Advice on this system and can an MC4 connector connect directly to a circuit breaker?

Hello everyone!

I'm a newcomer to the forum and solar power in general and so far this forum has been a treasure chest of information for me, which i highly appreciate. However, I would like to know if an MC4 connector, male or female, can connect directly to a DC circuit breaker?

I'm planning to construct a system with 8 100W panels connected in parallel running to an Outback Flexmax 80 FM80 MPPT 80 AMP Solar Charge Controller, which feeds a
Power Bright PW6000-12 6000 Watt Power Inverter...i've found an article showing how to construct your own solar combiner box, what amperage should the circuit breakers be and any thoughts and advice on that system? I'll upload drawn schematics to the thread shortly
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Comments

  • solar_davesolar_dave Solar Expert Posts: 2,343 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Do you have any idea how big a wire you will need to get 6000 watts @ 12 volts, that is 500 amps without any surge figured in. WOW!
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    This should give you an ideal of the mc-4 connecting. I don't remember for sure so wait for some one else to answer but I believe you times your amps by 1.56 and that is the size breaker you use. The back of the panel should tell you the max breaker you can use if you put the panels in series.

    Here is the link for ideals.

    http://www.solar-electric.com/installation-parts-and-equipment/midnite/pvarco/prpvcobo/misomnsoarco5.html

    Good luck
    gww
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    Hello everyone!

    I'm a newcomer to the forum and solar power in general and so far this forum has been a treasure chest of information for me, which i highly appreciate. However, I would like to know if an MC4 connector, male or female, can connect directly to a DC circuit breaker?

    I'm planning to construct a system with 8 100W panels connected in parallel running to an Outback Flexmax 80 FM80 MPPT 80 AMP Solar Charge Controller, which feeds a
    Power Bright PW6000-12 6000 Watt Power Inverter...i've found an article showing how to construct your own solar combiner box, what amperage should the circuit breakers be and any thoughts and advice on that system? I'll upload drawn schematics to the thread shortly

    Welcome to the forum.

    We need to do some clarification here.

    First, as solar_dave said a 6kW 12 Volt inverter will draw an enormous amount of current. In short form, it's a piece of junk. Get rid of it if you seriously need that kind of power. You should have a 48 Volt system if you need that level of output.

    Second, a charge controller does not feed an inverter. Off-grid inverters run from batteries. Charge controllers recharge the batteries. It is important to keep the ideas separate.

    Third, an MC4 connector is designed to go between another MC4 connector and a piece of wire. There is no way the wire end will attach directly to a circuit breaker. Or perhaps I should say "no safe way" as so many people are intent on doing things wrong. Often because they saw some idiot put up a Youtube video about it.

    Fourth, 800 Watts of PV as four 100 Watt panels on an MPPT controller: unless you already have the panels there are cheaper options to get that much power from an array with fewer panels. As it is you could put the panels in strings of two each and have four strings. Most sensible way to combine the four strings is wit a MidNite combiner box. It may not cost less than your DIY box, but it's guaranteed to be built right. At least take a look at their design; the MC4 connectors are built-in to the box.

    Fifth, the panels will have a maximum series fuse rating on them. This is the most current they can handle as a conductor if something goes wrong. It is usually, but not always, 15 Amps. That is the size of individual string breakers you would use.

    Finally, remember you will also need fuse/breaker on the output of the charge controller to the batteries and another on the wire from the batteries to the inverter.
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    Welcome to the forum.

    We need to do some clarification here.

    First, as solar_dave said a 6kW 12 Volt inverter will draw an enormous amount of current. In short form, it's a piece of junk. Get rid of it if you seriously need that kind of power. You should have a 48 Volt system if you need that level of output.

    Second, a charge controller does not feed an inverter. Off-grid inverters run from batteries. Charge controllers recharge the batteries. It is important to keep the ideas separate.

    Third, an MC4 connector is designed to go between another MC4 connector and a piece of wire. There is no way the wire end will attach directly to a circuit breaker. Or perhaps I should say "no safe way" as so many people are intent on doing things wrong. Often because they saw some idiot put up a Youtube video about it.

    Fourth, 800 Watts of PV as four 100 Watt panels on an MPPT controller: unless you already have the panels there are cheaper options to get that much power from an array with fewer panels. As it is you could put the panels in strings of two each and have four strings. Most sensible way to combine the four strings is wit a MidNite combiner box. It may not cost less than your DIY box, but it's guaranteed to be built right. At least take a look at their design; the MC4 connectors are built-in to the box.

    Fifth, the panels will have a maximum series fuse rating on them. This is the most current they can handle as a conductor if something goes wrong. It is usually, but not always, 15 Amps. That is the size of individual string breakers you would use.

    Finally, remember you will also need fuse/breaker on the output of the charge controller to the batteries and another on the wire from the batteries to the inverter.


    Thanks everyone so far for your invaluable input

    And in reply to Mr. Cariboocoot's input, instead of using a single 6kW inverter, I was thinking of connecting 2 3kW inverters using a 48V DC input to the battery bank, i was hoping to assemble a 1500Ah battery bank. Your second and third points have been duly noted. With respect to the panels i was doing my scouting on amazon, didn't know there was a store here as well

    any thoughts on using 4 of these, anyone? http://www.solar-electric.com/solar-panels-mounts-kits-accessories/solarpanels/kyocera-solar-panels/kyocera-kd255gx-lfb-255-watt-polycrystalline-solar-panel.html I'm assuming they're 12V panels so i can connect them in series to produce a 48V array, correct? I'm all the way from the Caribbean and relatively new to in depth system solar power system designs, so I'm making sure i have everything understood before I make make the orders, any help and advice would be much, much appreciated
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    any thoughts on using 4 of these, anyone? http://www.solar-electric.com/solar-panels-mounts-kits-accessories/solarpanels/kyocera-solar-panels/kyocera-kd255gx-lfb-255-watt-polycrystalline-solar-panel.html I'm assuming they're 12V panels so i can connect them in series to produce a 48V array, correct? I'm all the way from the Caribbean and relatively new to in depth system solar power system designs, so I'm making sure i have everything understood before I make make the orders, any help and advice would be much, much appreciated

    The are not "12 volt" Panels (Vmp in the range of 17.5 to 19 volts or so):

    • Number of Cells: 60
    • Tolerance: +5%/-0%
    • Vmp: 30.4 volts
    • Imp: 8.39 amps
    • Voc: 37.6 volts
    • Isc: 9.09 amps
    • 65.43" x 38.98" x 1.8"
    • 44.1 lbs.
    • MC4 locking connectors

    Vmp~30 volts is a very standard panel voltage for Grid Tied and MPPT based charge controller systems. They will not work for a PWM (less expensive) type solar charge controller. And Kyocera panels are very good too.

    30 volts is too low of voltage to charge a 24 volt battery bank (need Vmp-array minimum of ~35 volts). As the panels get hot, the Vmp-panel will fall down towards ~24 volts. You need ~28-30+ volts to charge a 24 volt flooded cell battery bank. Two panels in series (Vmp-array~60 volts) will cost you about 40% (60% panel efficiency) of your array's output wattage into a 24 volt battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    BB. wrote: »
    The are not "12 volt" Panels (Vmp in the range of 17.5 to 19 volts or so):


    30 volts is too low of voltage to charge a 24 volt battery bank (need Vmp-array minimum of ~35 volts). As the panels get hot, the Vmp-panel will fall down towards ~24 volts. You need ~28-30+ volts to charge a 24 volt flooded cell battery bank. Two panels in series (Vmp-array~60 volts) will cost you about 40% (60% panel efficiency) of your array's output wattage into a 24 volt battery bank.

    -Bill


    Thank you very much BB. I am indeed planning to install an MPPT based charge controller, currently scouting some Midnite Classics. You said "30 volts is too low of voltage to charge a 24 volt battery bank (need Vmp-array minimum of ~35 volts)" Is there a formula/theory behind it? And if 2 panels in series would cost me about 40% of my array's output wattage into a 24V bank (i assume this loss would increase for a 48V bank), how can i reduce these losses?
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    When you use an MPPT charge controller you do not 'lose' any power, the mppt CC does some conversion so that 100 Watts in,( less some power to run the MPPT and line loss etc still) equals 100W out. Not so with PWM , if that is what you use you will lose everything above the nominal battery voltage (roughly)
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    thank you westbranch, by the way, can you connect 2 or more inverters to the same battery bank? If so, how can that be done and what are the possible consequences
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    short answer, yes, but what are you attempting to achieve? there are issues to be taken care of if you want 2 inverters. Are you after 240V..?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    My main aim is to power as much of my household as possible and by chances what are the issues needed to be taken care of? Im struggling to find sizeable inverters (3kW and up) running on 24V DC input, so i was wondering if i can hook up 2, maybe 3, inverters to the battery bank to achieve the desired power
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Are you wanting 240V?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Sure, that would be welcome
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    here are some choices
    you would need 2 of these at 24V:

    http://www.solar-electric.com/inverters-controllers-accessories/inverters/ouin/oupooffgrand/outback-power-pure-sinewave-inverter-vfx3524.htmll 120V but stackable You can also use an Xformer for 240V
    http://www.solar-electric.com/psx-240.html

    or one of these at 48V:

    http://www.solar-electric.com/inverters-controllers-accessories/inverters/ouin/rasein/outback-power-radian-series-inverter-gs8048.html 120/240

    Just examples
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • mike95490mike95490 Solar Expert Posts: 8,377 ✭✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    My main aim is to power as much of my household as possible and by chances what are the issues needed to be taken care of? Im struggling to find sizeable inverters (3kW and up) running on 24V DC input, so i was wondering if i can hook up 2, maybe 3, inverters to the battery bank to achieve the desired power

    You can, for about 2 minutes :) Then the batteries go flat. If you are wanting 3Kw of power, you need to look to a 48V system, same watt hours, but less loss in system resistances and Peukert losses.

    Outback & Schneider/Xantrex make stackable or native 240V capable inverters. I have XW-6048 and it barely grunts when huge loads (3hp floor sander) are thrown at it.
    Powerfab top of pole PV mount | 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 ,

  • Ethan BrushEthan Brush Solar Expert Posts: 231 ✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Greengen,

    OF course I know very little about what you are trying to accomplish, but it seems like you will need a much bigger array. Hearing 6KW inverters and 800 watts of PV in the same sentence is sort of like hearing "fuel efficient" and "1996 F350 with dump body and 460 gas engine" in the same sentence (I have one its a atrocious!). Also You generally want to connect as many modules in series as you can - check out Midnite's string size calculator. You probably wont need series fuses if you have 2 strings. If you have a MPPT CC there is no reason to worry about what the module voltage is.
    Best
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    Greengen,

    OF course I know very little about what you are trying to accomplish, but it seems like you will need a much bigger array.

    I've done some more extensive research and i've opted to use Kyocera KD325GX-LFB 325 Watt Multicrystalline Solar Modules, so far i've earmarked 3 to import, i use to measure my household's energy consumption, but for the while i plan on sticking with the 6kW inverter, any suggestions on the amount of panels i should include in my PV array?
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Lets backup a moment here.... Your loads drive the battery bank. And the battery bank+loads drives the solar array. Lastly, the peak loads drive the size of the battery bank and the AC inverter.

    To be really helpful, we need to know how much power you plan on using per day. Here is an example of sizing loads for an off grid system. All the below assume that you are conservation minded. Even an efficient set of appliances and loads can be much heavier with teenagers who don't turn things off... Off grid solar system can generate a lot more power during sunny/summer weather--Much less during winter/poor weather. You either have to adjust your power usage, or use a backup genset/over size the system (both are expensive options).
    • 1 kWH per day (1,000 WH per day)--Smallish system. lights, radio, laptop computer, small water pump
    • 3.3 kWH per day--Add a full size refrigertor, well pump, clothes washing machine--About the practical limit for most off grid homes
    • 10 kWH per day--Add electric cooking, fans, irrigation, some small amount of A/C--Lots of money for such a system
    • 33 kWH per day--full A/C in hot climates, electric hot water, electric cooking--Suit cases full of money to build and maintain such a system
    Just to give you an idea of what a 3.3 kWH (3,300 WH) per day system looks like. First how much AC power is that. Assuming 5 hours per night of power:
    • 3.3 kWH / 5 hours = 0.825 kWH = 825 Watt average load per evening (not even close to a 6 kWatt AC inverter needed--perhaps 1.5-2 kWatt inverter max)
    Then the battery bank. Assuming 2 days of storage and 50% maximum discharge (for longer battery life):
    • 3,300 WH * 1/0.85 inverter eff * 1/24 volt battery bank * 2 days storage * 1/0.50 max discharge = 647 AH @ 24 volt battery bank
    To charge this bank, two calculations. First based on size of battery bank (5-13% rate of charge). Second based on loads and amount of sun.

