Need Advice "new off grid system"

AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
Hi everyone. What a wealth of information there is on this site. 
I thought I knew a little about solar but after reading here for a while, I would really like some input. 
Im in the process of building a house off grid, and need to get my solar set-up dialed. 
Please would some of you look over what I am thinking and advice and offer some input BEFORE I go buy everything. 
Will be in Colorado at about 9000ft

Here is the list Iv come up with so far 

ME-ARC Remote 

ME-AGS-N Auto Gen Start

ME-BMK Battery Monitor Kit

MS4448PAE Inverter/Charger 

MAGMMP175-30D Breaker 

MNDC125 or 200 DC Disconnect

XANXWMPPT60-150 Charge Controller (Big Enough?) * Update and changed to an ME PT-100 Controller

12x 305W Selivo Solar panels. 3.36kw ( 2 top of pole arrays 6 panels on each)

Battery 24-85-13 48V (GB Industries) 804 AH Capacity 

------

I have a 10KW kubota diesel generator, that ill be using for construction and hope to build that into the system once the house is built. 

For the guys that are experienced what am I missing? 

Appreciate any help, Thanks Andy 




Comments

  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    edited June 2017 #2
    Not sure the Schneider MPPT60-150 is your best choice. I am using it, but in your case it may not be the best. The MPPT60-150 goes into a derated mode at 140V input. Although it isn't harmed by anything until 150V, that makes the upper limit you need to design for at 140V.  At that elevation in Colorado, you will have some very cold temperatures and so you'll need to design allowing for a pretty high Hyper-Voc. I assume those panels are nominal 24V panels (72 cell?), so you will only be able to use two in series for each string. 

    Since your other stuff is Magnum, you should consider the Magnum PT-100. It would tie in nicely to your other Magnum stuff. It can handle input voltage of 200V + the battery voltage, so 248V in your case. That means you can probably go to 3, or maybe even 4 (I'd need to do the math) panels in series. It also can put out 100A, probably making better use of your array. Note that I know nothing about the battery you are planning, so you may have to limit the charge to way under that 100A.

    Steve

    Edit: Holy cow! Those panels are almost 70V Voc! You wouldn't even be able to do two in series with the MPPT60-150. I couldn't find the Voc temp coefficient, but you may be unable to do more than two panels in series even with the PT-100.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    Ok, I found the Voc Temperature Coefficient for those panels. It's -0.262%/deg C. That's actually not too bad. I didn't check my math multiple times, but my first cut indicated that using the PT-100 with a 248V limit, you could run 3 panels in series per string, so four strings. The Hyper Voc wouldn't exceed the limit of the charge controller until you got to -54.47 deg C (-66.05 deg F), which is unlikely even at 10,000 elevation.

    Like I suspected, if you used the MPPT60-150 you would have to run all the panels in parallel, which wouldn't even give you enough voltage at Vmp on the input of the charge controller to give adequate charge to your 48V battery. In addition, you would be carrying almost 60 amps (Imp at STC) from the PV to the charge controller, so you'd need some pretty hefty wire.

    Steve

    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    If Voc is ~70v, that implies all the cells are in series? I think most panels are wired internally as two strings of cells in parallel. As well as complicating external panel wiring chioces to take account of temperature and controller voltage constraints, having all the cells in series means a bit of snow or a bird bomb can pretty much kill the output of the whole panel. With two strings internally, you may still get ~1\2 output.

    At your altitude you should get better production than most of us, but you may still be a bit light on pv for that size of bank. Assuming your expected loads make the bank size right, and that this will be a full time home, I'd add another 6 panel pole. That would give you 18x300=5.4kw/58v charging = 93a. Most of us would get more like 70a in the real world. That would mean a second (or bigger) controller, but IMHO having two controllers may be a good idea anyway. Each controller would be less heavily loaded, and there's some redundancy for when one dies.

