Installing Solar Panel System on my Van - Question about grounding

stephsteph Registered Users, Users Awaiting Email Confirmation Posts: 4
Hi,

I have built a sweet DIY camper van out of a chevy 1500. Last thing to do is set up the pv solar system off of which we plan to run the fridge, fan and charge phones. 
I am really confused about grounding the system! What is required to make the system safe? This is what we have:

2 x 100 W solar panels
30 amp charge controller
1500 W inverter 
190 ah 12 V battery 

The DC system will be all 12 V

I do not have a super strong understanding of electrical systems and reading too many different opinions people have of setting up a system like mine has led me to become very confused. 

As far as I know I would want to ground the battery and the inverter to the chassis, however, we have a modified sine wave inverter, and I've been told that it is a bad idea to ground a modified sine wave inverter. 

Comments

  • mvasmvas Registered Users Posts: 359 ✭✭✭
    edited June 2017 #2
    Yes, you can ground the case of your Modified Sine Wave inverter. 
    The real issue is - "Bonding" the Neutral Wire and the Ground Wire together, like we always do in the Main AC Panel.
    Does your inverter have AC Outlets?
    Does your inverter's case have a location labeled GND?
    Do you have a fuse or CB, too ?

    How may KWH does fridge consume daily?
  • mike95490mike95490 Solar Expert Posts: 8,500 ✭✭✭✭✭
    A fridge should not be run off of a mod-sine inverter.  Noise, heat and extra power loss are main reasons.   The motors run cooler on pure sine, and therefor, less heat to dump.
    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 ,

  • EstragonEstragon Registered Users Posts: 4,303 ✭✭✭✭✭
    Does the van have a "shore power" connection to plug into an external AC source?
    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
  • mike95490mike95490 Solar Expert Posts: 8,500 ✭✭✭✭✭
    No one else said it, so I will.
     Mod Sine inverters should not be "grounded"   They generate each leg +- 60VAC generally referenced to the - battery terminal. 
    If you ground them, you are forcing the + battery terminal to be at 60V +Vbatt and can get a shock.
      Someone say I'm wrong on this.........
    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 ,

  • stephsteph Registered Users, Users Awaiting Email Confirmation Posts: 4
    mvas said:
    Yes, you can ground the case of your Modified Sine Wave inverter. 
    The real issue is - "Bonding" the Neutral Wire and the Ground Wire together, like we always do in the Main AC Panel.
    Does your inverter have AC Outlets?
    Does your inverter have a location labeled GND?
    Do you have a fuse or CB, too ?

    How may KWH does fridge consume daily?
    Where would I ground the case? 
    The inverter has 2 AC outlets, no location labelled ground. All it has are the two terminals coming from the battery and the 2 AC power outlets. I will have a fuse or CB on the positive side between the battery and the inverter. 
  • BB.BB. Super Moderators, Administrators Posts: 29,825 admin
    Well... To be very clear, you cannot ground reference both the negative battery terminal (typical) and the "white" neutral on the AC output (typical for North American 120/240 VAC split phase power systems). If you were to ground reference both the DC input and AC output, that creates a short in the AC inverter and will let out the magic smoke.

    Most (almost all?) MSW AC Inverters do not have an isolation transformer between the DC input and the AC output.

    Most (almost all?) TSW/PSW AC inverters have transformer isolation and you can ground reference the Battery bank negative terminal and the AC "white wire/neutral" output and all is fine.

    The (usual) correct way to ground reference MSW inverters is to negative ground the battery bank (as done in vehicles) and to ground the msw inverter's case (usually a case ground screw or stud). And the AC output will be left floating (no ground reference).

    As Mike says, you will now have two "hot" AC inverter wires (not one hot and one neutral as used in North American wiring). As long as your loads do not ground reference the neutral (never done any more, very old appliances may tie case ground to the "neutral blade" such as a mixer), all will usually be fine.

    You may find some issues with a few appliances (possibly florescent lights may not start as well, certain spark ignition systems used on stoves/hot water heaters/etc. may not flame sense correctly because of AC power/ground issues).

    And the problem that some devices (induction motors, some "cheap" AC power bricks/wall transformers) may run hot (or even fail) with MSW inverters. It is difficult to tell which devices will fail or not... Fortunately, it is becoming more rare to run across the portable drill type battery charger that "dies" when connected to MSW inverters.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • stephsteph Registered Users, Users Awaiting Email Confirmation Posts: 4
    Estragon said:
    Does the van have a "shore power" connection to plug into an external AC source?
    No it does not.


  • mvasmvas Registered Users Posts: 359 ✭✭✭
    edited June 2017 #9
    mike95490 said:
    No one else said it, so I will.
     Mod Sine inverters should not be "grounded"   They generate each leg +- 60VAC generally referenced to the - battery terminal. 
    If you ground them, you are forcing the + battery terminal to be at 60V +Vbatt and can get a shock.
      Someone say I'm wrong on this.........
    You are wrong.
    Already answered in message #2.
    The inverter's case must be grounded for safety.
    The National Electric Code requires the metal case to be grounded.
    Tell me, they are wrong.
    Depending upon where he lives, he might be required to pull a permit and get an inspection.