    Based on rate of charge:
    • 647 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 1,218 Watt array minimum
    • 647 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 2,437 Watt array nominal
    • 647 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 3,168 Watt array "cost effective" maximum
    And based on the amount of sun where you live... using Solarelectrichandbook for Princes Town, Trinidad and Tobago (guessing your approximate location), fixed array:

    Princes Town
    Average Solar Insolation figures


    Measured in kWh/m2/day onto a solar panel set at a 80° angle from vertical:
    (For best year-round performance)

    Jan
    Feb
    Mar
    Apr
    May
    Jun


    6.29
    6.37
    6.27
    5.88
    5.89
    5.52


    Jul
    Aug
    Sep
    Oct
    Nov
    Dec


    5.74
    5.73
    5.68
    5.72
    5.49
    5.89


    Near equator, June sun minimum average:
    • 3,300 WH per day * 1/0.52 system efficiency * 1/5.52 hours of sun in June = 1,452 Watt array minimum (based on hours of sun/loads)
    And practially speaking... A 647 AH @ 24 volt battery bank can support about a maximum of 3.25 kWatt inverter. Any larger will simply collapse a flooded cell lead acid battery bank when operated at "full load/maximum surge load". (based on ~0.5 kWatt of AC inverter rating per 100 AH @ 24 volt battery bank minimum)

    For a 12 volt battery bank--You should not plan on pulling more than ~1.5 to 2 kWatts maximum. For a 24 volt battery bank, around 3 to 4 kWatt maximum. If you try to pull more current through the DC wiring--The size/cost of the copper cables makes it difficult to wire and expensive for the copper.

    Nothing written in stone--Just some basic guesswork.

    Your thoughts?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Bill, wow, absolutely wow, I'd love to acquire such knowledge in solar power, I'm a fan of renewable energy based power generation and it'll be an honour to gain such knowledge.
    I plan on obtaining a Kill-a-watt soon to measure the energy consumption of various articles in my home. But a couple of 0.75kW pumps, a laptop that's on 24/7, a fan, a small speaker system, a wireless modem and a couple of smartphones <- that's what I'm aiming to power for the while. I'm planning to have 3 325W solar panels in parallel and a 24V battery bank.
    I redid your calculations and found i need a 1300W array minimum. I'm currently drawing up a "schematic" for my solar power system. I'd like to upload it and have your criticique on it.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    GG, you are very welcome.

    Going back to loads... Pumps, refrigerators, and even fans can all take a relatively large amount of power. Working to minimize those power needs is usually the first step to solar power.

    For water pumps, there are systems that you can allow you to directly connect a smallish solar array directly to your pump/pump electronics. If you need to irrigate and/or pump larger amounts of water to a cistern/holding pond, these type of systems can be very nice.

    And, there are folks that have done several kWatt size three phase pumping systems this way with solar--Very cool (but also pretty cutting edge--local companies may not have much experience):
    BB. wrote: »
    Some discussions about VFD (Variable Frequency Drives)... Basically a variable frequency inverter with (typically) three phase output. Used to soft start motors (handy for 3 phase well pumps, or pumps with well head starting capacitor) and can also turn an AC motor into a variable speed motor (very handy for pumping applications).

