200 watt solar wiring

er78mph
er78mph Registered Users Posts: 3

Hello and thanks all in advance.

 

I will be buying a pair of 100 watt panels and have a ton of questions but I will limit them to maybe ten lol.  I have a 27’ trailer that I like to dry camp with and would like not to depend on a generator.  Our energy use is not that much and would not be able to tell you actual numbers.  I have a pair of 6v batteries wired in series.  My question is how to wire the panels down to the batteries?  I know that there are shunts, fuses, charge controllers, and a battery monitor in my case.  I know fuse sizes depends on wire gauge and other variables but I would love a DIAGRAM to begin. I had a diagram drawn out with the panels, controller down to the battery but I TOTALLY derailed with the battery monitor.  I simple diagram to show me the order from the panels down to the battery would be amazing! I also have a 600 watt in inverter in the mix wired directly to the batteries.   There are a bunch of diagrams but i would like a customized one to get me started. Thank you thank you thank you! And will hopefully hear from you guys at your earliest convenience!!

here is what I am getting for my starter kit from Amazon


bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt by bayite

Renogy 200 Watt 12 Volt Monocrystalline Solar Starter Kit with Wanderer




 

 

Edgar

Comments

  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    The first thing I see on the Amazon page for the meter is some pretty clear diagrams. Sounds like you don't want to do any of the work yourself and need to pay an engineer to draw up some custom drawings then pay someone to do the install.

    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.

  • er78mph
    er78mph Registered Users Posts: 3
    Not necessarily,  I just want clarity and piece of mind.  I've never been accused of being lazy buddy but thanks for your two cents.  If you don't do it everyday, the work might not seem as clear as they do to you.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    It is a bit difficult to give you the "exact" wiring diagram without knowing more about what you want to do.

    However, to get started, it is not really too difficult.

    First, treat the battery bank as the heart of your system. Wire the series/parallel wiring of the battery bank to manage the maximum of amount of Load/Charging current you plan on. If you are paralleling more batteries in the future, read here:

    http://www.smartgauge.co.uk/batt_con.html

    Generally, the negative side of the battery bank is "grounded" to water pipe/ground rod/chassis of vehicle (smaller system may not "earth ground" the battery bank). You put fuses/breakers on the + (positive) leads leaving the battery bank. Breakers are nice (both protect against over current, and provide a handy on/off switch). Each + wire that leaves the battery bus should be fused to the appropriate amount of current. Conservative would be to estimate the maximum current and multiply by 1.25x (i.e. 20 amp max continuous current x1.25 = 25 amp rated branch circuit + fuse/breaker).

    You can use the NEC chart for wire ratings (use the full table in NEC book for full understanding of deratings):

    https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

    You can also use boating ratings for wiring--But these are less conservative (recommend NEC table):

    http://www.boatus.com/boattech/articles/choosing-cables-and-terminals.asp

    Off grid battery charging/solar charging/etc. can have maximum current going to battery bank for multiple hours--Being conservative on wiring keeps the wires from running hot--And gives you lower losses. Also, AC inverters typical surge about 2x rated current for a few seconds to a few minutes (starting well pumps, etc.).

    Also--When wiring up your charging system--I would suggest that you allow for a maximum of 0.05 to 0.10 volts drop (12 volt battery bank) for accurate battery voltage measurements by the charge controller (0.1-0.2 volts for 24 VDC; 0.2-0.4 volts for 48 VDC bank). You can use a simple voltage drop calculator like this (one way wiring run, AWG of cable, and max continuous charging current expected):

    http://www.calculator.net/voltage-drop-calculator.html

    Also, for loads, you want to make sure your DC voltage drop is within reason. A typical maximum recommend drop would be 0.5 volts (12 volts; or 1.0 for 24 VDC; 2.0 for 48 VDC battery bank). This allows for (at 2x rated current for surge) a 1.0 volt (11.5 volt battery operating voltage - 1.0 volt drop = 10.5 volt battery cutoff for AC inverter).

    Note--For high current wiring--Even if you are running negative ground in a vehicle--It is a very good idea to run a full size cable on the negative (return) leg back to the battery. Vehicle grounds between sheet metal and chassis are not of "good quality"--High current can cause pitting/burning at poor connections, and/or intermittent connections (chassis grounds are usually "jumpered" with braided cable--such as HAM radio installations).