    What you say about "... each leg being +/- 60 VAC with reference to the (-) battery terminal ...",
    may or may not, be true depending upon the internal design of the inverter. You don't really know.
    We do not want to BOND the Neutral (white) wire of the AC Output to the Ground (like inside the Main AC Panel).
    The OP asked about GROUNDING the inverter = YES.
    You are talking about BONDING the AC Neutral to the Ground - not the question asked by the OP.
    In your reply, you  have confused proper Grounding, with proper Bonding - two different connections.
    And if the MSW Inverter only has AC Outlets then he can't even bond the neutral to the ground.

  • mvasmvas Registered Users Posts: 359 ✭✭✭
    Quote from the Xantrex Modified Sine Wave Inverter manual ...

    "...
    Grounding Locations
    You must connect the chassis ground stud to a grounding point—usually the vehicle’s chassis—using recommended copper wire (if insulated then green insulation with or without one or more yellow stripes) or larger. 
    ..."
  • mcgivormcgivor Solar Expert Posts: 3,205 ✭✭✭✭✭
    edited June 2017 #11
    mvas said:
    Quote from the Xantrex Modified Sine Wave Inverter manual ...

    "...

    Grounding Locations
    You must connect the chassis ground stud to a grounding point—usually the vehicle’s chassis—using recommended copper wire (if insulated then green insulation with or without one or more yellow stripes) or larger. 
    ..."

    Many, let's say, less expensive inverters, wether PSW or MSW, do not have provision for a ground wire,  perhaps not ULC listed and so forth, so if no grounding point is provided, as I believe is the case with @steph , should he therefore modify the inverter and install a grounding point? and if so, what reference dose the output have with respect to said ground, unless the battery negative is grounded and if so is the chassis connected to the negative battery terminal negating the need for a separate ground wire, just curious as I've seen such inverters.
    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: 4,303 ✭✭✭✭✭
    @mcgivor - I have two such inverters. One is a 300w that was on my boat when I bought it, the other a 1000w cheapie from C.Tire that we used when we only had generator and a couple of golf carts. Both are MSW. Neither has provision for case ground externally. They have duplex AC outlets, and the little one has alligator clips for 12vdc. They aren't designed to be installed permanently.

    I haven't opened one up, but I assume case grounding is handled internally.
    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
  • stephsteph Registered Users, Users Awaiting Email Confirmation Posts: 4
    mvas said:
    mike95490 said:
    No one else said it, so I will.
     Mod Sine inverters should not be "grounded"   They generate each leg +- 60VAC generally referenced to the - battery terminal. 
    If you ground them, you are forcing the + battery terminal to be at 60V +Vbatt and can get a shock.
      Someone say I'm wrong on this.........
    You are wrong.
    Already answered in message #2.
    The inverter's case must be grounded for safety.
    The National Electric Code requires the metal case to be grounded.
    Tell me, they are wrong.
    Depending upon where he lives, he might be required to pull a permit and get an inspection.

    What you say about "... each leg being +/- 60 VAC with reference to the (-) battery terminal ...",
    may or may not, be true depending upon the internal design of the inverter. You don't really know.
    We do not want to BOND the Neutral (white) wire of the AC Output to the Ground (like inside the Main AC Panel).
    The OP asked about GROUNDING the inverter = YES.
    You are talking about BONDING the AC Neutral to the Ground - not the question asked by the OP.
    In your reply, you  have confused proper Grounding, with proper Bonding - two different connections.
    And if the MSW Inverter only has AC Outlets then he can't even bond the neutral to the ground.

    Thank you for the clarification. I am grounding the case.
  • bunker80bunker80 Registered Users Posts: 2
    I have a similar system; however, the inverter does have provisions on the case for grounding. It says to only mount to a “negatively ground system.”

    Please confirm that I need to do the following.

    1. Ground the batter bank to the chassis or frame of the van with the negative batter terminal.

    2. Ground the inverter to the chassis or frame of the van.

    In other words, please confirm I need to do BOTH.

    Thanks!

    Ryan
  • BB.BB. Super Moderators, Administrators Posts: 29,825 admin
    Yes, that is the normal grounding method.

    You want negative grounds from battery to chassis of vehicle.

    And you want metal electrical boxes to be grounded to chassis. If there is a short from 12 vdc + to the metal inverter box, you want a return path of good electrical connections to pop the inverter fuse/breaker and kill the power.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,500 ✭✭✭✭✭
    I just want to repeat a caution regarding Mod-Sine inverters and grounding. 
     ( what's the best way to state it ? )
    The inverter output "floats" and there is NOT a Line and Neutral output, if one of the high voltage AC leads gets grounded via a conventional electrical panel, the vehicle chassis will be connected to 50% line voltage (generally +60V or -60V )
    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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