Solar Circuitry Diagram HELP

therookie

New member
Hello! First post during my first conversion.

I just made my first ever circuit diagram!! I was hoping an electrician superhero on the forum could come to my rescue and proofread it please !!





Solar Wiring Diagram.jpg



I am feeling pretty good about it, excited to make it a reality.

Open to suggestions/critiques on wire size, connections, fuses, components, etc. I have already purchased all components except for the wires.

Specific questions:
One area I am confused on is the ground. Does my single ground from the negative bus bar work here? What size wire is necessary to ground from the bus bar in this system? I feel it should match the largest input wire... not sure.
Finally will it be easy to add an alternator connection to this system down the road ?

Thank you for taking the time to study my diagram and give me some tips! Super appreciated.

~ The Rookie
Sprinter 2013 144" 2500
 

autostaretx

Erratic Member
Good drawing ... i would suggest adding the expected (major) wire lengths as well.
Your wire sizing looks OK ... in fact, the 4 awg from solar controller to battery may be thicker than needed, if it's a short distance.

The term "ground" is often mis-used (be me, certainly) ... since you're not depending upon the Sprinter's frame to reach its alternator, you really don't have to tie your system negative to the frame.

You will (probably) find that the Inverter has a "case ground" (using a wire that only matches the 120 vac side gauge) ... that's to protect you if something inside the invert box goes weirdly wrong ... so they're only trying to grab the high-voltage consequences.

You probably want to add a switch/breaker/local fuse so that you can disconnect the panels from the MPPT controller when you need/want to work on things ... it would be a pain to have to crawl up on the roof to disconnect that in-line fuse.
Controllers usually want the battery connected *first* before the panels are connected ... and panels removed first before disconnecting the controller from the battery.

--dick
 

therookie

New member
Good drawing ... i would suggest adding the expected (major) wire lengths as well.
Your wire sizing looks OK ... in fact, the 4 awg from solar controller to battery may be thicker than needed, if it's a short distance.

The term "ground" is often mis-used (be me, certainly) ... since you're not depending upon the Sprinter's frame to reach its alternator, you really don't have to tie your system negative to the frame.

You will (probably) find that the Inverter has a "case ground" (using a wire that only matches the 120 vac side gauge) ... that's to protect you if something inside the invert box goes weirdly wrong ... so they're only trying to grab the high-voltage consequences.

You probably want to add a switch/breaker/local fuse so that you can disconnect the panels from the MPPT controller when you need/want to work on things ... it would be a pain to have to crawl up on the roof to disconnect that in-line fuse.
Controllers usually want the battery connected *first* before the panels are connected ... and panels removed first before disconnecting the controller from the battery.

--dick
Hey thanks for the compliment Dick! I worked hard on this drawing.
Thanks for clearing up ground for me. I am leaning towards a floating system unless there are any advantages to grounding? Most responses are along the lines of "it's not totally necessary" but if it's the safest catastrophic discharge point maybe I should do it anyways.
And for the solar panels fuse... I could move that in-line fuse in closer to the house batteries; I also moved my solar controller connection to a position before the main system kill switch, just after the battery terminal fuse, so that I could hit that switch and the whole system loses power. Is my logic sound here?

You're a legend, thanks for your help.
 

OrioN

2008 2500 170" EXT
Dude I'm gonna need it
In all seriousness, I have two extinguishers on board. One is a CO2 type that works by starving the fire and doesn't leave a chemical & corrosive residue that is the kiss of death for electronic equipment or even engine seals. The other is the less expensive chemical type for outside fires or other folks to use.
 

