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oh no another confused newbie, solar data sheets what to use to spec the system

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  • oh no another confused newbie, solar data sheets what to use to spec the system

    hello all, I am planning on moving to Hawaii and the lot i have purchased is far from utilities. I have been working on a system but am completely lost with these panel data sheets. i am an industrial maintenance tech and most of what i deal with is 480 3 phase power. these sheets have open circuit, short circuit bla bla bla. I realize it is somehow figured on the curve of full sun, no sun, load and no load. my basic question is what set of voltage numbers and amp numbers should i use to configure wiring and fuses and components.

    secondary question is i would like to run 2 charge controllers mainly for redundancy since if i have a failure i would rather have 1/2 a working system until it can be repaired. I am wondering if i will loose any efficiency in the panels since the charge controllers are supposed to optimize the panels. I have a small drawing of my plans so far if someone sees a problem please let me know. right now i am using the highest output numbers on the data sheets.
    plan.png

  • #2
    It is hard to tell how you wired those 200 watt panels to each CC. If you provide the panel spec (Voc, Vmp & Imp) we can help you determine if they are optimally wired for those CC's

    Next, if you have 4 x 6V 240Ah batteries wired in series it creates a 24V 240Ah battery system. If you wire two sets of 4 in parallel you get a 24V 480Ah battery system not a 1920Ah system.

    The 6V ratings adds up if wired in series and the 240 Ah will stay the same. The 240 Ah adds in parallel wired circuits and the 24V voltage stays the same.

    Comment


    • #3
      sorry for the battery part 1920 is what i need. the panels i am looking at are 200watt, VOC 44.56,VMP 36.7, ISC 5.99, IMP 5.45 VOC temp co%0.33.
      I was planning to wire 2 in series, 2 series in parallel. thats part of my confusion they are listed a 24v panels with circuit data at 44.56. if i am reading things here i would need a set of 100V 30A charge controllers.

      Comment


      • #4
        Nice.
        So here are my questions
        How/where panels be mounted, rooftop, pole mount, ground array ?
        How far from the building housing the charge controller and batteries?
        Does the battery building have ventilation for battery fumes
        Have you considered a 48V forklift battery?
        Will your planned inverter work with a Generator as a Source for AC & charging in bad weather, or do you need a separate battery charger ?

        And MOST IMPORTANT :
        have you worked up what 24 hours of load, would be in both Watt Hours and Peak Watts ? Motor Starting surge must be accounted for, fridge motor, water pump, sewage pump
        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


        • #5
          The confusing thing about PV panel specs is their output is non-linear so is hard to describe with simple numbers. Their voltage is pretty constant throughout the power curve, but when the current drops to zero (you disconnect them or "open-circuit") the voltage goes up dramatically. They are also quite temperature sensitive with the voltage going up the colder they are. So..... the Voc number is the highest voltage they might give off which is important when making sure the input voltage range of the charge controller isn't exceeded. And the Vmp spec is the highest power you can ideally expect the panel to produce which divided by your battery voltage will give you the highest current level that the charge controller needs to handle.
          BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

          Comment


          • #6
            Mike i am looking at roof mount and since i need to build the house a 4/12 pitch roof would give me the 14 degree angle for the location, the system will be attached to the house so the wiring run from panels to controls is 35-40 feet and yes the shed will have open floor vents as well as roof vents. I have considered 48V batteries, we just converted 2 lifts to lithium ion and i am watching the performance of those, right now i have very affordable access to fork lift batteries but do not know the availability i will have for them in Hawaii. i have a 110v 30 amp generator and when i get down to inverters will pick one with internal charging abilities. I have and calculating the morning with coffee pot running, fridge door opening and closing causing it to start, water pump from the catchment system running for sink and such, and light or 2 with TV i have a surge wattage of 1800.00 and a 24 hour daily figure of 7200 watts usage a day, I also factored in the temp and reduced panel output by 20% and figured on 5 sun hours a day when the actual data is 6, and anticipate 7640 watts a day from the array. that was one of my original questions because i do not want to configure the system that will drop the efficiency.

