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  • #16
    Originally posted by plantian View Post
    Could you recommend a better controller setup for just 12volts?
    I can't, 1500 watts is too much for a 12 volt system and you have 2 of those inverters.......

    It looks like your components aren't sized to work together. The best advice I can give you is to start over at the beginning. Figure out how many watts us use in a day and multiply it by 5. That's the size your bank should be. Size your solar panels and inverter at roughly 1/10th the watts of your battery bank AND pick a system voltage that keeps the amps below 90.

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    • #17
      I wrote up some estimates.

      Estimated daily watts at ~600 watt hours, please see attached pdf. (laptop, router, modem, credit card reader, printer, wireless phone system... all only on during business hours, some turned off after usage during business hours)

      Here are some calculations based on this sticky -- Battery Design -- http://www.solarpaneltalk.com/showth...Battery-Design

      Using CA, La Jolla, because there is no San Diego, but its more inland I'm going to estimate 4.5 sun hours.

      http://www.solardirect.com/pv/system...sun-hours.html

      Panel Watts = (Daily Watt Hours * Fudge Factor) / Sun Hours

      200 = (600 * 1.5) / 4.5

      Battery Amp Hours = [5 x Daily Watt Hours] / Battery Voltage

      250 = (5 * 600) / 12

      MPPT Amps = Panel Wattage / Battery Voltage

      16.7 = 200 / 12

      Let's say that my estimation is a magnitude of 2 off and really we are using 1200 Watts. So...

      Panel Watts = 400 = (1200 * 1.5) / 4.5

      Battery Amp Hours = 500 = (5 * 1200) / 12

      MPPT Amps = 33.4 = 400 / 12


      If I reduce the batteries to 4 and have both controllers wired up to 2 x 150watt panels each (8.38 A) I should have about 34 amps coming into the batteries right?

      If my inverter watt rating is too high that just means they are too big for the batteries and would drain them if something ever pulled that much power but it shouldn't hurt anything if my devices are using way less than that right ?

      Do my numbers and calculations above make sense?

      Thanks for your time.
      Attached Files

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      • #18
        Originally posted by plantian View Post
        Estimated daily watts at ~600 watt hours, please see attached pdf. (laptop, router, modem, credit card reader, printer, wireless phone system... all only on during business hours, some turned off after usage during business hours)
        ok, that's doable. No idea why you have 3000 watts of inverters for that but whatever.


        Originally posted by plantian View Post
        Here are some calculations based on this sticky -- Battery Design -- http://www.solarpaneltalk.com/showth...Battery-Design
        Awesome.


        Originally posted by plantian View Post
        Using CA, La Jolla, because there is no San Diego, but its more inland I'm going to estimate 4.5 sun hours.
        Wow that's a lot of winter sun.


        Originally posted by plantian View Post
        If I reduce the batteries to 4 and have both controllers wired up to 2 x 150watt panels each (8.38 A) I should have about 34 amps coming into the batteries right?
        No your charge controllers are MPPT you should expect to see more current than the Imp. Not that you'll see these numbers real world but 600w/12v=50amps.


        Originally posted by plantian View Post
        If my inverter watt rating is too high that just means they are too big for the batteries and would drain them if something ever pulled that much power...
        My concern is the amount of current that inverter can draw, it's what 100 amps, more?


        Originally posted by plantian View Post
        ...but it shouldn't hurt anything if my devices are using way less than that right ?
        Sure, it'll be inefficient.

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        • #19
          Okay, well I'm still trying to move forward on this. I feel that converting everything to 24volt or 48volt and buying new inverters and charge controller might be a good idea at some point. I just struggle with the fact that would be over $1000 which is more than the panels. So I'm still sticking with the equipment I have until I hit a major roadblock.

          So moving forward with the 12volt system now I'm trying to determine how to setup the grounding. If I run each set of 150Watt panels into a combiner box that then feeds into a blue sky controller, so 2 panels --> 1 combiner box (2 15amp breakers) --> 1 charge controller, then how should I wire up the combiner box with breakers. So assuming I will need to ground all equipment casing with a grounding rod. Does the grounding bar + breakers require that the SYSTEM be grounded for the breakers to work or is that depending on the inverters or something else? (ie. the negative line is grounded) I've read a bunch of posts on it and everyone says throughout that grounding is really hard but there doesn't seem to be a consistent solution. Sometimes it seems to depend on the internal wiring of the inverters themselves. What do I need to look for to determine how or if I need to ground my system?

          Thanks.

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          • #20
            Originally posted by Bucho View Post
            It's both, you can't put more than 30amps into a 30amp charge controller. Decent controllers also won't convert more volts into amps than they can handle so you can over panel them and *shrug* some power will get wasted at noon on a nice day.
            Yes and no. You cannot put more than 30A into a 30A PWM CC unless it does not actually regulate the output current but just shuts down when it overheats. In the latter case you could put 40A in and get 40A out for awhile.....

            Many CC manufacturers put limits on the amount by which you can "overpanel" the input.
            Once they are into the Absorb stage where they are regulating the average output voltage, the current limit is set by the battery, not the CC.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

            Comment


            • #21
              A grounding rod is only useful protection for static electricity. Your circuit breakers/fuses are to protect against overloads and short circuits. The normal scheme is to attach all the metal equipment casing, boxes, etc to your ground wire and to attach ("bond") your ground to your neutral in the breaker panel.

              Then if something goes wrong causing the hot to touch one of those metal casings etc there will be a short and your breaker will trip instead of said metal casing remaining hot indefinitely. Your grounding rod has nothing to do with that BUT it is essential that your ground is bonded to your neutral.

              Here's where the trouble starts, your inverter might have the ground and neutral bonded already in which case it's a no no to do it again. You might be able to bond ground and neutral OR your inverter might not have a true neutral in which case said bonding will break the inverter.

              You may want to start a separate thread just to resolve said dilemma and accept that follow your inverters manual will be a common response.

              Comment


              • #22
                Originally posted by plantian View Post
                Point 1: How many 100 watt panels can I connect to this controller?Is this right: 4 panels x 5.29A = ~21A because 21A < 25A which is the controller's max.100W 12V Panel (5.29A/short circuit 5.75A):http://www.amazon.com/RENOGY-Monocry...dp/B009Z6CW7O/2000E Controller:http://www.amazon.com/Blue-Sky-Energ...dp/B007S1N3F8/Point 2: Now if I want to have 2 of these controllers, the 2000E, connected to the same set of batteries will they conflict because they don't support a master/slave configuration?Point 3: What is the difference between the 2000E and the 3000i?It seems like they'd both only support 4 of the 100Watt panels above.3000i Controller:http://www.amazon.com/Solar-Boost-30...dp/B00LCCDH5K/Thanks for your time,- Ian
                Why on earth do you want to use expensive low voltage battery panels. You can buy a 300 watt GT panel for the same price you could a 100 watt battery panel. Secondly why 12 volts? You are planning the most expensive, ineffective, and inefficient system you could possible design.
                MSEE, PE

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                • #23
                  Originally posted by Sunking View Post
                  Secondly why 12 volts? You are planning the most expensive, ineffective, and inefficient system you could possible design.
                  The threads already been over this, he already owns a bunch of mismatched gear that he ought to sell on craigslist but is committed to using.



                  Originally posted by Sunking View Post
                  Why on earth do you want to use expensive low voltage battery panels. You can buy a 300 watt GT panel for the same price you could a 100 watt battery panel.
                  His charge controllers can only take 30v.

                  Comment


                  • #24
                    Fine I give up. What charge controllers, inverters and panels do you guys recommend? Please provide me a few links if you could. I need 600 watts of panels. The way the system is wired I need 2 inverters.

                    Comment


                    • #25
                      Originally posted by plantian View Post
                      The way the system is wired I need 2 inverters.
                      Could you explain how that works?

                      Also you mentioned existing solar panels. How many panels and what's wrong with them other than being 10 years old, are they warranted to put out at least 80% for 20 maybe 25 years?

                      If you do need to completely replace your panels instead of the panels that your looking at renogy also has a polycrystalline 300w panel. Even with the freight shipping across the country to me of $285.52 I could get 600w of those for nearly a hundred less than what your looking at doing. I don't know where you are but if you can find a place you can pick up the panels and skip the shipping you could potentially save enough for a charge controller.