therookie

New member
In all seriousness, I have two extinguishers on board. One is a CO2 type that works by starving the fire and doesn't leave a chemical & corrosive residue that is the kiss of death for electronic equipment or even engine seals. The other is the less expensive chemical type for outside fires or other folks to use.
smart. ill check out the CO2 type on amazon
 

autostaretx

Erratic Member
Hey thanks for the compliment Dick! I worked hard on this drawing.
Thanks for clearing up ground for me. I am leaning towards a floating system unless there are any advantages to grounding? Most responses are along the lines of "it's not totally necessary" but if it's the safest catastrophic discharge point maybe I should do it anyways.
If you're not attached to shore power, you're "floating free" from earthing anything. So even if the vehicle frame became "hot", the (frequently fatal) danger of having your body become a conductor when one foot's (or arm on the grab bar) is in the van and the other is on the wet grass ain't going to happen.
And for the solar panels fuse... I could move that in-line fuse in closer to the house batteries; I also moved my solar controller connection to a position before the main system kill switch, just after the battery terminal fuse, so that I could hit that switch and the whole system loses power. Is my logic sound here?
Well .... i did give that a thought before i wrote my first reply.
With the controller on the battery side of the switch, you can be solar-charging the batteries while you've got all of the loads disconnected for servicing (etc). Which i thought was a Good Thing.
If the beefy terminal fuse ever pops, and you open your main switch, everybody is isolated from each other, which is good.

--dick
 

Kevin.Hutch

2011 Mercedes 313 906
Well thought out mud map, I would be inclined to remove the solar fuse altogether as it is only another point of failure, the panels and wiring should stand a complete short circuit. All you need is a way of disconnecting the solar panels from the regulator and I find the regulator screw terminal more than adequate for this.

I agree with the dropping the chassis earth connection, when you connect the alternator it will come with the vehicle chassis ground and I would not advocate two grounds, as none of your house load should be chassis return. Only use the chassis return as a mains safety return when on shore power as this is the only time a GFCI will protect you.

As mentioned rough estimate of cable lengths would help qualify wire sizing.
 

therookie

New member
Well thought out mud map, I would be inclined to remove the solar fuse altogether as it is only another point of failure, the panels and wiring should stand a complete short circuit. All you need is a way of disconnecting the solar panels from the regulator and I find the regulator screw terminal more than adequate for this.

I agree with the dropping the chassis earth connection, when you connect the alternator it will come with the vehicle chassis ground and I would not advocate two grounds, as none of your house load should be chassis return. Only use the chassis return as a mains safety return when on shore power as this is the only time a GFCI will protect you.
Why are the panels more capable of handling a short ?
And I checked my2000w inverter instructions and it requires a ground to chassis.Will the alternator's ground cover it or will I needan AC ground and a DC ground?
 

autostaretx

Erratic Member
Why are the panels more capable of handling a short ?
And I checked my2000w inverter instructions and it requires a ground to chassis.Will the alternator's ground cover it or will I needan AC ground and a DC ground?
You're confusing "ground" (earthing) with "negative connection"
As i wrote above, the "ground to chassis" has *nothing to do* with the current-carrying portions of your circuit.

The panels-to-controller, controller-to-battery, battery-to-12vloads, battery-to-inverter, inverter-to-ACloads and the loads themselves can all be completely free of a connection to the Sprinter's frame and/or its negative current system (which is the frame and a bunch of brown wires).
((added: except the 3rd pin of the 120vac sockets... they'll probably be tied to the inverter's metal box.))

Only one wire *really* wants to tie to the frame, and that is the outer box ground of the inverter's metal box.
With an AWG 10 (or thereabouts) wire. (that's "ten" not "one-naught").

You certainly could, if you wished, connect your house 12v negative to the frame, and you'd have to do that if you wanted to use the Sprinter's alternator to help charge your batteries (unless you used a DC-to-DC charger as the "bridge").
But that's a "choice", not a necessity. Kevin's a fan of not making that connection.
But "that connection" has nothing to do with the inverter case grounding/earthing/framing.

