Building a 48-volt Solar System . . .

billbaty
billbaty Registered Users Posts: 3
in Solar Beginners Corner #1
Hi,

I need to get my solar system up and running but every time I try, I just don't know where or how to get started. I have found various wiring diagrams and photos of systems up and running but I still don't know where to begin. So I am wondering if there is instructions somewhere that begins with Step 1, Step 2 and so on that I could follow?

My Components:

MX60 PV MPPT Charge Controller
MidNite Solar E-Panel
3648 VFX Inverter
2 - 175 watt solar panels
NMNPV3 Combiner
8 - UB 6 volt Batteries

I have the e-panel, charge controller and inverter mounted in an outdoor cabinet but with no other connections between them. There is room for the batteries in a lower compartment (also not yet connected). I have a pergola next to the cabinet where I can mount the panels.

Eventually I would like to produce all of our electrical power but for now I feature just connecting a couple of household circuits to get a feel for it all. I am not interested in a grid-tie setup.

All the best,

Bill Baty
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Comments

  • ButchDeal
    ButchDeal Solar Expert Posts: 35 ✭
    #2
    Re: Building a 48-volt Solar System . . .
    billbaty wrote: »
    I have the e-panel, charge controller and inverter mounted in an outdoor cabinet but with no other connections between them. There is room for the batteries in a lower compartment (also not yet connected). I have a pergola next to the cabinet where I can mount the panels.

    I would suggest you look at the OutBack documentation and forums. They have quite a bit on setting this up. I would also recommend not putting the batteries in the same cabinet below the electronics. This does not meet code in many locations and is pretty risky should one of them off gas, unless the lower compartment is separately sealed off and vented.
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  • billbaty
    billbaty Registered Users Posts: 3
    #3
    Re: Building a 48-volt Solar System . . .

    Wow! I originally posted there and the only 2 replies suggested that I try here!

    I have looked at online documentation for both Outback and midNite solar, heck, I even have the printed owner's manuals. They contain no procedure recommendations. There are schematics maps that detail every possible connection but no mention about what wire one should actually connect first (then second) or what the final step would be. I am only assuming that I have all the components I need. The batteries ARE in a separate compartment and vented away from the electronics.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Building a 48-volt Solar System . . .

    The important thing is to not turn anything on until it is all wired up and checked. Twice.

    In terms of activation the procedure is to connect the batteries to charge controller output first, then connect the PV input. At that point you should be able to check the charging function. Then you can activate the inverter and check its operation. AC loads get turned on last.

    If you like you can follow the same order of operations for installing the wiring. Just be sure the last connection you make is the one that will make power available to whatever circuit you are working on (i.e. connect battery terminals last after all wiring is run to charge controller output and fuse/breaker is installed).
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
    Re: Building a 48-volt Solar System . . .

    Hi Bill,

    Welcome to the Forum.

    OK, but to help us catch up with what you want to do with the system, a few questions;

    1. What is the manufacturer and model number of the solar panels that you have?
    2. I assume that batteries that you NOW HAVE are U S Battery(?). What is the manufacturer of the batteries that you have, and model #?

    3. Are you connected to the power Grid?
    4. If you are on the grid, is the grid power reliable?

    Generally, the cost of grid power is much lower cost than off-grid power. There are exceptions to this, but this is usually true.

    You have an e-panel, so the manual for that will help a lot regarding how to wire the system, and what to use in the way of breakers, etc.

    As was mentioned on the MN Forum, designing these power systems usually start with the power loads that the system must supply, the general time of day for these loads (ie, will the battery need to supply then, or perhaps directly from PV), the peak load on the system, etc.

    You have the Inverter, and MX-60. so you have started planning, or perhaps you have guessed a bit. The manuals that you should have for these two Outback products have a lot of information and diagrams for the system.

    For others, I suggested that Bill come here, from the MN Forum, due to breadth, and depth knowledge of experience, plus the wealth of information and traffic here.

    Also, there are many Threads here demonstrating a lot about the process of power system design ... will look for some examples ...

    Am concerned that you have some system parts, and BATTERIES. The batteries may need charging soon. Please let us know the info on exactly what these batteries are, for better advice. Later, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #6
    Re: Building a 48-volt Solar System . . .

    I would also have concerns that (2) 175w panels would likely not be sufficient charging for (est) 215ah of battery at 48v.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Building a 48-volt Solar System . . .
    jcheil wrote: »
    I would also have concerns that (2) 175w panels would likely not be sufficient charging for (est) 215ah of battery at 48v.

