New Here - Installing Solar System w/Inverter for my trailer

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Hi everyone

I'm very new to the solar/ inverter world, but have been trying to study.

I have a trailer right now that currently has an Onan 5500 generator with a 50 amp transfer switch for shore power.

I am having a professional install (4) 130 watt Kyocera Solar panels on my roof, with Magnum 4024 Pure Sine Inverter, Automatic Gen Start, and Blue Sky Solar Boost Charge Controller, powered by 6 volt AGM 220ah batteries.

My question is, do I need to install a 3 way Automatic Transfer switch now which will switch between inverter, generator and shore power ( http://www.rvparts.com/index.php?a4c04ca134b2150748cdfa8cc8402312a5c05f615cb2ee088daa10e2ad8495c30c06a81491fc446f0be0fc7d2d2067bf1d89224a34db8ddab92b4cc9ff52ce6cdb2fbf93b70772f3092b4cc9ff52ce6cdd260ff2d716a9893417fbd2a30509af1 ) ... or can I somehow keep the Automatic 2-way transfer switch I have now which is just for generator and shore and just turn the inverter on and off when I need it ...

Thanks for your help if you have any suggestions :)
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Comments

  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    #2
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Pez
    Your installer is the person who should answer that question for you. But in general, most top of the line inverters, (I'm not familiar with the Magnum) have a transfer switch built in. You will still need the 2 way switch to keep shore power and generator power seperate, but from there the power will go to the inverter and pass through to your loads. If there is no power from shore or gen then the inverter will use battery power to supply your AC loads, and it will do this automatically, no switches to flip or turn.
    Hope this helps,
    Larry
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: New Here - Installing Solar System w/Inverter for my trailer

    8-) Thanks so much rplarry for the reply  - the Magnum 4024 does have an automatic transfer - I'm not sure why my installer guy couldn't decide if we needed the 3-way transfer switch, maybe he was tired when I asked him last night... ahhh, that's good news though from you, I won't have to spend $350 more now :) Thanks again, Marie
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  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    #4
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Pez
    Well that is good news. Again your installer is the person to rely on, he knows more about your system than anyone on a forum.
    Larry
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    Re: New Here - Installing Solar System w/Inverter for my trailer
    rplarry wrote:
    Pez
    Again your installer is the person to rely on, he knows more about your system than anyone on a forum.

    MAYBE.

    I'm not sure if I would want an installer that did not know if I needed the $350 switch.
    Of course it's needed if it cost $350 !!
    /sarcasm OFF
    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 ,

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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: New Here - Installing Solar System w/Inverter for my trailer
    mike90045 wrote:
    rplarry wrote:
    Pez
    Again your installer is the person to rely on, he knows more about your system than anyone on a forum.

    MAYBE.

    I'm not sure if I would want an installer that did not know if I needed the $350 switch. 
    Of course it's needed if it cost $350 !! 
        /sarcasm OFF

    LOL - Sarcasm appreciated, keeps the riffraff in line  :-P   ... I did wonder why he couldn't give me an answer, at least it wasn't because he was trying to make me buy the $350 switch from him, I was going to order it on my own over the internet if I needed it.
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: New Here - Installing Solar System w/Inverter for my trailer

    :-D I had my solar panels installed on the top of my 7' x 12' trailer this week! I am super happy to announce that I used 2 KW of free power from the sun for the last couple of days and it was so nice and quiet without the generator :) ... does happy dance, heehee.

    Here is a pic taken from my balcony of the trailer top ...

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: New Here - Installing Solar System w/Inverter for my trailer

    looks real good. enjoy it, but you may wish to put something to deter theft of your pvs. after all, that is alot of money on your roof. maybe oddball hardware needing special tools for removal like http://search.store.yahoo.com/cgi-bin/nsearch?query=hardware&vwcatalog=wind-sun&.autodone=http%3A%2F%2Fstore.solar-electric.com%2F and maybe an alarm.
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #9
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Pez,

    Look GREAT! I hope you'll come back in a few weeks with your performance observations. niel's suggestion about the anti-theft hardware is a good one, BTW.

    Enjoy! 8-)
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #10
    Re: New Here - Installing Solar System w/Inverter for my trailer

    :-) Thank you for the suggestions niel and crewzer about security - and I'll keep you posted but I'm sure I'll have more questions to bug you with regarding the Blue Sky Charge Controller and battery and temperature stuff to optimize. :-P
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  • System2
    System2 Posts: 6,290 admin
    #11
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Hi everyone, so far, of course loving the solar and inverter setup ... couple of questions though ...

    1. Do I need a fuse between the Blue Sky Controller and the battery bank - I was looking through an RV electrical book and noticed there was a fuse in their illustration, but my installer didn't put one - is my system dangerous right now?

    2. If I turn my generator on and the charger starts up in the Magnum Inverter, does it confuse the Blue Sky Charge Controller with incorrect battery voltage readings ( and vice versa does the Controller confuse the Magnum charger), hence, incorrect charging? Should I just turn off the Magnum Charger?

    Thanks again for your time,
    Marie :-)

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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #12
    Re: New Here - Installing Solar System w/Inverter for my trailer
    1. Do I need a fuse between the Blue Sky Controller and the battery bank...

    Your controller should indeed be protected by a fuse and/or circuit breaker. Check your controller's owner's manual for recommendations.
    2. If I turn my generator on and the charger starts up in the Magnum Inverter, does it confuse the Blue Sky Charge Controller with incorrect battery voltage readings ( and vice versa does the Controller confuse the Magnum charger), hence, incorrect charging? Should I just turn off the Magnum Charger?