    The power meter you have--Generally the shunt is place in the negative lead of the load current to be measured. This is because the two cables that measure the voltage drop across the precision resistor are at "zero volts" and don't need fusing--If the shunt was on the "hot side" of the wiring, a shorted shunt sense lead could cause a fire.

    Note you can have multiple charging source.. The solar charger running directly to the battery +/- bus connections. A second charge controller to the same +/- connections (note, each controller should have its own fuse/breaker in the positive lead). Running controllers in parallel is generally OK. A simple "dumb charger" connected to the AC genset runs a few hours for backup charging. The solar will be your main charging source and 3 or 4 stage charging.

    You can also get an inverter-charger--These can be very nice because the inverter-chargers are generally "better" and more configurable charge controllers vs the "dumb" chargers.

    Anyway--That is a start.

    My general recommendation is to design your battery bank to support your loads (xyz Watt*Hours per day; 2 days of no-sun; 50% maximum discharge). And the solar system to recharge your battery bank at both 5% to 13% (typical) rate of charge (i.e., 100 AH battery bank, 5-13 amps rate of charge). 10% or higher rate of solar charge if full time off grid. 5% is OK for a weekend/summer cabin usage.

    And, a second design check is that your solar array supplies enough Watt* Hours per day to recharge the battery every day (say for 9 months of the year--During winter, many folks need backup genset during dark weather).

    You really want your system to keep the battery bank "happy". Under charging/deficit charging/running battery bank dead/not keeping electrolyte above plates with distilled water--Are typical ways of killing the battery bank before its time.

    I will stop here... Your questions?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited January 2017 #5
    Very nice @BB. Wish I had asked a question and got an answer like that before starting out.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Unfortunately--The details matter in solar design and engineering.

    We can design to your loads (and location)--Or we can design to another "major" component. Let us say you have 2x 6 volt @ 200 AH batteries for a 12 volt @ 200 AH battery bank.

    Nominally, for a full time off grid system, I would suggest that you design for 2 days of "no sun", and 50% discharge on the battery bank--Or your battery bank is ~4x your daily load.

    However, for RV's, typically weight and space are limitations... And you could justify 1 day of storage and 50% discharge--Assuming you are (mostly) summer (non-winter) weekend/2 week camping. Plan on using a backup genset or simply not using power during bad weather.

    So--Which would you like to plan for--1 day or 2 day of storage? And where (roughly) will you be camping (i.e, sunny southwest in the summer, or Canadian wilderness in dead of winter). Obviously, but stated anyway--Solar panels only work with the sun. Shading/winter fart north, etc.--You do not get much energy from solar panels.

    Generally, load conservation can be a big help... I.e., a typical RV heater has forced air heating with a fan that draws ~8 amps @ 12 volts (96 Watts) when running--And perhaps a 25-50% duty cycle in very cold weather. Switch to a catalytic/non-forced air heating system can reduce loads.

    Using a small laptop or tablet+cell phone for Internet access vs a full size desktop computer can save lots of power too 10-30 watts vs 100-300 Watts for a full size desktop). LED TV (or laptop computer+digital receiver) vs an older TV can save power. And LED lighting vs filament lamps, etc. all help a lot.

    Just to give you an idea... 500 Watt*Hours per day for an off grid small cabin (lights, small radio/tv/tablet) is not bad. And a 1,000 WH per day system will give you enough power for a laptop+lights+RV pump+cell charge pretty nicely.
    • 500 WH per day / 12 volts = ~42 Amp*Hours per day @ 12 volts
    • 1,000 WH per day / 12 volts = ~83 Amp*Hours per day @ 12 volts
    Now, a 12 volt @ 200 AH battery bank:
    • 12 volts * 200 AH * 1/2 days storage * 0.50 maximum discharge * 0.85 efficient AC inverter (for 120 VAC loads) = 510 WH per day
    • 12 volts * 200 AH * 1/1 days storage * 0.50 maximum discharge * 0.85 efficient AC inverter (for 120 VAC loads) = 1,020 WH per day
    Say you camp in the Southwest US mostly in the summer, and you mount panels flat to roof (you can play with numbers/locations/tilt for more information)... Using a solar handbook for Yuma Az:
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Yuma
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a horizontal surface:
    Jan Feb Mar Apr May Jun
    3.19
     