    As for what's missing, combiners and breakers (or fuses) for pv, wire, and maybe something like a midnite e-panel.for a place to neatly mount breakers and bussbars.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    After re-reading my response, I think I need to be more to-the-point:

    The Xantrex / Schneider MPPT60-150 cannot be used with those panels and a 48V battery bank. It simply won't work.  Consider the MidNite Solar 200 or the Magnum PT-100, and connect panels in series to get enough voltage for an MPPT controller to be able to effectively charge a 48V bank.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • mcgivormcgivor Solar Expert Posts: 3,204 ✭✭✭✭✭
    Horsefly said:

    Not sure the Schneider MPPT60-150 is your best choice. I am using it, but in your case it may not be the best. The MPPT60-150 goes into a derated mode at 140V input. Although it isn't harmed by anything until 150V, that makes the upper limit you need to design for at 140V.  At that elevation in Colorado, you will have some very cold temperatures and so you'll need to design allowing for a pretty high Hyper-Voc. I assume those panels are nominal 24V panels (72 cell?), so you will only be able to use two in series for each string. 

    Since your other stuff is Magnum, you should consider the Magnum PT-100. It would tie in nicely to your other Magnum stuff. It can handle input voltage of 200V + the battery voltage, so 248V in your case. That means you can probably go to 3, or maybe even 4 (I'd need to do the math) panels in series. It also can put out 100A, probably making better use of your array. Note that I know nothing about the battery you are planning, so you may have to limit the charge to way under that 100A.

    Steve

    Edit: Holy cow! Those panels are almost 70V Voc! You wouldn't even be able to do two in series with the MPPT60-150. I couldn't find the Voc temp coefficient, but you may be unable to do more than two panels in series even with the PT-100.


    Those panels are 96 cell  hense the 70V voc, 60 cell panels would probably  be more appropriate and less expensive per watt. Don't see 96 cell often, not really a good fit for off grid controllers, unless using the 600V units, from briefly looking around they seem to be primarily used for grid tied systems.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    After reading a bit about these panels, something isn't sitting well. What is "hybrid tunnelling junction technology". Is that different than a regular p-n junction? Sounds to me a bit like vapourware that gets government money to make a cheap panel in a misguided effort to make a panel that competes with chinese panels for long enough for principals to cash out. Man I'm getting cynical!
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mcgivormcgivor Solar Expert Posts: 3,204 ✭✭✭✭✭
    edited June 2017 #8
    Some reading material about tunnel junctions, there are probably others like LG and Panasonic, who use the same technology but don't use the catch phrase so a promotional pitch. Second link has excellent information about panel efficiency.
    http://www.semiconductor-today.com/news_items/2016/feb/ucsb_100216.shtml
    http://news.energysage.com/what-are-the-most-efficient-solar-panels-on-the-market/
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Thanks Guys, sorry for the late reply been hectic the last few days. Pouring foundation, they started drilling the well this afternoon, and I built a solar repeater today to get internet out to the property. Thanks for the replies, I have some questions once I get time tomorrow. 
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Guys thanks for looking into those panels for me, of course, they are the only part of the system I have already bought, I got them for $100 per panel new, So it was a good deal at the time I just did not look into the details at the time. 
    Where the panels will be placed will be a nice clear area within 80' of the house and will be easy to keep an eye on and keep clean. 

    Out of the 2 Charge controllers "Horsefly" recommended what would you guys go with? 

    Thanks for the input so far. 
  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    There's something to be said for staying with one brand for control and monitoring. I don't find it to be much of an issue having a mix though, and the classic200 is less money.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • littleharbor2littleharbor2 Solar Expert Posts: 1,450 ✭✭✭✭
    The Classic 200sl is even less. I see them under $500.00

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    With either the Classic 200 or the Magnum PT-100 you would be fine with one controller and those panels. If you used 6 strings of 2 panels each, you would have a total Vmp to the charge controller of 155V, and total current of 31.9A. You told me in a PM you were hoping to do two arrays of 6, so you'd have half of that current from each, or around 16A. That would be pretty manageable in terms of wire to the charge controller. 

