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  • Newb with questions... Grounding & Charge controller amperage

    Thanks Mike and SunEagle for trying to help me out. I appreciate the guidance and the time to help point me in the right direction. Are you guys on any other forums that are dedicated to solar energy or alternative energy? If so.. PM me. I'd like to get more input but I'm pretty well done here. Thanks again.
    Last edited by Mr4btTahoe; 01-27-2017, 06:56 PM.

  • #2
    STOP buying stuff

    Don't even think of using a 12V system unless you are in a vehicle. The wiring losses are too great, and the chance of flames shooting out from parts is high.

    you should be looking at 24V at least, and to do it right, for a house backup, 48V. Much easier to wire with #6 wire instead of with that expensive 2/O cable

    From the design stickies (you read those right?) what are the loads (in watt hours) ?
    Then you size the batteries then you size the PV

    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 Mr4btTahoe
      Well... I have bulk 2/0 cable already... so no cost. Got several hundred feet given to me.

      Like I said originally, I will not be taxing the inverter at all. Mainly a couple hundred watts at a time based on my Kill-a-watt meter. As far as "emergency back-up" goes... the only thing that would be powered in this case would be our deep freeze which pulls 95 watts running... surges to 850-900 when the compressor kicks on (main reason I went overkill with the inverter).

      I looked into higher voltage systems but the components are too far out of my budget at this point. If I want to change it up later, I can use this system to power my shed, etc.. so no real waste.

      From everything I've read... 2/0 is more then enough for the battery bank... 6awg is what is suggested for the amperage at 12v from the panels for the length of run with less then 3% power loss (and 12' of 6/2 isn't very costly).

      Everything is well within spec... (other then the charge controller which is what I asked about).. so please explain yourself a bit better. I could understand dropping 10-20k if I was wanting to power something significant... but I'm not. So why is 12v an issue?
      Simple. 12volt DC requires larger wire due to the higher amps being run through it. (Amps = Watts / Voltage)

      What can also cause a problem is that due to the distances between the battery and load, it is easy to get below that minimum voltage level due to voltage drop losses.

      Also even if you use large AWG wire you must use the proper crimping tool to attach the proper terminal. Any additional resistance incurred due to poor crimping or lose termination adds to the problem by introducing heat which can create weak point in the wiring system and failures.

      Using higher voltage system allows you to use smaller wire, longer distances, and safer terminations.

      Oh last thing. If you plan on powering a building from 2 different power sources you still are required to have a single equipment grounding point or at least a continuous ground path connecting all of the equipment to the same ground. Having two different ground points can result in an electrical shock due to the potential difference between them.

      Comment


      • #4
        Originally posted by Mr4btTahoe

        I'm aware of the high amperage in a 12v system. It's what I'm used to (was big into high end car audio for a good while... so running multiple 2/0 runs.. multiple alternators... amplifiers pulling 500+ amps at full tilt... I'm used to that.) So why is it more or less dangerous when the components are sized accordingly?

        The distance between the battery bank and load (inverter) will be less then 6' (which is what is suggested by the manufacturer of the inverter). They also suggest using 4/0 (which is why I'm going to be running pairs of 2/0.. larger conductor area then 4/0).

        As for the tools... I have it all as I'm used to working with 2/0 cable. I have the cable cutters... the crimpers... the ends. I have soldered ends also and heat shrink of proper size.

        Using a higher voltage system means I can't use basic 12v (easily accessible) appliances/chargers if something were to happen to the inverter. It also triples the price for a quality pure sine inverter.

        Now as far as the grounding... it seems unsafe to me to bond the ground rods over such a distance as the wire would have to go under the house.. meaning if lightning were to strike, the power would go under the full length of the house and depending on how hot that wire gets... could it be a potential fire hazard? Tying the ground rods together isn't a big deal.. just didn't seem safe to me and I didn't know how not tying them together could cause an issue with all devices/sources being separate.
        Going with 12volt equipment is a decision to be made by the customer. If that is what you want then that is what you use.