    4.06
     
    5.29
     
    6.30
     
    7.41
     
    7.69
     
    Jul Aug Sep Oct Nov Dec
    7.00
     
    6.15
     
    5.25
     
    4.38
     
    3.45
     
    2.94
     
    Toss the bottom three months (winter), your "break even month" would be February at 4.06 "average" hours of sun per day. Say you want 1,020 WH per day of 120 VAC power:
    • 1,020 WH per day * 1/0.52 average off grid system eff * 1/4.06 hours of sun (Feb) = 483 Watts of Solar array (Feb break even month)
    Next, what can 12 volt @ 200 AH flooded cell battery bank power? Nominally, some of the numbers would look like (using rules of thumbs):
    • 12 volts * 200 AH * 0.85 AC inverter eff * 1/20 hour discharge rate = 102 Watts of AC power average (10 hours total, 50% discharge)
    • 12 volts * 200 AH * 0.85 AC inverter eff * 1/8 hour discharge rate = 255 Watts AC max continuous discharge (less than ~4 hours to 50% discharge)
    • 12 volts * 200 AH * 0.85 AC inverter eff * 1/5 hour discharge rate = 408 Watts AC max short term (minutes to an hour)
    • 12 volts * 200 AH * 0.85 AC inverter eff * 1/2.5 hour discharge rate = 816 Watt AC max surge (seconds to minutes)
    So--Before we have picked any hardware, we have a paper design of what such a system is capable of.

    Once you have a system penciled out--Then there is picking the hardware (specific solar panels, PWM or MPPT charge controller, AC inverter, backup battery charge, etc.).

    Does this help?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • er78mph
    er78mph Registered Users Posts: 3
    Bill, I greatly appreciate the time and effort put forth on your post.  I will take your information and resources to continue my journey of solar technology.   I will take time to draw out a diagram and continue to educate myself and implement what you shared.  Thank you, and YES your information is priceless.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    2manytoys has posted his ongoing/mostly DIY solar project on his website (about 1/2 way down):

    http://www.2manytoyz.com/

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Nvreloader
    Nvreloader Solar Expert Posts: 71 ✭✭
    Bill
    Thank you for this info, was a big help.


    Tia,
    Don
  • Rayson
    Rayson Registered Users Posts: 21 ✭✭
    BB. said:

    Quote: We can design to your loads (and location)--Or we can design to another "major" component. Let us say you have 2x 6 volt @ 200 AH batteries for a 12 volt @ 200 AH battery bank.

    Nominally, for a full time off grid system, I would suggest that you design for 2 days of "no sun", and 50% discharge on the battery bank--Or your battery bank is ~4x your daily load.

    However, for RV's, typically weight and space are limitations... And you could justify 1 day of storage and 50% discharge--Assuming you are (mostly) summer (non-winter) weekend/2 week camping. Plan on using a backup genset or simply not using power during bad weather.


    Quote: Say you camp in the Southwest US mostly in the summer, and you mount panels flat to roof (you can play with numbers/locations/tilt for more information)... Using a solar handbook for Yuma Az:
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Yuma
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a horizontal surface:
    Jan Feb Mar Apr May Jun
    3.19
     
    4.06
     
    5.29
     
    6.30
     
    7.41
     
    7.69
     
    Jul Aug Sep Oct Nov Dec
    7.00
     
    6.15
     
    5.25
     
    4.38
     
    3.45
     
    2.94
     
    Toss the bottom three months (winter), your "break even month" would be February at 4.06 "average" hours of sun per day. Say you want 1,020 WH per day of 120 VAC power:
    • 1,020 WH per day * 1/0.52 average off grid system eff * 1/4.06 hours of sun (Feb) = 483 Watts of Solar array (Feb break even month)
    -Bill

    Hi Bill,
    How did I go applying the information here: http://forum.solar-electric.com/discussion/comment/366157/#Comment_366157
    Thank you.
    Ray

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Ray, I have made a post on your thread...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset