This Right? Wiring Diagram for 400w Solar System

[thiel]

All,

I think I've got this ALMOST figured out, but I wonder if you could look at this image and tell me what's wrong?

In particular, I am wondering whether I need to home-run the tongue jack negative cable all the way back to the shunt or whether using a lug as shown will work. (Right edge of the picture).

... but I could use a double-check on the rest as well! Thanks!


THANKS EVERYONE!



(I adapted this diagram from some youtube video but I can't remember where... I'll try to track that down and give credit!)

[Zil]

My suggestion. Don't need the 30 amp breaker between panels and controller. Better to have a heavy duty switch to turn off the panels if you need. Circuit protection is not needed there. Do need fuses on individual panels. I used 15 amp on my Renogy 100W. Prevent three panels feeding into one shorted panel. Why does the 4awg feed 6awg? I used a 100 amp fuse on 45 amp controller at the buss bar. Proper sized fuse for other circuits at the buss bar. Catastrophic fuse at the battery feeding the buss bar. In DC, fuses are better than breakers.

[Al and Missy]

I don't know about home run, can't you put the shunt in the line from the junction post to the battery negative? Don't know how significant that drain is, only a few amps for a few minutes, but it could build up error over time.

Al

[thiel]

Originally Posted by Al and Missy

I don't know about home run, can't you put the shunt in the line from the junction post to the battery negative? Don't know how significant that drain is, only a few amps for a few minutes, but it could build up error over time.

Al

My understanding is that the shunt needs to be protected from the elements, so it has to go inside the trailer...

[CoorsLite]

thiel - you & I just discussed this privately - this is for others here that might have the same question.

I have yet to find a trailer jack negative ground wire that I could disconnect or extend on my 2018 FC25 FB. I believe the jack is grounded via the frame of the trailer itself. So, I made sure I have only ONE (new, heavy) negative lead from my battery box to the Battery side of the shunt (which is installed inside). I have two heavy negative leads on the "load" side of the shunt, one to the distribution box, the other to the inverter. The Distribution box, Inverter etc. are grounded to the frame. This means the frame is essentially connected to the "Load" side of the shunt in my config. Lastly I ran a 10AWG wire from the external solar connector ground to the "load" side of the shunt.

My BMV seems to be working (and measuring) things fine.

[gklott]

I did a quick review. Several items to consider:

1. Where is your PV circuit ground-fault protection device (GFPD)? NEC Article 690.5 specifies the ground-fault protection requirements for grounded dc photovoltaic arrays. NEC 690.35(C) specifies ground fault protection for all ungrounded PV systems. The specified purpose of a ground-fault protection device (GFPD) as part of a PV power system is to reduce the risk of fire associated with a ground fault.

I put the GFPD directly in front of the charge controller - MorningStar GFPD-150V joined to the MorningStar TS-MPPT-60M.

2. String fuses. NEC article 690.9 outlines the over current protection requirements for photovoltaic source circuits. You must have a fuse in each string. I used an Eaton (Crouse-Hinds) CCBF06 combiner, which places 15A Bussman fuse in each leg. Another example is a Midnite Solar MNPV6HV 4X Disconnect/Combiner Box.

3. DC disconnect. NEC Section 690.13 outlines the requirements for disconnecting a PV system's DC circuit conductors. This disconnect should be readily accessible from the trailer's exterior. I placed a two-pole Blue Sea 6010 switch just inside the refrigerator access door. This disconnect would be in your diagram where the 30-amp breaker is. You must disconnect both legs if ungrounded at that point. I then placed the NEC required labeling just outside on the left side of the frig access door. - "SOLAR PV DC DISCONNECT INSIDE".

4. Over current protection device (OCPD - breaker or fuse) in + side out Victron to bus bar, unless Victron has one built in.

5. OCPD (one or more) in + lead from bus bar to 12 DC loads (inverter, converter, etc.) since bus bar has two current sources.

6. OCPD in + lead from batteries to tongue jack.

7. Where is your break away switch, brake service coming off the battery? This requires a Type II breaker. I used a Bussmann CB1921-20 Silver-Colored Type II Maxi Breaker.

8. Wire sizing. The maximum combined 12V DC load current (6AWG) should not exceed 75 amps, provided you used 90C, 6 AWG wiring. You should be using 105C rated stranded wiring.

You have a 30A breaker from the battery to the bus bar. Is that the maximum current your total 12VDC loads require?

What size inverter do you have? Mine is 1000W, and requires larger wiring.

9. PV warning labels. There are several warning labels you should place around the trailer. In addition to the solar disconnect exterior label above, there are several required labels, such as:
- combiner box warning
- PV source circuit warning
- 690.53 DC warning, listing rated MPP V and I, VOC, Isc, etc.
- Dual power supply warning, placed near your entrance door
I got mine from pvlabels.com in the 2017 NEC label set.

73/gus

[thiel]

Originally Posted by gklott

I did a quick review. Several items to consider:

1. Where is your PV circuit ground-fault protection device (GFPD)? NEC Article 690.5 specifies the ground-fault protection requirements for grounded dc photovoltaic arrays. NEC 690.35(C) specifies ground fault protection for all ungrounded PV systems. The specified purpose of a ground-fault protection device (GFPD) as part of a PV power system is to reduce the risk of fire associated with a ground fault.

I put the GFPD directly in front of the charge controller - MorningStar GFPD-150V joined to the MorningStar TS-MPPT-60M.

2. String fuses. NEC article 690.9 outlines the over current protection requirements for photovoltaic source circuits. You must have a fuse in each string. I used an Eaton (Crouse-Hinds) CCBF06 combiner, which places 15A Bussman fuse in each leg. Another example is a Midnite Solar MNPV6HV 4X Disconnect/Combiner Box.

3. DC disconnect. NEC Section 690.13 outlines the requirements for disconnecting a PV system's DC circuit conductors. This disconnect should be readily accessible from the trailer's exterior. I placed a two-pole Blue Sea 6010 switch just inside the refrigerator access door. This disconnect would be in your diagram where the 30-amp breaker is. You must disconnect both legs if ungrounded at that point. I then placed the NEC required labeling just outside on the left side of the frig access door. - "SOLAR PV DC DISCONNECT INSIDE".

4. Over current protection device (OCPD - breaker or fuse) in + side out Victron to bus bar, unless Victron has one built in.

5. OCPD (one or more) in + lead from bus bar to 12 DC loads (inverter, converter, etc.) since bus bar has two current sources.

6. OCPD in + lead from batteries to tongue jack.

7. Where is your break away switch, brake service coming off the battery? This requires a Type II breaker. I used a Bussmann CB1921-20 Silver-Colored Type II Maxi Breaker.

8. Wire sizing. The maximum combined 12V DC load current (6AWG) should not exceed 75 amps, provided you used 90C, 6 AWG wiring. You should be using 105C rated stranded wiring.

You have a 30A breaker from the battery to the bus bar. Is that the maximum current your total 12VDC loads require?

What size inverter do you have? Mine is 1000W, and requires larger wiring.

9. PV warning labels. There are several warning labels you should place around the trailer. In addition to the solar disconnect exterior label above, there are several required labels, such as:
- combiner box warning
- PV source circuit warning
- 690.53 DC warning, listing rated MPP V and I, VOC, Isc, etc.
- Dual power supply warning, placed near your entrance door
I got mine from pvlabels.com in the 2017 NEC label set.

73/gus

Wow... thanks for all this detail. I'm not sure I understand most of it... and although I assume it's both thorough and correct, there's a TON on here that I haven't seen anywhere in my research... and quite a few items that doesn't seem to appear in the "complete" package systems I see advertised from reputable dealers online.

Is it possible that some of these standards are for residential and not RV installs?

In terms of specifics:

1 -- I am going to skip this. Will it explode?

2 -- I have assumed these are built into the panels, but if not, I can add them.

3 -- Adding the blue sea switch in an outside compartment that kills off BOTH lines between panels and charge controller.

4 -- If by "overcurrent protection devices" you mean fuses or breakers, I think that the Victron has one built in, but if not, I will add one on that line.

5 -- Trailer already has a fuse on line to inverter. Sounds like I need to add one on line to converter? I would assume that would have already been covered somewhere in the factory setup?

6 -- There's a fuse in this line already from the factory.

7 -- I'm not sure what this means. Battery shut off switch?

8 -- Typo on the diagram. Going with 4 AWG wire to Inverter and main panel/converter in the trailer. (My inverter is 1000w)

9 -- Labels. I will take a look!

Yes, 30amp breakers should be sufficient for my system since I have 400 watts with less than 6 amps per panel


Thanks again... very helpful detail!

--Thiel

[glcmranger]

Check out your combiner box. Typically, there is already a 40 amp breaker inside the box...... there is if it's a ZAMP combiner box.

[gklott]

Originally Posted by thiel

Is it possible that some of these standards are for residential and not RV installs?

This is a common misunderstanding. In NFPA 70, National Electric Code, Articles 1-4 apply to all installations, like sizing wire and using OCPDs (breakers, fuses). Articles 5-7 are 'additional' requirements given specific situations. Article 551 is specific to RVs, and Article 690 is specific to solar installations. Article 690 describes when and where it applies to your 400W stand-alone solar system.

NFPA 1192, Standard on Recreational Vehicles, and ANSI/RVIA, Low Voltage Systems in Conversion and Recreational Vehicles, provide additional requirements and guidance.

For example, a common skipped detail in some "complete package systems" is the use of "listed" components throughout. Every item you install should have UL, ETI, or similar certification for the specific purpose. Have seen "home brew", unlisted solar combiner boxes, fuse boxes, connectors, etc. used in solar installations.

Originally Posted by thiel

1 -- I am going to skip this. Will it explode?

Explode? Don't know. Burn? Maybe. This GFPD is specific to prevent a fire. Because of the rough environment RV solar experiences, I strongly recommend adding GFPD. Midnite Solar and others sell these that should work with your system.

Originally Posted by thiel

2 -- I have assumed these are built into the panels, but if not, I can add them.