        You asked why you shouldn't use 12volt and I supplied the answers. It can be unsafe if not wired and fused properly. And it does increase the losses in the wires which adds to the cost of running the system as well as potentially shortening the life of the components due to the extra heat generated.

        I understand not wanting to spend any more money then you have to but if you keep increasing your system then you will run into a wall due to the limitations of 12volt systems and the maximum amount of panel wattage they can handle. But again it is your money and your right to spend it as you feel.

        Oh for additional thought there are places that can get many days of no or little sunlight. Batteries will fail and unless you have some other power source you will be in the dark. But again that is a decision you have to make.

        Comment


        • #5
          Originally posted by Mr4btTahoe
          *cough* "I'm calling this system off-grid as it is completely separate from the grid power in my home. I'm setting this up to power the addition to my house and for emergency use to keep from running the generator during power outages, etc."
          If a building has two sources of power going into it unless there is a clear way of keeping the two completely separate it doesn't matter what you call it. The NEC still requires a single ground.

          Also the fire department will need to be able to de-energize all power being supplied to protect their people so I hope your "off grid" system (which is installed on your home) complies with their rules.

          Comment


          • #6
            Originally posted by Mr4btTahoe
            it will not be connected to any house wiring.

            Originally posted by Mr4btTahoe
            It will have its own outlets and fixtures wired to the inverter and the inverter alone. It won't supply power through the main panel in the house, etc... Wiring will come out of the inverter... to a few outlets and light fixtures that are not connected to the wiring in the house. How is that not "off grid"? If it isn't attached to the grid in any form... it is "off grid" is it not?
            It is off grid. BUT it sounds like it is still wired into the wiring in the house (light fixtures and outlets), thus the building has two power sources.

            It also has more requirements than single ground and a properly labeled disconnect.
            You need to follow code and get a permit for this system.
            Just because something is off grid doesn't mean you don't have to follow code.
            OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

            Comment


            • #7
              Originally posted by Mr4btTahoe

              It will have a main disconnect. it will not be connected to any house wiring. It is just attached to the same building. I don't know how else one could make it any more separate. It will have its own outlets and fixtures wired to the inverter and the inverter alone. It won't supply power through the main panel in the house, etc... Wiring will come out of the inverter... to a few outlets and light fixtures that are not connected to the wiring in the house. How is that not "off grid"? If it isn't attached to the grid in any form... it is "off grid" is it not?
              I really don't want to argue the point but if there is an outlet from the solar/battery/inverter system in one room that can power something in another room (using an extension cord) that puts it in close contact with it's ground you have created a potential danger between the two systems. If there was a fire wall and no way to run power (even temporarily) between the two sections of the home then you would be ok.

              Just because you plan on not running power from one system into the area of the other system is not enough to keep it safe. There needs to be a physical barrier that will protect anyone that does not know where the power comes from and the dangers of two sources that have separate grounding systems. The idea is to protect the electrically untrained person from doing something that can hurt them.
              Last edited by SunEagle; 01-25-2017, 04:46 PM.

              Comment


              • #8
                Originally posted by Mr4btTahoe

                It's a 2kw inverter from Xantrex. ProWatt SW2000. Suggested cable size is 4/0 (not 4awg) in the manual. 4awg wouldn't handle the surge amperage of the inverter (3k rated surge) without serious voltage drop.
                I knew that already. So a 2000 watt 12 volt Inverter requires a minimum 12 volt 1600 AH battery. A 12 volt 1600 AH battery requires a a 2000 watt panel system with two very expensive 80 amp Charge Controllers. You have no clue what you are doing.