    On the other hand, you could wire three of the panels in series based on the Hyper Voc calculation I did. That would mean two strings of 3 in each of the two arrays. Then you would have a total Vmp to the charge controller of 172V, and Imp total of 10.6A from each of the two arrays. 

    My guess is that the MPPT efficiency for your 48V battery bank might be a little higher with the strings of 2 panels than with the strings of three, but either should work well. The wire losses with the lower current strings of 3 may make the efficiency a wash between the two (6 strings of 2 vs 4 strings of 3). 

    Anyway, since you already have the panels but not the charge controller, keep the panels and go for either of the other two charge controllers.  I personally prefer the idea of going with the Magnum if you are getting the Magnum inverter. That way when something goes wrong you can contact one vendor and they won't be pointing fingers at each other.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Thanks 
    So next question,
    Can you explain to me how I go about combining the strings of panels to go to the charge controller?  
    Do I need a combiner box on each array pole or should I make one that both arrays share? Also is it smart to put a breaker "disconnect switch?"  beyond that at the poles so I can turn off and isolate the panels from the rest of the system?

    What is the best way to combine everything at my panels ( 2x poles with 6 panels on each) before going into the ground and into the system in the house? 

    Also, I have extra panels if you guys think it would be better to have different arrays set-up then described above.

    Then when I get to that point is there a system for calculating what type of wire I will need from the panels to the house? (should be about 80' from panels to house)


  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    The wire you'll need depends on which of the two configurations you choose: 6 strings of 2 panels, or 4 strings of 3 panels. It basically comes down to the current (Imp). You lose power due to the very small resistance in the wire. The more current, the more resistance. The only way to make the resistance lower is to use bigger wire. There are on-line tools for the loss on the wire, but the calculation is really easy using the NEC table. Let me know which of the two configurations you want to use, and I'll tell you what wire you need from each of your two poles.

    As for wiring things together: You'll probably want a combiner box on each pole. It isn't strictly needed if you only have 2 strings of three panels on each pole, but you may want one anyway with breakers to shut off each string separately. That will be useful if you need to troubleshoot the array.  So those combiner boxes will allow you to have one positive and one negative from each pole into the house. You're going to need a breaker panel of some type at the electronics. You would need a breaker on the input to your charge controller, and one on the output. In your case, you can just make it two breakers on the input (one for each pole), and tie them together on the charge controller side.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    So I went ahead and did the calculations. Assuming 80 ft from the poles to the panel in the house, and 3% total loss on the wire into the house:

    If you do 3 strings of 2 panels on each pole, the voltage Vmp will be 115V, and the current Imp will be 15.96A. You can use any wire that has resistance of 1.351 ohms/kft or lower. According to NEC ch 9 table 8, you'll need #10 wire or larger.

    If you do 2 strings of 3 panels on each pole, the voltage Vmp will be 172.5V, and the current Imp will be 10.64A. You can use any wire that has a resistance of 3.04 ohms/kft or lower. From the same table, you would be fine with #12 wire or larger.

    In both cases, the rated ampacity of the wire is more than enough.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Thank you "horsefly" Awesome! 
    If it was you would you do 3 strings of 2 panels or 2 strings of 3 panels?
    What just makes more sense to you for this set-up. 

  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    Well, like I said: 172.5V at max power (and only #12 wire), or 115V at max power (and #10 wire). An MPPT controller can bring either down to the 58V or so you need to charge your 48V battery bank. I would guess that there is some small efficiency difference between bringing 172.5V down to 58V vs bringing 115V down to 58V.  I'm not sure though, so maybe some of the experts here can chime in.

    If you ran 3 strings of 2 panels on each pole, you'd need three breakers in your combiner box, whereas you only need 2 if you do 2 strings of three. Pretty trivial difference.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • littleharbor2littleharbor2 Solar Expert Posts: 1,450 ✭✭✭✭
    edited June 2017 #19
    Technically if only two strings, breakers or fuses aren't needed. I'd still use them for maintenance/troubleshooting.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    Midnite has (had?) some efficiency charts to estimate various combinations on their site.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    Well, I think I found what @Estragon is talking about, and the graphs seem to indicate no change in efficiency, if I am interpreting them correctly.

