, ATVs, electric fences, deer feeders, telemetry and more
      •Solar panel works in all daylight conditions, even when cloudy
      •Works in all weather conditions
      •Maintenance-free with easy installation
      •Built-in blocking diode protects battery discharge at night
      •Temperature range: -40° to 176° F
      •Max power output: 18W, 1.2 mAh
      •5 year limited warranty

      This is the original Coleman panel.

      I am not sure the manufacturer of the other panels. They were brand new and seemed to be quality made.

      The battery is a standard 12v deep cycle for use on a trolling motor. like this one. http://www.walmart.com/ip/EverStart-...Q%26A+Exchange

      Another thing I should have mentioned is the cabin does not get used much during the week. So it is usually a load on the weekend and has the rest of the week to charge.

      The highest load would be about 60 watts an hour now.

      Also the wiring from the solar panels to the Charge Controller is about 30' of 12/2 romex.

      Thanks.

      Comment


      • #4
        Ok
        You have about 100 watts of panel if the amperage is about equal
        On all of them you will get about 70
        Watts out of them or about 5 amps to the battery.
        You are also losing a bit on the wiring
        The wires from panel to charge controller should be # 10.
        Assuming that is a 100ah battery you need to double panel amount to give it a decent charge. To get to at least a c/10 rate or 10 amps to the battery.
        Sounds like a deficit charging issue to me.
        If it is over two years old the battery is probably shot.
        NABCEP certified Technical Sales Professional

        [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

        [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

        [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

        Comment


        • #5
          Originally posted by bigguy158 View Post


          Here is what it gave me. Obviously we don't have a inverter. So that .8 modifier could go away correct?
          No way for a MPPT controller 66%, and for PWM controller 50%.

          80% is for grid tied systems, not battery.
          MSEE, PE

          Comment


          • #6
            Originally posted by Sunking View Post
            No way for a MPPT controller 66%, and for PWM controller 50%.

            80% is for grid tied systems, not battery.
            Actually that is inverter efficiency and not controller efficiency.
            He is running everything 12v so no inverter
            NABCEP certified Technical Sales Professional

            [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

            [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

            [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

            Comment


            • #7
              Originally posted by Naptown View Post
              Ok
              You have about 100 watts of panel if the amperage is about equal
              On all of them you will get about 70
              Watts out of them or about 5 amps to the battery.
              You are also losing a bit on the wiring
              The wires from panel to charge controller should be # 10.
              Assuming that is a 100ah battery you need to double panel amount to give it a decent charge. To get to at least a c/10 rate or 10 amps to the battery.
              Sounds like a deficit charging issue to me.
              If it is over two years old the battery is probably shot.
              That is close to what I have seen. The highest instantaneous charge was around 3.8A panel set to 45 degrees on the 45thish parallel. So are you saying we may have over discharged the battery on the weekend?

              This doesn't explain why the fluorescent bulbs burnt out. I am assuming that it was a overvoltage situation. I am wondering with a PWM Charge Controller a undersized battery and a high voltage output from the panels could have wrecked the battery. (The battery was new this year.)

              The other thing is we are not looking to recharge the battery in a single day, or are you saying we have to? We don't use the cabin during the week that much. So if we had a 1500w deficit on the battery at the end of a weekend it would have all week to charge.

              I guess I was hoping for your expert opinions. On what you guys would do/install in this situation.
              Would you put in a MPPT controller?
              What batteries would you install?
              Knowing we don't need a full recharge the next day to we need more solar panels?
              Anything you would do differently?

              Thanks for every ones help.

              Comment


              • #8
                Ok here's the problem with too small a
                Charge and waiting for a week for it to charge. The battery unless immediately recharged fully will begin to sulphate or grow crystals on the plates. This reduces the specific gravity on the battery and gets worse and worse until the battery will no longer hold a charge.
                For battery health you never want to discharge more than 20% daily or 50% occasionally you also want to recharge immediately and fully in one day.
                Your CFL burnout is likely due to low voltage not high.
                NABCEP certified Technical Sales Professional

                [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

                Comment

                Working...
                X