Few, if any, panels have fuses built in. You can use listed MC4 in-line fuse holders or a listed combiner box, like I used, with fuse holders for each string.

Originally Posted by thiel

3 -- Adding the blue sea switch in an outside compartment that kills off BOTH lines between panels and charge controller.

Excellent addition, with the label for first responders.

Originally Posted by thiel

4 -- If by "overcurrent protection devices" you mean fuses or breakers, I think that the Victron has one built in, but if not, I will add one on that line.

Yes, OCPDs are circuit breakers or fuses. I used Blue Sea Series 187 thermal circuit breakers. Some installations use Blue Sea ANL fuse blocks. Bussman (Cooper Industries) also makes a good series of listed fuse blocks and holders.

Originally Posted by thiel

5 -- Trailer already has a fuse on line to inverter. Sounds like I need to add one on line to converter? I would assume that would have already been covered somewhere in the factory setup?

Don't know about your factory setup, but there should be a "main" DC breaker before all the DC branch circuits. The breaker size is to protect the wiring you are using from the bus bar to the branch circuit panel.

Originally Posted by thiel

6 -- There's a fuse in this line already from the factory.

Covered.

Originally Posted by thiel

7 -- I'm not sure what this means. Battery shut off switch?

You have an emergency 'break-away' switch that you connect when you hitch up. It is the wire that activates the trailer brakes if the trailer separates from the tow vehicle. That switch should have wiring directly from your battery with a Type II breaker. It is likely there, but was not on your drawing.

Originally Posted by thiel

8 -- Typo on the diagram. Going with 4 AWG wire to Inverter and main panel/converter in the trailer. (My inverter is 1000w)

Depending on your wire type, 4AWG 105C rating is 165A, and if 90C wire, its 135A. Recommend confirming the wire temp rating. Xantrex, Magnum, Samlex, and other ~1000W inverters recommend a 150A circuit breaker or fuse.

Originally Posted by thiel

9 -- Labels. I will take a look!

Unfortunately, you see little of this in YouTube RV solar installations. It is really important for first responders and to help you sort thing out later on.

Originally Posted by thiel

Yes, 30amp breakers should be sufficient for my system since I have 400 watts with less than 6 amps per panel

To make sure we are talking about the same one, I am describing the "30 amp breaker" on the 4 AWG red wire shown between your battery and the positive bus bar.

Your diagram shows that bus bar connects to your inverter and all DC branch circuits. That means the 30 amp breaker must supply at least 100+A just to the inverter. As shown, that breaker is not just for supplying charging current to the batteries. May be a drawing error.

Originally Posted by thiel

Thanks again... very helpful detail!
--Thiel

Let me know if I can be of any additional help.

73/gus

[thiel]

Originally Posted by gklott

For example, a common skipped detail in some "complete package systems" is the use of "listed" components throughout. Every item you install should have UL, ETI, or similar certification for the specific purpose. Have seen "home brew", unlisted solar combiner boxes, fuse boxes, connectors, etc. used in solar installations.

Funny you should mention this because some of the components I bought from RV solar shops (big ones!) are not listed. Ugh.

Originally Posted by gklott

Explode? Don't know. Burn? Maybe. This GFPD is specific to prevent a fire. Because of the rough environment RV solar experiences, I strongly recommend adding GFPD. Midnite Solar and others sell these that should work with your system.

I'm gonna keep poking around at this. For a 400w (about 24amp) system, is there a particular one you might recommend?

Originally Posted by gklott

You can use listed MC4 in-line fuse holders or a listed combiner box, like I used, with fuse holders for each string.

So glad you mentioned this. I found MC4 fuses on Amazon for about $10 each. Too cheap and easy not to install!

Originally Posted by gklott

You have an emergency 'break-away' switch that you connect when you hitch up. It is the wire that activates the trailer brakes if the trailer separates from the tow vehicle. That switch should have wiring directly from your battery with a Type II breaker. It is likely there, but was not on your drawing.

Really great point. I don't know that I have seen the wire (maybe it splits off of the hot line from the jack?). I will look!

Originally Posted by gklott

Depending on your wire type, 4AWG 105C rating is 165A, and if 90C wire, its 135A. Recommend confirming the wire temp rating. Xantrex, Magnum, Samlex, and other ~1000W inverters recommend a 150A circuit breaker or fuse.

Sometimes even a blind squirrel gets a nut: my 6AWG wire is rated to 105C. Nice.

Originally Posted by gklott

Your diagram shows that bus bar connects to your inverter and all DC branch circuits. That means the 30 amp breaker must supply at least 100+A just to the inverter. As shown, that breaker is not just for supplying charging current to the batteries. May be a drawing error.

Ah... I'm seeing now that the Inverter should probably get it's own dedicated red cable, direct from the battery and flowing through a special breaker. I actually have the breaker already in my RV, so now I just need to run the cable. (I actually removed the dedicated inverter red line and used it as my main power line since it was thicker cable... so now I'll put a new one back in.) Black line from the inverter can go straight to the shunt, right? No need to pass through the (already packed) bus bar?


Thanks again for all this help! I'll try to get all this worked out and then redo my diagram to help other newbs!