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                      • #26
                        One set of the panels is 10 years old and the other set is 15 years old. They are less than 450 watts I think and one is damaged via golf ball. The area is very shaded so a new skeleton structure was built farther from the batteries to hold the panels. Doesn't seem worth it to go through all the trouble to use the old panels. I was going to just collect them and use whatever is still working for something else.

                        There is a retail kiosk type thing that the batteries are stored at and it has an inverter with a power strip that a few things plug into. The old panels are on top of that and the Charge controllers are there.

                        Also there is DC wiring run from the batteries into another shed 40 ft through conduit under the ground where another inverter is connected that runs various things. I'm not sure why AC wasn't converted at the sales kiosk and then run underground but that's how its setup. Maybe my late father thought it would be safer to just have a low voltage dc line than ac. Or more likely it was a lot cheaper to get 2 inverters than put in proper AC wiring: ac disconnect, ac breaker, ac plugs, etc. Maybe something else? Its worked since 2000 that way but I'm sure its not the best.

                        The mttp charge controllers I have looked at all are $500 or more. Here is one I looked at http://www.amazon.com/Morningstar-Tr.../dp/B0052UIPIC.

                        The panels I was looking at are $820 for 600 watts with free shipping which is about $1.37 per watt. That shipping is through amazon prime. I can't find the 300 watt panels on Amazon. Shipping the 300watt 24v renogy panels to me in California from renogy's online store costs 285.52, which with the price of 529.98 is about $1.36 per watt.

                        I asked an electrician to install the 4 new panels and he told me he doesn't do jobs that small and doesn't know anyone that would and that I should probably just do it myself.

                        Comment


                        • #27
                          Welcome, and I'm sorry this is getting to be such a mess. Trying to "grow" or re-use parts of an old system is tough. At least you are moving the panels out of the shade !

                          Are you totally locked into 12V (any gear that runs on 12V that you are needing to keep?) or can you move to 24V ?

                          At least you are mostly doing Daytime loads, and not all night.

                          Regarding the remote building, it's much better to invert near the batteries and run 120VAC the distance to the other building.

                          With your loads, I'd suggest a pure sine inverter, and with it, you can use standard AC grounding techniques. Mod wave inverters can't be used with standard Neutral bonded to Ground. (corrected from 3rd wire safety ground)
                          Last edited by Mike90250; 08-15-2015, 03:21 AM.
                          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

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                          • #28
                            Originally posted by Mike90250 View Post
                            Mod wave inverters can't be used with a 3rd wire safety ground.
                            Not quite true. You can and should use a 3rd wire safety ground. You just must not ever connect it to the neutral conductor.
                            If you need to use equipment that connects the neutral to its chassis or case, then you do not want to use a mod square inverter.
                            SunnyBoy 3000 US, 18 BP Solar 175B panels.

                            Comment


                            • #29
                              Originally posted by plantian View Post
                              The panels I was looking at are $820 for 600 watts with free shipping which is about $1.37 per watt. That shipping is through amazon prime. I can't find the 300 watt panels on Amazon. Shipping the 300watt 24v renogy panels to me in California from renogy's online store costs 285.52, which with the price of 529.98 is about $1.36 per watt.
                              It looks to me like the panels you linked to are a touch more than that but not that much. Sunking's a pro and I'm not sure that he's not the most familiar with how residential shipping can effect the prices. Like I was saying before the significant savings from those larger panels would come from picking them up yourself. Whether you were to take a pickup to Ontario CA yourself or search for a closer retailer.

                              Originally posted by plantian View Post
                              The mttp charge controllers I have looked at all are $500 or more. Here is one I looked at http://www.amazon.com/Morningstar-Tr.../dp/B0052UIPIC.
                              The point of replacing your hardware would be to take your system to 24v. That would reduce the parallel connections in your battery bank and reduce your voltage drop. It also means that you could use something like a single midnight kid 30a which is around $300.

                              P.S. A couple more questions, what is that wire that goes to your second inverter? Also what are those inverters, are they square wave?

                              Comment


                              • #30
                                The 40 feet 12 volt DC wires to the inverter will kill you with voltage drop. Ask a technician to look at the wires there to see if it can carry the AC current. I think it should. You can just use one big enough inverter for both places. If you can use 24 volt battery bank, The Tracer 40 amps MPPT charge controller can support up to 1000 watts panels which only cost a little over $200 US on amazon.

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