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            • #7
              Thank you solarix that explanation helps.

              Comment


              • #8
                My pleasure.... (I try to "help the pods")
                BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

                Comment


                • #9
                  Originally posted by h2ocean View Post
                  Mike i am looking at roof mount and since i need to build the house a 4/12 pitch roof would give me the 14 degree angle for the location, the system will be attached to the house so the wiring run from panels to controls is 35-40 feet and yes the shed will have open floor vents as well as roof vents. I have considered 48V batteries, we just converted 2 lifts to lithium ion and i am watching the performance of those, right now i have very affordable access to fork lift batteries but do not know the availability i will have for them in Hawaii.
                  Stick with conventional lead acid flooded batteries. Vary stable, known tech, known behaviors.

                  Hawaii Grid is very particular about what gear connects, if you know there is no chance for grid connection, be free with choice of gear.



                  i have a 110v 30 amp generator and when i get down to inverters will pick one with internal charging abilities.
                  Many inverters need 240VAC for generator functions, some can manage with 120V or you can use an AutoTransformer to match the voltage and balance the loads



                  I have and calculating the morning with coffee pot running, fridge door opening and closing causing it to start, water pump from the catchment system running for sink and such, and light or 2 with TV i have a surge wattage of 1800.00 and a 24 hour daily figure of 7200 watts usage a day, I also factored in the temp and reduced panel output by 20% and figured on 5 sun hours a day when the actual data is 6, and anticipate 7640 watts a day from the array. that was one of my original questions because i do not want to configure the system that will drop the efficiency.
                  With 7.2Kwh usage, you are going to want close to a 4 or 5KW of PV. And your coffee is going to have to wait till the sun is on the panels.

                  And with needing to store for 3 or 4 cloudy days, you will need 48V system, not 24v


                  With off-grid, you need to allow for Bulk charge time (90 min), Absorb (120min min) and anything left over, ends up as float. You will never be able to fully utilize your panels, there will always be unused power on sunny days. Cloudy days, you rely on being over-paneled to not have to run your generator, even haze or scattered cloudy will drop your harvest.

                  Also with whatever gear you get, you need to consider programming, logging, monitoring and firmware updates, and what additional equipment is needed for that


                  BatteryWattHourCapacity.jpg
                  Last edited by Mike90250; 03-26-2018, 10:54 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

                  Comment


                  • #10
                    Originally posted by h2ocean View Post
                    sorry for the battery part 1920 is what i need. the panels i am looking at are 200watt, VOC 44.56,VMP 36.7, ISC 5.99, IMP 5.45 VOC temp co%0.33.
                    I was planning to wire 2 in series, 2 series in parallel. thats part of my confusion they are listed a 24v panels with circuit data at 44.56. if i am reading things here i would need a set of 100V 30A charge controllers.
                    You are correct that wiring 4 panels 2S2P will yield a Vmp ~ 73.4V and Imp ~ 10.9amps. If the CC was a PWM type it would provide 10.9amp of charging I think those are MPPT type which will convert the 800 watts to ~ 33amps for a 24volt battery system.

                    If you need a 24V 1920Ah battery system you will need to use different batteries. The Rolls "L-16" that Mike shows are rated 6V 546Ah. A string of 4 will get you 24V 546Ah battery system. Two of those strings wired in parallel will yield a 24V 1092Ah battery system. Adding a third string should boost you to 1638Ah but then you run the risk of unequal charging and discharging of those batteries which tend to shorten their life. Going to 4 strings of 4 will yield a 24V 2148Ah battery system but increases the chance of killing your batteries much sooner than expected.

                    To maybe clear up the confusion about 24V panels, That is a short description just like a 12V panel is a "battery type". Most 24V panels will provide high Vmp levels like the 200w one you have mentioned.
                    Last edited by SunEagle; 03-26-2018, 12:08 PM.