--dick
 

Kevin.Hutch

2011 Mercedes 313 906
Why are the panels more capable of handling a short ?
And I checked my2000w inverter instructions and it requires a ground to chassis. Will the alternator's ground cover it or will I need an AC ground and a DC ground?
1. It is not that the solar panels are more capable of handling a short circuit it is just that there is no side effect of them supplying there maximum current that a short circuit would create and the cable should be specified to meet this, so being able to isolate them is the only need.

2. The inverter spec says connect its chassis to ground but the ground will only be present when the shore power cord is connected, as the vehicle is isolated from ground by it's rubber tyres. If the inverter feeds a GFCI breaker then it may have a neutral connection where one of its live wires is connected to the ground connection, provided all the exposed metallic components in the van are bonded together this may give a level of personal protection. However mostly the only exposed surface in a van, such as a stainless sink, is not bonded , aluminium framed cabinets may be but not reliably, so an isolated system with no active/hot and neutral/ground is actually safer. Most GFCI breakers rely on residual current (ie a current differential between the live wires, going presumably to earth) so if there is no neutral earth bond there is no possibility of residual current.

3. No there is no such thing a AC ground vs DC ground or earth. Ground is a low impedance connection to mother earth, mostly via an earth stake and regularly provided in a house but rarely found in any mobile accommodation, unless it is fed by (multiple earth neutral) mains power with an earth pin.

Just to get my head around the schematic I redraw it and added the inverter earth plus the 12v power for the shunt circuit.Sprinter Electrics.JPG
 
Last edited:

RVBarry

Well-known member
The inverter spec says connect its chassis to ground but the ground will only be present when the shore power cord is connected, as the vehicle is isolated from ground by it's rubber tyres. If the inverter feeds a GFCI breaker then it may have a neutral connection where one of its live wires is connected to the ground connection, provided all the exposed metallic components in the van are bonded together this may give a level of personal protection. However mostly the only exposed surface in a van, such as a stainless sink, is not bonded , aluminium framed cabinets may be but not reliably, so an isolated system with no active/hot and neutral/ground is actually safer. Most GFCI breakers rely on residual current (ie a current differential between the live wires, going presumably to earth) so if there is no neutral earth bond there is no possibility of residual current.
Hi if you're talking about no shore power, I think I agree with you, but with shore power, I worry about this:

if the vehicle frame became "hot", the (frequently fatal) danger of having your body become a conductor when one foot's (or arm on the grab bar) is in the van and the other is on the wet grass
 

Kevin.Hutch

2011 Mercedes 313 906
Part and parcel of connecting shore power automatically means that the ground wire from the Van is connected to mother earth via the cable as it is a requirement that the Van body is bonded to the earth pin. This is mandated by electrical authorities as the shore power comes with a active/hot and neutral/earth (MEN) connection so this clearly will connect the Van body to the earth and the GFCI (RCD) can sense up to a 30mA current differential (less than fatal) before it trips.

If you want the same protection in an "isolated system" you will have to replace the GFCI (RCD ) with an RVD (Residual Voltage Device) that detects and trips when over 40v between either live wire and the earth or van frame is detected.

This video highlights the issue https://www.rvdsafe.com.au/inverters/
 

RVBarry

Well-known member
Part and parcel of connecting shore power automatically means that the ground wire from the Van is connected to mother earth via the cable as it is a requirement that the Van body is bonded to the earth pin. This is mandated by electrical authorities as the shore power comes with a active/hot and neutral/earth (MEN) connection so this clearly will connect the Van body to the earth and the GFCI (RCD) can sense up to a 30mA current differential (less than fatal) before it trips.
Hi,
Where should these GFCIs be?
At the shore service outlet?
In the shore power breaker in the van?
In the transfer relay?
In the inverter?

I notice the Blue Sea shore breakers do not have any protections other than a single LED for polarity check.

I'm planning on a Victron Multiplus, or Magnum or Xantrex Inverter/Charger/Transfer device, with BlueSea breakers, fwiw.

Thanks
 

Kevin.Hutch

2011 Mercedes 313 906
A GFCI (RCD) includes a breaker and replaces the mains circuit breaker.

It is installed as close as practical to the inlet socket with direct connection between the earth pin and the steel of the chassis/body of the van.

