Wiring solar panels

Yerf
Yerf Registered Users Posts: 65 ✭✭
edited October 2017 in PV Installers Forum - NEC, Wiring, Installation #1
Hello

I have 15 Trina Solar panels TSM-255
PC05A/
05A.08

How can I wire these with a victron 150/70 mppt charger?

Lowest ambient temperature - 1 c highest 45 c
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    You would want to give the specs for the solar panels VOC VMP as well as your system voltage (battery bank voltage).
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #3
    What is your battery bank voltage? Generally, the Vmp-array voltage for a 150 Volt max MPPT controller, the Vmp-array voltage should be around 1.3x Vbatt-charging to Vmp-array=~100 VDC standard.

    The typical "optimum" (for MPPT controller) would be to have Vmp-array~2x Vbatt-charging (i.e. 15 volt charging Vmp-array~30 volts).

    -Bill


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #4
    Trina Solar panels

    Peak Power Watts-PMAX (Wp) 255
    Power Output Tolerance-PMAX (%) 0/+3
    Maximum Power Voltage-VMP (V) 30.9
    Maximum Power Current-IMPP (A) 8.26
    Open Circuit Voltage-VoC (V) 38
    Short Circuit Current-ISC (A) 8.95
    Module Efficiency ηm (%) 15.6
    open Circuit Voltage (V) 34.9
    Maximum Power Current (A) 6.68
    Short Circuit Current (A) 7.24

    Victron charger
    150 volts max 50 A max
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #5
    What voltage battery bank?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #6
    51.2 V nominal
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #7
    5 strings of 3 panels in series for Voc of 38x3=114v.
    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
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #8
    Will the charger be enough in a 48v system?

    255x15= 3825 / 48 =79. 68

    So I am 9.68 amps over. The question is will the panels ever produce 79.68 amps?
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  • Horsefly
    Horsefly Registered Users Posts: 476 ✭✭✭✭
    edited October 2017 #9
    First off, for a 48V battery bank you will actually be charging at closer to 59V. So 3825 / 59 is closer to 65A.

    Second, you'll never in real life achieve the full nameplate power from the panels.

    Finally, the charge controller will only take the power it needs / can handle.  You should be able to set the limit on current from the CC to the batteries.

    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #10
    > @Horsefly said:
    > First off, for a 48V battery bank you will actually be charging at closer to 59V. So 3825 / 59 is closer to 65A.
    >
    > Second, you'll never in real life achieve the full nameplate power from the panels.
    >
    > Finally, the charge controller will only take the power it needs / can handle.  You should be able to set the limit on current from the CC to the batteries.

    I will be using victron lifepo4 batteries which have a maximum charge voltage of 56.8

    So ı should be fine also.

    How about fusing. I should fuse every string with 15A 48v fuse? And the whole panels with 75 A 48v fuse?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #11
    I mostly agree with Horsefly, but just to pick a couple of nits:

    Unlikely in OPs climate, but in a cold high altitude location, getting somthing close to STC rated output may be possible.

    Also, the bank may absorb around 59v, but will bulk (at full current) at lower voltages. At a low SOC, that could < the 51.2v nominal. In real life, this isn't normally an issue, as the weaker morning sun means a lot of bulk is often done with less current. I have some morning shade issues though, so between that and a few clouds, it sometimes works out that bulk starts with a pretty strong sun.

    As Horsefly said though, you can normally limit charging current in the controlller anyway, and the panels won't produce more than the load. Best to set the limit, and have some extra panel for getting some charge on lightly overcast days.
    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
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #12
    @Yerf
    The charge controller will not produce any power above it's rating, so it's ok to be slightly over paneled.
    Looks like absorb setting is 56.8, what is the float setting? How many amp hours is the battery bank? Just curious because I have a 195AH LiFePO4 battery bank myself.

    I would try to use a combiner box with 15 amp 150 volt DC breakers, one for each string. It makes it much easier to test and troubleshoot array problems. Here's a link to a combiner box and breakers:
    https://www.solar-electric.com/mnpv6.html
    https://www.solar-electric.com/mnepv.html

    The breaker size for PV wire in to the CC depends on the size of the wiring, However I would use  #4 AWG or metric equivalent and an 80 amp 150 volt DC breaker. Makes for a convenient switch also. Here's the link:
    https://www.solar-electric.com/pamodccibr.html

    Rick
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #13
    @Raj174 thank you for your reply

    The float voltage is 13.5 V for each battery so 54 V for the bank. The batteries are 12.8 V each rated 100 Ah. They will be connected with a victron BMS which handles overcharging and discharge cut off.

    https://www.victronenergy.com/batteries/lithium-battery-12-8v

    Is it healthy to trickle charge these batteries on float?

    Also manufacturer recommended to charge each battery separately before connecting in series with a plug in charger at 100ah/20 to fully charge and balance cells. Is this something you did. I'm a bit worried about these lifepo4 cells as they seem a little less stupid proof than lead acid.