    So, I'd say go ahead and do strings of 3 panels in series. On each pole, you would have two such strings, which come together at a combiner and go into the electronics on #12 wire or larger.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    The chart I'm thinking of shows a difference of ~750w between a maxed out classic200 at 70v vs 140v. You would need to interpolate the estimated loss on 2 of these panels vs 3. Against that loss is the incrimental local cost of wire over 80' to run lower voltage strings.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • HorseflyHorsefly Registered Users Posts: 368 ✭✭✭✭
    edited June 2017 #23
    I think you are probably right @Estragon, although I couldn't figure out that graph that clearly. Looks like output volts is the amps divided into the watts. Not sure what it tells me.

    I knew I had seen something though, and here's the page I managed to find: https://www.homepower.com/input-voltage-controller-efficiency  It basically says that a 4-to-1 ratio of input voltage to output voltage is 0.5% less efficient than a 3-to-1 ratio. In the OP's case, he's looking at about a 3-to-1 (172.5V to 58V) vs a 2-to-1 (115V to 58V). I'm guessing it is less than 0.5% difference, so I think he is fine either way. Go for the lower cost wire!   :)
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 4 x Vmax XTR12-155 12V, 155AH batteries in a 2x2 24V 310AH bank.
  • EstragonEstragon Registered Users Posts: 4,290 ✭✭✭✭✭
    I agree that either way works. 80' isn't that far, but savings in wire add up.

    One other factor I would consider (though may not be a biggy) is the efficiency loss manifests as more heat in the controller and potentially shorter life.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Horsefly said:
    Well, I think I found what @Estragon is talking about, and the graphs seem to indicate no change in efficiency, if I am interpreting them correctly.

    So, I'd say go ahead and do strings of 3 panels in series. On each pole, you would have two such strings, which come together at a combiner and go into the electronics on #12 wire or larger.
    That sounds like a plan and will work nicely on my panel set up. 

  • PhotowhitPhotowhit Solar Expert Posts: 5,038 ✭✭✭✭
    GB does not size their batteries correctly! They post exaggerated 20 hour rates. I just posted this in another thread so this is copied from that. There are a couple other threads here explaining this...

    I have a 12-85-13 GB battery!

    They do NOT size batteries correctly for a 20 hour rate! Their stated capacity is much higher than the actual capacity.

    This is hard to explain, but perhaps easiest to show you;
     
    If you go and look at your battery spec's at GB it is a 12-125-15, that is a 12 cell battery with 125 amp/hours storage per positive plate (6 hour rate), with 15 plates per cell (7 of which are positive) and they come up with a (7x125=)875 Ah battery at the 6 hour rate. Some how they get 1379 for a 20 hour rate, which is about 1.575 x the 6 hour rate.

    Lets compare Crown's rating, Here is a link to a Crown battery with a similar size at 20 hour rate. It's a 12-100-23 or a 12 cell battery with 100 amps/hours storage per positive plate, and 23 plates per cell, 11 of which are positive, (11x100=)1100 ah battery at the 6 hour rate. Somehow they get 1375 AH at a 20 hour rate, about 1.25x the 6 hour rate.

    I was more than a little upset when I was told this, but it makes sense. BTW-It's rated capacity for the 20 hour rate is also 1.575 x it's 6 hour capacity.

    So realistically the 12-85-13 battery is about 640Ah at a 20 hour rate.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • AndyIvyAndyIvy Registered Users Posts: 12 ✭✭
    Thanks, Photowhit, 
    I did come across that while researching the battery so I was aware they had fudged the numbers a little. 
    Did not know it was quite that low. But felt like it was still a decent choice. 

    Any advice for me charging that battery with my set-up? Any good threads I can read up on for caring for those batteries?

    Thanks 
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