    You are correct. The PV would only be able to maintain the batteries with no load on, not recharge them.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #8
    Re: Building a 48-volt Solar System . . .

    Bill,

    Here is one Thread on this Forum for your perusal:
    http://forum.solar-electric.com/showthread.php?20828-Molokai-Off-grid-system-design-help

    There are many threads here, so perhaps you can do a bit of poking around on your own ... every application, and therefore, system is a bit different from others, but the general rules will still hold.

    It is more difficult to describe a cookbook How To process than it is to answer more specific questions, so, if possible, ask away.

    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • billbaty
    billbaty Registered Users Posts: 3
    #9
    Re: Building a 48-volt Solar System . . .

    Hello Everyone,

    Thanks for all the helpful replies.

    My updated list of solar electrical components:

    MX60 PV MPPT Charge Controller
    MidNite Solar E-Panel
    3648 VFX Inverter
    2 - 170 watt solar panels, BP Solar model# SX 17013
    NMNPV3 Combiner
    8 - UB 6 volt AGM Batteries 205 amp hr

    Hopefully it all will provide more power than to just keep the batteries charged. If not, I am prepared to add to the system. In fact I already anticipated adding on. But all this can be decided and worked on later. Right now I would just like to get it all wired up where I can get a feel about how it all works and become familiar with it all, even if it will only trickle charge the battery bank.

    I'll read the Thread: http://forum.solar-electric.com/show...em-design-help , as well as other threads and just keep on until I get it working. In the meantime I will attach the panels to the pergola and begin one wire at a time.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Building a 48-volt Solar System . . .

    Look at it like this:

    Two 170 Watt panels is 340 Watts. About 77% efficiency out of the controller on a 48 Volt system gives you (340 * 0.77 / 48) 5.4 Amps peak current. That's a 2.6% peak charge rate or roughly half the minimum manufacturers recommend, exclusive of loads. There is simply no way that is going to charge those batteries.

    Another POV:

    340 Watts * 4 hours equivalent good sun * 0.52 over-all system efficiency = 707 Watt hours AC per day. Not much.

    Without running the VFX's built-in charger from a generator this system is doomed to failure. You should actually have about 1250 Watts of panel for normal use of that battery capacity (25% DOD or about 2.4 kW hours).
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  • South Africa
    South Africa Solar Expert Posts: 295 ✭✭✭
    #11
    Re: Building a 48-volt Solar System . . .

    What the rest said.

    Here as a thought though, for I was where you are, just started with 20w panels, to get the 'feeling', just connect 4 batteries for now, knowing that the panels may not be enough.

    For you can get quite far, if I got the right panels, with lots of potential adding on when you are satisfied it works:
    Attachment not found.
    5kVA Victron Multiplus II, 5.2kW array, 14kWh DIYLifepo4 bank, all grid-tied.


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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #12
    Re: Building a 48-volt Solar System . . .

    Hi Bill,

    Thank you very much for the added information on your system.

    AGM batteries generally have a low self-discharge rate, and can sit for a few months with NO loads on them, when at reasonable temperatures.

    Did not see the manufacturer's name or exact model number for the batteries, just make sure to check on their recommended charge voltages, and the way that they recommend ending the Absorption stage. Setting the chargers to the EXACT voltages recommended is very important on Gel and AGM batteries.

    With Sealed batteries, like AGMs, it is very important to use a Battery Temperature Sensor on each charge source -- the Charge Controller and the Inverter. You might need the Outback Mate, to customize the charge settings for your batteries. Others will tell you this for certain.

    Did your e-panel come with circuit breakers for your Charge Controller (CC)? Do you have breakers for the PV combiner? Usually the e-panel comes with a large breaker for the inverter.

    One of the first things that you may want to do, is to set up a way to charge your batteries with the correct voltage settings, AND you probably should not place any loads on the batteries until you are able to recharge them.

    Thanks, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Building a 48-volt Solar System . . .
    Vic wrote: »
    With Sealed batteries, like AGMs, it is very important to use a Battery Temperature Sensor on each charge source -- the Charge Controller and the Inverter. You might need the Outback Mate, to customize the charge settings for your batteries. Others will tell you this for certain.

    If you have an Outback inverter you must have a MATE to program it with. Trying to run with the default settings is suicidal.
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