    DO I have to use 150vdc breakers? What if they were a higher or lower voltage? As it may be hard getting my hands on those?
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #14
    Look for Midnite Solar DC breakers. The forum's host, NAWS has them.  Amazon and eBay carry them.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #15
    Yerf said:
    DO I have to use 150vdc breakers? What if they were a higher or lower voltage? As it may be hard getting my hands on those?
    I is important to use DC rated breakers with a voltage rating above the voltage that they will see. DC breakers are designed differently than AC breakers.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    edited October 2017 #16
    @Yerf
    Thank you for the information. This is the first time I have heard of 12 volt battery packs that the manufacturer allows series connection. All others are parallel only as far as I know.
    If you mean, reaching and maintaining float during everyday cycling, then I don't see a problem with that.  

    I agree, charge each pack individually to 100% then connect in series, that way all the packs should stay fairly close to the same voltage.

    I wouldn't be worried about the cells, each one has a BMS that will monitor and protect the cells. Also, if you follow Victron's configuration and charging recommendations then they should be covered by the warranty.
    My bank is composed of 16 195AH 3.2 volt prismatic cells, so very different than yours. Charging voltage is a good bit lower than yours at 54.8V because I don't use a BMS.

    As to the breakers, they have to be DC rated breakers, and I only know of 150V and 300V sizes. If breakers are a problem then fuses will do, just not as convenient and are probably cheaper. Combiner boxes that use fuses are available, you might google that if you're interested.
    Just be sure not to remove a fuse while DC current is flowing through the circuit, bad things can happen.

    Rick 
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #17
    Square D QOU breakers are DC rated for up to 48 volt systems. The data sheet shows them rated for 48 and 60 volts DC.

    Page 7 points this out. http://download.schneider-electric.com/files?p_Reference=0720CT9401&p_EnDocType=Catalog&p_File_Id=7442938932&p_File_Name=0720CT9401R105.pdf

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #18
    @Raj174 yeah I like that they are 12v much more useful to me that way.

    DO you think I could charge them in parallel on their first charge?
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #19
    @Photowhit higher voltage than they will see? For example the inverter could have a 60vdc 200 amp breaker since my battery bank is 48v, am I right?

    The solar panels will be max 150 V so they could have 200 Vdc breakers right?
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    edited October 2017 #20
    Yerf said:
    @Raj174 yeah I like that they are 12v much more useful to me that way.

    DO you think I could charge them in parallel on their first charge?
    You can, but be sure to watch the pack with the highest voltage and stop charging before it reaches 14.2 volts. Then disassemble and charge individual packs to 100%.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #21
    @Raj174 sounds good to me
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #22
    Could I use these LANGIR 16A 250V DC Single Pole DC Circuit Breaker Switch C Curve With TUV Certificates https://www.amazon.co.uk/dp/B06VV7SRBM/ref=cm_sw_r_cp_apa_-fM6zbBXP8Z8R
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #23
    Yerf said:
    Could I use these LANGIR 16A 250V DC Single Pole DC Circuit Breaker Switch C Curve With TUV Certificates https://www.amazon.co.uk/dp/B06VV7SRBM/ref=cm_sw_r_cp_apa_-fM6zbBXP8Z8R
    Yes, that looks like it will work fine.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #24
    Yerf said:
    Could I use these LANGIR 16A 250V DC Single Pole DC Circuit Breaker Switch C Curve With TUV Certificates https://www.amazon.co.uk/dp/B06VV7SRBM/ref=cm_sw_r_cp_apa_-fM6zbBXP8Z8R
    Yes, that looks like it will work fine.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #25
    @Yerf
    This breaker has a din rail mount, so the combiner should have a din rail for mounting the breakers.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #26
    In the manual for the batteries it says

    "Do not interconnect the intermediate battery to battery connections of
    two or more parallel strings of batteries."

    What does it mean?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #27
    Just guessing, but maybe they're trying to say you need to protect a bank with more than two parallel connection with a fuse or breaker for each parallel connection.

    The issue being that in the event of a short fault occuring in a parallel bank of three or more such connections can put the current of the remaining batteries or series strings through the shorted one.
    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
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #28
    What do you guys think of this guys method of cell balancing? https://youtu.be/7QRpz6u86_8

    Because I will have 24 PCs of 12.8 V lifepo4 batteries to balance when I get them. And I really don't want to do them one by one.

    Also how often do you have to balance cells in lifepo4 batteries? Is it just once when you get them or is it like once every few months?
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    edited October 2017 #29
    @Yerf
    I wouldn't do it that way. I would use that method to bring them close to full and then finish the charging individually following Victron's recommendation. I believe that the time it takes to to it properly will pay off.

    Rick
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #30
    How about cable size from the panels to the charger? It's about 35 m distance.
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    edited October 2017 #31
    @Yerf
    If you're using a combiner box at the array, then a #4 AWG cable will work with a 2% voltage drop. Metric equivalent is 5.189 mm or 21.2 mm squared.
    http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.8152&voltage=114&phase=dc&noofconductor=1&distance=35&distanceunit=meters&amperes=41&x=60&y=14

    Rick  
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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