    WELL PUMP and Inverter QUESTION

    Wind/solar for large scale pumping etc (out of my depth!)
    could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC (new link/thread 10/27/2012)
    Help required to design off grid system (information on possibilities to connect "standard VFDs direct to solar panels) (new link 1/13/2013)

    For fans--Looking for the most efficient can help too. A standard AC fan may take several hundred watts. A DC fan may take a 1/4 of that (although, generally with a bit less air flow too).

    Anyway... That is how I would start.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    So how would one minimise those power needs? reduced usage?
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    It turns out that older electrical devices usually were not designed to be energy efficient--But just cheap to build.

    For example, many well pumps in the US are 1-2 HP range, when a 1/2 HP would work just about as well. And there is the whole idea of "slow pumping"---Basically let the sun pump for 6 hours per day at relatively low rates and fill a cistern/large pressure tank for momentary home needs (or use a second small ~100 Watt pump to pressurize for kitchen sink/shower/etc.).

    Pretty difficult to make general suggestions (very broad subject--energy conservation). Instead, look at your loads and decide which one (or several) to attack first.

    If you already have a laptop that uses 0.3 kWH per day and a 5 watt cell phone charger--And a pair of 3/4 HP pumps--Look at the pumps first.

    Also peak current and total WH (or kWH per day) are sort of two different problems.

    For example, a microwave uses 1,500 Watts peak, but only 20 minutes per day:

    1,500 Watts * 1/3rd hour per day = 500 WH per day
    30 watt laptop * 8 hours per day = 240 WH per day
    5 watt USB Charger * 4 hours = 20 WH per day
    22 watts of LED lighting * 4 hours = 88 WH per day
    750 Watt pump * 6 hours per day = 4,500 WH per day

    750 Watt pump may take 2-3 kWatts starting surge...

    So--Figure out your present power needs--Cost of larger Off Grid power system vs cost of "new energy conservation appliances/pumps" and see what works out for you. In general, the costs of reduce power needs can be much less than the costs to increase the size/long term maintenance of your off grid power system.

    There are many people here that can help you with conservation... I suggest picking a piece at time. Trying to discuss 5 different "things" gets a bit confusing/frustrating to follow.

    And if you are already running an off grid power system--Telling us a bit about it and how well it works for you (and roughly where it is located) can be helpful too. Adding a signature to your profile (and going to Advanced editing on your post to turn on signatures) will help keep us from asking the same questions of you.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    We do have an older model refrigerator (10 years old) and I'm yet to install an off grid power system, I'm fine tuning my designs then I'll starting importing the components. I have attached some images of my desired system and its battery bank. Any critique, corrections and/or advice would be most welcome. Correction: i've opted to replace the 4000W inverter in the diagram with a 3000W continuous 6000W peak pure sine wave inverter manufactured by Nimble

    Attachment not found.Attachment not found.Attachment not found.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    those Nimble models are not made for being hardwired into house wiring , they have extension cord plugins...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    I personally do not like large numbers of paralleled battery strings. In my humble opinion, 1 string is ideal, many folks like 2 strings (if one string fails, the second can run as as backup until the first is repaired), and 3 parallel strings is about the maximum I would suggest--Unless you have no other choices.

    Before you start drawing everything out--Tells us what you are trying to do. AH/Voltage rating of battery bank, how many Watts of solar panel, and you are looking 3 kWatt of 24 volt AC inverter (?).

    I am a big believer in "balanced" system design. And to do this, you really need to look at the whole system in total. Once you have done the paper parts list (battery bank size, etc.) and are happy with the theoretical results, you can start researching hardware choices that will support your needs.

    There will be lots of trade offs to be made here. If you live somewhere that does not have a wide selection of batteries (voltage, AH, etc.)--You are sort of hosed and force to alter your deign to use what is local (buying batteries from elsewhere can be a pain).