In Aus It is mandated by law in mobile mains powered vehicles.
 

ctmcdaniel

Cross Member
Howdy


If you use this battery instead of the battleborn and you can eliminate the shunt and the battery monitor plus it has an internal heater for low temperature operation. The lifeblues have Bluetooth and a simple app that tell you battery state and amps and amps out. I have these batteries in a travel trailer and it's worked out great I also put them into other friends builds and again they worked out just great.
 

RVBarry

Well-known member
A GFCI (RCD) includes a breaker and replaces the mains circuit breaker.

It is installed as close as practical to the inlet socket with direct connection between the earth pin and the steel of the chassis/body of the van.

In Aus It is mandated by law in mobile mains powered vehicles.
Thanks...
Blue Sea only offers ELCI breakers, e.g.
I need to research if ELCI would be appropriate for an RV; there's a thread at https://sprinter-source.com/forums/index.php?threads/33053/

If anyone has any other recommendations for 120V shore GFCI breakers, they would be welcome.
 

autostaretx

Erratic Member
One source of confusion in this thread is that we're referencing "therookie"'s wiring diagram (no shore power), but RvBarry is asking about a situation with a shore power connection.

It's always a good idea to check a campground's power kiosk to verify that their wires are properly arranged.
You can't always trust that they've got the hot, neutral and ground going where they should, or that someone's casual fiddling with the kiosk hasn't compromised a wire ... i was at one where the neutral was pinched by the box's metal work, turning it into a ground ... which is "functionally" OK ... but it was only a 50/50 chance that it hadn't made the box hot by doing it to the hot wire.
It's also possible to "lift" a neutral to some potential above ground by asymmetric loads on someone's 50 amp hookup.

--dick
 

Kevin.Hutch

2011 Mercedes 313 906
ELCI (Equipment Leakage) & GFCI ( Ground Fault Circuit Interrupters), are terms that apply to Residual Current Detection devices that include a circuit breaker and simply sense a residual current differential between one live wire and another then trip a circuit breaker.

RCD is of no consequence if installed in an Isolated (no neutral/earth connection) system such as most inverters and gensets. For electrolysis reasons marine gensets/inverters should never have live wires grounded. An alternate path does not exist without two faults, a residual current can only exist if one live wire is connected to ground, then the other becomes active with respect to ground waiting for a second fault to create circuit.

Neutral/earth bonding is the case for a myriad of reasons in domestic and fixed wiring situations on land where a quality earth connection can be guaranteed.

Blue Sea imply that the ABYC specified Type A GFCI at 5mA applies to all GFCI units. GFCI/EFCI/RCD’s can come in varying residual current ratings.

Due to normal earth leakage in electrical appliances 30mA is used to protect complete circuits as 30mA is not considered lethal. 10mA and 5mA GFCI’s are defined as preferable in wet environments, requiring less appliances be serviced by them to prevent nuisance tripping.

In a conventional RV the expected “normal” earth leakage of appliances is minimal and a 30mA protection is considered all that is necessary.

Polarity detection is to verify that the wrong pin is the shore power neutral or electrically connected to ground, it may not detect if no live wire is connected to ground.

If the active from shore is connected to the metalwork on a boat the surrounding water can be a death trap especially fresh water, just the same as an RV's bodywork can be, but in an RV it requires that you touch a conductive part.

In ground isolated systems the preferred method is an RVD Residual Voltage Detector that excludes any source of power becoming lethal in a ground fault situation by detecting a 40v+ between live wires and ground reference wiring.

Conclusion: 30mA GFCI protection at the RV mains input, no earth neutral within an RV with, is the minimum but this does not preclude receptacle 5mA GFCI if regular shore power is in use.

Remembering without a quality earth connection, any type of RCD is superfluous in detecting ground faults.
 

Top Bottom