                Sorry but I will not help you anymore. I will not help a child play with a loaded gun waiting to discover what the trigger does while looking down the barrel or pointing it at his Mom. I am done here. FWIW a 2/0 AWH in free air is good for 300 Amps. You do not size the cable for surge. Good bye.
                MSEE, PE

                Comment


                • #9
                  Originally posted by Mr4btTahoe
                  So.. it will NOT be wired to the house wiring. I will be installing my own outlets behind the items I want to power which will be fed from a panel that only connects to the inverter. Wiring will come from the inverter.. to outlets (almost as if I were plugging an extension cord into the inverted directly) but installed permanently to the home with separate boxes and 12awg romex. Make more sense?

                  Thanks bud.
                  That IS house wiring. You will have plugs in the wall that look just like regular plugs with wires built into the house...
                  OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                  Comment


                  • #10
                    Originally posted by Mr4btTahoe
                    With that being said... maybe you can answer some questions because a few things the other guy said were contradictory. At first he said I didn't need to bond the grounding rods..
                    Wrong dead wrong. I never said any such thing. You just do not understand what you are being told. You are in way over your head. That is why I am out and will not be responsible. What you are trying to do takes at least 2-year technical school and 5 years apprenticeship to grasp. There is no way you can do this on your own. So when things go wrong, sue the Forum, I wash my hands of it.

                    Both Moderators have already told you the same thing. Butch and other pros can try to teach you and take responsibility. I do not want any part of it. FWIW with the charge controller you have just turned your 600 watt panels into 400 watts. Just enough for two of your six batteries and a 500 watt inverter. One more thing. That Inverter you have cannot be used in a home in any code compliant manner. It is a MOBILE INVERTER made for RV's and Trucks, that is why it has GFCI receptacles for Plug and Cord. An Inverter made for a house or home does not have Receptacles, they have Hardwire terminals approved and listed for residential wiring applications. They usually come with Built in Battery Chargers to charge batteries from AC power or Generator support.

                    I suggest you go to Northern AZ Wind and Sun Forum. There you will be told what you want to hear and feel good about it. Hell they we even offer to sell you everything you need to burn your house down. Sorry I tried to help you, but you are to far above your head and cannot understand what is being told to you. learn.

                    Just remember this simple fact as it is easy to understand. Anything you take off grid is going to cost you 10 times more than buying it from the power company for the rest of your life in battery cost alone, not including anything else. For you even more because what you have now will not work and compatible for any growth. Like Mike told you, quit buying stuff. .

                    So Jeff and Butch have at it if you dare.
                    Last edited by Sunking; 01-25-2017, 08:39 PM.
                    MSEE, PE

                    Comment


                    • #11
                      Originally posted by Mr4btTahoe
                      WTF... you deleted your response. I asked you a question on post #14. You responded. First word you typed was No. Don't give me that BS.
                      Like I said, you do not even understand what you have been told.

                      You said specifically and I quote you
                      As far as a floating system goes... would the ground rod placed near the array still need to be bonded to the home's AC ground rod (being as the systems are 100% separate from each other)
                      My answer was:

                      No, the systems cannot be isolated and must share a common GES. Run A down conductor to a ground rod, dig a trench, and bond to the AC service ground. You did not understand the answer. When it came apparent you were in deep popo, I deleted everything because I knew I was wasting my time and want no responsibility.

                      MSEE, PE

                      Comment


                      • #12
                        Don't be a fool. The only UL listing is UL 458 approved for Marine use. Try reading the documents like this one. Very clearly states the intended purpose. You see nothing of a fixed location. For your home requires UL 1741. Try reading this and look at the Selection Guide. Xantrex does not make a Inverter for residential. they sold that off to Schneider Electric. Residential Inverters do not have receptacles, hard wire only.

                        Be sure to read this bit you will hate.

