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  • double check my small shelter solar

    I have a saferoom/storm shelter that I going to light solely on 12v led and I want to run a few ham radios. At most current needed is 30 amps. Here is my current list and how I'm going to install it.

    Two Suniva 310W Solar Panel wired in series to produce around 90 volts. Need highter voltage because im running 200 feet to the controller and don't want to get huge and expensive with the wiring. 10 gauge should be plenty because it's at 9 amps

    A Outback Power FLEXmax FM60 MPPT Charge Controller because of the high voltage and stepping it down to 12v..

    Two Trojan L-16H type, 6V-435AH wired for 12v

    Also can add another pannel in series to make 140 volts if more charge is needed


    So this is my very first experience and I wanted to ask if I'm missing something?

    Thanks

  • #2
    30A load will be really tough on those batteries and PV. Unless it's very intermittent.
    Can you PV produce 200% of your daily consumption in the few sun hours ?
    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
      Originally posted by Mike90250 View Post
      Can you PV produce 200% of your daily consumption in the few sun hours ?
      And even fewer than normal sun hours in the immediate aftermath of the storm or whatever!
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

      Comment


      • #4
        Originally posted by Mike90250 View Post
        30A load will be really tough on those batteries and PV. Unless it's very intermittent.
        Can you PV produce 200% of your daily consumption in the few sun hours ?
        I'm probably be closer to 30 amps and run for no more than 8 hours.. are you thinking not enough battery? Maybe a should only use two pannels.. my math is fuzzy

        Comment


        • #5
          Originally posted by Racing4funn View Post
          I'm probably be closer to 30 amps and run for no more than 8 hours.. are you thinking not enough battery? Maybe a should only use two pannels.. my math is fuzzy
          To provide 30A at 12V for 8 hours amounts to 240 amp hours (AH), and 2880 watts. To avoid killing your battery the first time you use the shelter you should plan to draw that power from no smaller than a 480AH battery bank.
          If you want this to be sustainable for days or weeks, plan on using a 1200AH battery bank instead.
          And you will need a panel wattage of roughly 4000W divided by the number of sun hours (not daylight hours) you get at the worst time of year.
          So probably an absolute minimum of 2000W of panel.
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

          Comment


          • #6
            Hold the bus guys. He is talking ham radio and only draws 30 amps when keyed up to rag chew, and that is SSB and average current is 1/4 or around 8 amps 30 on voice peaks. I take a take a pair of T-105's in the field for contest just charged up at home and can talk for 2 or 3 days without a charge and still not go below 50%. He has 2 times that capacity. Point here is Contest day the radio gets hammered with a lot of use. Just the nature of the application makes it low duty cycle. Even with an 8 hour day you are talking less than 1 hour at 30 amps. No Problem.

            My system is a 250 watt panel and a pair of Concorde batteries today of slightly less capacity and there is no way I can over work them in a day if I tried. If anything he has way too much power.

            73's

            KF5LJW
            MSEE, PE

            Comment


            • #7
              Originally posted by Sunking View Post
              Hold the bus guys. He is talking ham radio and only draws 30 amps when keyed up to rag chew, and that is SSB and average current is 1/4 or around 8 amps 30 on voice peaks. I take a take a pair of T-105's in the field for contest just charged up at home and can talk for 2 or 3 days without a charge and still not go below 50%. He has 2 times that capacity. Point here is Contest day the radio gets hammered with a lot of use. Just the nature of the application makes it low duty cycle. Even with an 8 hour day you are talking less than 1 hour at 30 amps. No Problem.

              My system is a 250 watt panel and a pair of Concorde batteries today of slightly less capacity and there is no way I can over work them in a day if I tried. If anything he has way too much power.

              73's

              KF5LJW
              Awe yes.. you at contest are working way harder than I will be. I thought I was very conservative on my numbers but would also like to charge small devices and if reasonable a laptop as well.