    The two chargers should be compatible in general. If one charger maintains the battery voltage higher than the other charger's setting, the lower voltage charger will probably just stop delivering charge current.

    HTH,
    Jim / crewzer
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #13
    Re: New Here - Installing Solar System w/Inverter for my trailer

    i fully agree with jim on these 2 points. do note that any wires going to or from your batteries has the potential to short if something goes wrong. the batteries could discharge a high amount of current at their rated voltage with enough potential to weld and sometimes cause a fire. this could also lessen the lifespan of your batteries or ruin your batteries altogether. it is usually sufficient to fuse or breaker one polarity as the circuit would be in series in that the current will always make its way back to the other polarity.
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  • System2
    System2 Posts: 6,290 admin
    #14
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Thank you crewzer and niel for your advice ... I'll be getting my installer to put a fuse in ... I looked in the Blue Sky Manual and though their illustration didn't show a fuse, I called a tech at Blue Sky and he said the NEC code says it's absolutely necessary... so many things to learn :-o
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #15
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Pez,

    Something's not right here...  :? For example, the Blue Sky 3024i manual states: "...connect only to a circuit provided with 40 amperes maximum branch-circuit over current protection." (page 7), and the wiring diagram on page 8 shows a 40 A fuse in the battery (+) cable.

    Which controller do you have?

    Regards,
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #16
    Re: New Here - Installing Solar System w/Inverter for my trailer

    I have the Blue Sky Solar Boost 50L ...
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #17
    Re: New Here - Installing Solar System w/Inverter for my trailer

    Pez,

    Unfortunately, the "Setup and Wiring Diagram" (pg. 14, Figure 3) in the 50L's manual doesn't show a fuse or circuit breaker. However the following warning is included on page 13:

    "WARNING: Read, understand and follow the Important Safety Instructions in the beginning of this
    manual before proceeding. To reduce the risk of fire, connect only to a circuit provided with 60 amperes
    maximum branch-circuit over current protection installed and wired in accordance with National Electrical
    Code, ANSI/NFPA 70. To reduce risk of electric shock, remove all sources of power, PV and battery before
    installing. Adjustments or connections other than those shown in Figure 3 void the limited warranty."

    So, it seems that Blue Sky is recommending a maximum 60 A fuse or circuit breaker. That's sort of in-line with the NEC 690.8, which, if I have interpreted it correctly, requires for overcurrent protection rated at 125% of maximum current, or 100% if the overcurrent protection device is rated for continuous duty at 100% of its rating. 50 A x 125% = ~63 A.

    Should you decide to go the circuit breaker route, you'll need a circuit breaker rated for DC use. These can be expensive and/or hard to find. An inexpensive but safe solution might be to use a Square D series QO breaker rated for 60 A. Although labled for AC applications, they are DC rated to 48 V. These breakers, and small subpanels to house 'em, are readily available from places like Home Depot. However, for a 60 A circuit breaker, you may have to buy a "double breaker" model, but just use one side.

    HTH,
    Jim / crewzer
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #18
    Re: New Here - Installing Solar System w/Inverter for my trailer

    pez,
    firstly, see what bobboyce had to say in this thread. http://www.wind-sun.com/smf/index.php?topic=1364.0
    secondly, shame on bluesky for not including the fuse on their diagram. by this omission they also imply that utilizing the fuse could be interpreted without reading all as a violation of their warranty. most use the fuse or circuit breaker on the positive leads and this should be done as close to the battery as possible as this is not a protection for the controller, but one for the battery against shorts. now your pvs are rated at 7.39amps each so 7.39x4 is 29.56amps. multiplying by 1.25 gives 36.95amps. this means if you find a 40 or 50amp fuse or circuit breaker that you could use it instead of the 60amp that is the maximum allowed. i'd go minimumly with the 50amp as you could get that rare edge of cloud event coupled with the mppt boost that would make a 40amp blow. also note that the unit is not supposed to output greater than 50amps anyhow even with more current being inputted.
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #19
    Re: New Here - Installing Solar System w/Inverter for my trailer

    I think niel makes a good point about tailoring your circuit breaker to your actual system size. However, since your system is 24 V nominal and not 12 V, the design current calculation should probably be something like 8.02 A Isc per string x 2 strings = 16.04 A x 125% = ~20.05 A.

    Allowing for the controller's MPPT feature, I suspect you could get by with a 25 or 30 A breaker.

    HTH,
    Jim / crewzer
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #20
    Re: New Here - Installing Solar System w/Inverter for my trailer

    oops my mistake as i was thinking in 12v terms. thanks for catching it jim.
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  • System2
    System2 Posts: 6,290 admin
    #21
    Re: New Here - Installing Solar System w/Inverter for my trailer

    I love you guys! I'm so thrilled with all of your extensive knowledge and the facts and figures to back up your advice so I don't have to trust you blindly. I guess my installer isn't the most knowlegeable on NEC, not good I know, but he's a mobile RV Tech who's been around to help me through the years and I trust him otherwise in general... as long as you don't mind me asking you all of these questions, I hope I can keep checking in every once in a while to make sure I'm up to code, I'd be very grateful.

    So I'll go with the 30 A breaker or maybe a 30 A Class T fuse? ( OK, I agree, shame on Blue Sky for not including it in the diagram  :-P )

    And yikes about BobBoyce's trailer  :-o ... I have a motion alarm already on my trailer, but I think I'll get the special screws too, not that that would help with someone putting a rope around my trailer, at least I live in a gated community.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #22
    Re: New Here - Installing Solar System w/Inverter for my trailer

    30amps is fine and as jim said so is 25amps. 25amps may be a more common value and would trip faster in the event of a short.
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