                    Comment


                    • #11
                      thanks mike the chart is very helpful, can you tell me how to calculate the Wh, in series do the amp hours stay the same G2C 90Ah but the watt hours increase?(my 1st reply) and are dual charge controllers a bad thing? by the way i am old enough to remember what a percolator is, so i can have my coffee early just with propane.
                      For all who are helping thanks and i am not stuck on any particular battery voltage so if 48V is best than that is fine.

                      Comment


                      • #12
                        Sun that was my question on the dual panel and charge controller wiring, do 2 charge controllers on 2 strings eliminate the problem you pointed out by adding the 3rd string to the system you described? if I was a millionaire and could do 4 strings you have laid out it would be 1 controller to each set of 4S2P or does all that go out the window when they are hooked to the inverter and become 4 parallel strings?

                        Comment


                        • #13
                          Originally posted by h2ocean View Post
                          thanks mike the chart is very helpful, can you tell me how to calculate the Wh, in series do the amp hours stay the same G2C 90Ah but the watt hours increase?(my 1st reply) and are dual charge controllers a bad thing? by the way i am old enough to remember what a percolator is, so i can have my coffee early just with propane.
                          For all who are helping thanks and i am not stuck on any particular battery voltage so if 48V is best than that is fine.
                          The bigger the battery system is the higher voltage should be used.

                          Sometimes having a "duplicate" component is a life saver but it adds to the complexity of the solar/battery system.

                          A battery stays "happy" when it receives charging amps between C/8 and C/12 where C = Ah rating. So for a panel wattage of say 60 amps you can use a battery system between 480Ah - 720Ah. If you build a big battery system and then lose half of the charging amps because of a CC equipment failure your batteries will now be grossly undercharged and no longer be "happy".

                          Comment


                          • #14
                            Originally posted by h2ocean View Post
                            Sun that was my question on the dual panel and charge controller wiring, do 2 charge controllers on 2 strings eliminate the problem you pointed out by adding the 3rd string to the system you described? if I was a millionaire and could do 4 strings you have laid out it would be 1 controller to each set of 4S2P or does all that go out the window when they are hooked to the inverter and become 4 parallel strings?
                            IMO it would be best to use a quality CC that can take an input voltage ~ 150V. The amp rating would be sized based on the total panel wattage divided by the battery system voltage. In your case going with an 80amp MPPT type CC will require a panel wattage around 3800W and a 48V battery system at around 800Ah.

                            Comment


                            • #15
                              Originally posted by h2ocean View Post
                              thanks mike the chart is very helpful, can you tell me how to calculate the Wh, in series do the amp hours stay the same G2C 90Ah but the watt hours increase?(my 1st reply) and are dual charge controllers a bad thing? by the way i am old enough to remember what a percolator is, so i can have my coffee early just with propane.
                              For all who are helping thanks and i am not stuck on any particular battery voltage so if 48V is best than that is fine.
                              Watt hours A battery is spec'd for 12V @ 90A total, consumed over 20 hours. That would be a steady 4.5A drain, about what a tail light bulb draws.
                              thus
                              12V x 90A = 1080watt hours (the 90A has the hours built into it) or 12v x 4.5A x 20h = 1080 watt hours

                              ----

                              Devices in Series (batteries or PV panels) : Voltage adds up, amps are constant 12V, 3.6A | 24V,3.6A and so on
                              Devices in Parallel Voltage is constant, amps add up 12V, 3.6A | 12V, 7.2A

                              ------

                              Looking at the chart, you can see it's easy to get to 48V , 9120 watt hours of battery, and pretty darn cheap with golf cart batteries. You can do it with 24V, but needs parallel strings.
                              For your loads, it seems like 2 parallel strings of cheap golf cart batteries @ 48V 18,240wh



                              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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