              Comment


              • #8
                Originally posted by Racing4funn View Post
                Awe yes.. you at contest are working way harder than I will be. I thought I was very conservative on my numbers but would also like to charge small devices and if reasonable a laptop as well.
                Man no problem, you got a lot of extra power to burn. But it does beg the question why us solar for your ham shack? Granted I have it, but everything is free except the batteries, and it has only been used once. My Astron DC Power supply floats the batteries, so the solar is never called upon to ever be used except when power was out for a couple of days and my shack is not on the house genny. Not even needed for a two day Contest.
                MSEE, PE

                Comment


                • #9
                  Originally posted by Sunking View Post
                  it does beg the question why us solar for your ham shack?
                  Mostly because I want too and looking forward to the solar education. My shelter is well built and underground. There is no power and 12 volts can meet all my needs.. I want power from the betteries no matter what's going on outside..

                  Comment


                  • #10
                    Can someone help me decide to use two of the above listed panels or three? I can't decide. What happens when I haven't used any power in weeks and the batteries are topped off? The controler bleeds off the power from the panels?

                    Comment


                    • #11
                      Originally posted by Racing4funn View Post
                      Can someone help me decide to use two of the above listed panels or three? I can't decide. What happens when I haven't used any power in weeks and the batteries are topped off? The controler bleeds off the power from the panels?
                      Not necessary. The nature of solar PV panels is that if you do not take current from them the power is just not generated in the first place.
                      Kind of like the question of what happens to all the power when I run the generator with no loads plugged in.
                      The sun heats the panel up slightly more without the current flow to carry 15% of the incoming energy away.
                      SunnyBoy 3000 US, 18 BP Solar 175B panels.

                      Comment


                      • #12
                        Originally posted by Racing4funn View Post
                        Mostly because I want too and looking forward to the solar education. My shelter is well built and underground. There is no power and 12 volts can meet all my needs.. I want power from the betteries no matter what's going on outside..
                        Hopefully the area where you will be putting your batteries is vented. Also you will need a generator to keep those batteries happy. Solar will not produce enough amps to EQ them so you need either grid power or generator power.

                        Comment


                        • #13
                          Originally posted by SunEagle View Post
                          Hopefully the area where you will be putting your batteries is vented. Also you will need a generator to keep those batteries happy. Solar will not produce enough amps to EQ them so you need either grid power or generator power.
                          I'm using two 6v batteries in series so explain why they wouldnt be equalized? Guess I don't understand and yes they are vented and in a completely separate area than people will be

                          Comment


                          • #14
                            Originally posted by Racing4funn View Post
                            I'm using two 6v batteries in series so explain why they wouldnt be equalized? Guess I don't understand and yes they are vented and in a completely separate area than people will be
                            Under most conditions you will get enough sunlight from you panels to properly charge those batteries. The problem is that there will be times when you will not get enough sunlight and therefore will need another source of power to recharge the batteries and if necessary get them to an EQ level.

                            Anyone that has an off grid system needs to have a backup power source to properly maintain their batteries. Without that gen set you run the risk of not keeping those batteries healthy and shorten their life.

                            Comment


                            • #15
                              Originally posted by SunEagle View Post
                              Under most conditions you will get enough sunlight from you panels to properly charge those batteries. The problem is that there will be times when you will not get enough sunlight and therefore will need another source of power to recharge the batteries and if necessary get them to an EQ level.

                              Anyone that has an off grid system needs to have a backup power source to properly maintain their batteries. Without that gen set you run the risk of not keeping those batteries healthy and shorten their life.
                              Correct me is I'm wrong.. more than likely I won't be using these batteries but for 5 or so hours a week.. more than enough power and time from the panels to complete a charge. In fact there will be more wasted power because the batteries are complete and they aren't being used than needed panel power for charging. It's just the nature of not hanging out in an underground room.. I've been thinking about way I can limit wast. Meaning what to do with panel power when batteries are charged and my tinny system isn't worth the expense of grid tie. I got a golfcart I could charge..

                              My usage of 30 amps for 8 hours listed in the first post was way over exaggerated heavyiest case scenario.

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