                        This guide includes a specifications table for available battery-based, sine-wave inverters that are listed to the Underwriters Laboratories 1741 standard and commonly used in residential applications (2 to 8 kW). The compiled data is from manufacturers and their specifications sheets.
                        We are done here, and you are on your own.
                        Last edited by Sunking; 01-25-2017, 10:34 PM.
                        MSEE, PE

                        Comment


                        • #13
                          Originally posted by Mr4btTahoe
                          ......Also... the inverter uses a built in GFCI outlet (not hardwired). I'm curious how the GFCI trips... the case ground?
                          A GFCI works by measuring the amps in both the Hot and Neutral wires, more than 2-3mA difference, it trips off line, Current sneaked off somewhere, maybe through a person.

                          Starting off with large parallel 12v batteries (even when made from 6v batteries) is the beginning of a long, expensive journey, Sunking pulled his posts when he felt he could be liable for your repeated misunderstanding, and will now not give you advice that you repeatedly mis-interpret because you have an inflexible mindset about how to do this,

                          That's the long answer. The short answer is, you may have had fun with high power car stereos at 12V, but it does not scale to household wiring.

                          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


                          • #14
                            GFCI requires NO GROUND OF ANY KIND. That is why they were invented, and used in homes with 2-wire AC receptacles. Code allows them to be used in Grand Fathered homes so electricians do not have to completely rewire a home just to add a receptacle. The GFCI in those cases do not have anything terminated to the Ground Pin. operation. As code evolved in the 70's GFCI today must be used in any WET LOCATION's like bathrooms, kitchens, laundry, and outdoors. You can spot a MOBILE INVERTER a mile away, If you see GFCI receptacles on the INVERTER, it is a MOBILE INVERTER and not approved for premises wiring applications. Inspectors, Code, and most importantly you Home Owners Insurance carrier does not give a damn what the manufacture says their product can be used for. Without UL1741 certification it will not fly.

                            Can you get away with it if no permits or inspections are required? Sure you can. But if something happens like a fire, death, or injury comes along, the FD and Insurance Inspector is going to notice a HACK job and you will be held fully liable for all damages and injury. Ignorance is not a defense.

                            As Mike said GFCI doe snot use any ground. It monitors the current in both current carrying conductors. If there is more than 100 ma difference, means current is is going some place it should not, and thus operates. If is for idiots who place a radio, TV, electric razor, or hair dryer next to a tub or sink with butter fingers. Or for use in Mobile applications. A Mobile Inverter has the chassis bonded to the grounded circuit conductor, and thus cannot be used in any premises wiring. Installing Car Toys does not qualify you to do any electrical work. Sory that is just the way it is. There is to much to know and takes years to get your head wrapped around the fundamentals. I wish you luck, but we cannot walk you through it. You do not even know enough to ask questions or understand what you are being told.

                            Keep in mind Forms like this are sales tools. Fortunately many pros here are not vested in the owner or any particular energy technology. Some like Butch and Jflorey are, and want to sell you something even if not from themselves. The owner of this forum is in Australia and has no vested interest in the USA. Folks come here to get straight honest answers. Otherwise like I said you can go to Northern AZ Wind & Sun Forum where there are a lot os salesman who will try to help amd sell you something. That is the way it works.

                            Good Luck
                            MSEE, PE

                            Comment


                            • #15
                              I'm not an installer I live off grid, understand electricity and have cut a few corners (blasphemy) but nothing that can be dangerous.


                              But scaling a car stereo up to a 120V house install, is beyond the scope of the limited advice we can provide over the internet. When you solder power wires together
                              you only think you are doing a good thing, but you are creating a fire hazard, when there is a short, the soldered connection often melts and falls apart before a fuse blows, Then you have molten metal working though the battery case........ Or a DC arc burning, waiting for some hydrogen.
                              If an educated person comes asking a well formed question, we can answer that, Adding another ground rod to the other side of your house is not a simple task, it needs to be bonded with large solid wire or braid, to the other ground rod. How that's done is beyond what the volunteers here are able to instruct you.
                              We can show you how to do the math to double check a solar salesman's payback numbers, or what size battery for a certain size load, But how to install household electrical grounds is not simple
                              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

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