    So:

    1) know your loads
    2) conservation choices (new hardware, reduction of expectations, etc.)
    3) repeat #2
    4) do the 50,000 foot design (just numbers for battery bank, array, etc.)
    4.5) What if/backup design--genset+AC charger specs, spares, etc.
    5) start to "push down" to each sub-section (batteries design first--I would suggest)
    6) order electronics, wiring, racking, etc.
    7) order batteries last (flooded cell batteries will start to "die" if left uncharged for ~1 month or more without charging)

    Do not make any orders until you have a plan that works. Buying pieces without a plan will generally not give you good results.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Based on semi extensive reading on this forum, I'm leaning towards a 24V battery bank, with an AH rating of 700Ah, I'd like to use solar power to power just my bedroom and the two pumps for now, and a desired wattage of panels to sufficiently and safely charge/power desired battery bank and either a 3 or 4kW pure sine wave inverter

    And the theoretical results, where can i find a resource to educate me on the different solar power calculations like the formulas you demonstrated earlier, and also, what do you mean by the 50,000 foot design?
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    50,000 foot view is from a jet airliner (you see the roads, housing patterns, whole city at the same time--Slang). Don't get "tunnel vision" when looking at wiring up a battery bank just yet.

    Just ask about the equations--Where we get the derating factors, why we choose 2 days and 50% battery sizing vs something else etc.

    Many are just rules of thumbs that work well for us (experience). Basically, very quick to get a basic/functional/reliable design in a few minutes.

    And the rules of thumbs are just starting points. If you have "unusual" needs--Then things can be changed/adjusted to better support your needs.

    This thread has lots of links to books and other websites if you wish to read more.

    http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenGen XVIIIGreenGen XVIII Registered Users Posts: 15
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    Thank you so much Bill, your input has been invaluable, i'll start reviewing the material n posts, and should design a more practical system within a week. Can i email you my revised plans for a critique?
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker
    BB. wrote: »
    .

    Pretty difficult to make general suggestions (very broad subject--energy conservation). Instead, look at your loads and decide which one (or several) to attack first.

    If you already have a laptop that uses 0.3 kWH per day and a 5 watt cell phone charger--And a pair of 3/4 HP pumps--Look at the pumps first.

    Also peak current and total WH (or kWH per day) are sort of two different problems.

    For example, a microwave uses 1,500 Watts peak, but only 20 minutes per day:

    1,500 Watts * 1/3rd hour per day = 500 WH per day
    30 watt laptop * 8 hours per day = 240 WH per day
    5 watt USB Charger * 4 hours = 20 WH per day
    22 watts of LED lighting * 4 hours = 88 WH per day
    750 Watt pump * 6 hours per day = 4,500 WH per day

    750 Watt pump may take 2-3 kWatts starting surge...

    So--Figure out your present power needs--Cost of larger Off Grid power system vs cost of "new energy conservation appliances/pumps" and see what works out for you. In general, the costs of reduce power needs can be much less than the costs to increase the size/long term maintenance of your off grid power system.
    -Bill

    Hi GreenGen ... The council of trying to determine just what your system will need to do has been given several times in this Thread.

    If you are able to slow down a bit, and take some time to consider what your system really needs to do, including measuring loads of those things that you now have that will be used on the new system, you will be much better off.

    Trying to choose hardware to provide power, when the amount of power needed, when it will be needed, the peak power, etc are not yet known in real terms can result in having some expensive items that may not really be appropriate for your actual needs

    This data need not be perfect, but actual data is the best starting point for any engineering project, IMO.

    Have Fun, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    GreenGen,

    I have sent you a PM with my email address.

    As you get better information on your loads--We can help some more here too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Advice on this system and can an MC4 connector connect directly to a circuit breaker

    green.....
    I would say that bill should be your hero due to the amount of time and follow through and work in typing good responces. I do think however, that you miss in two ways if you deal stricly with bill. It seems he doesn't mind as he gave you his email. One of the ways you miss out is when you present what you come up with, there may be someone here that sees what bill might miss (although I don't think he misses much). One of the other ways you lose is by other members not being able to learn with you as you move further. Bill has did most of the work so maby we don't deserve to know everything or maby he is just that much smarter then guys like me.. I do understand that sometimes it may be easier to send things through email then to load them on a forum. I do like seeing how poeple come up with what they need to make stuff work and I also like seeing the answers to guys like us who may not have the knowlage of the experts like bill. I keep watching his responces cause they help me also and someday I may need to help some one else from what I learned here.

    These are just my thought for your consideration and also if you both feel more comfortable doing it by email I don't want to be in the way.
    Thanks
    gww
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