Rate my setup please!

brygnar

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Hey all!

I'm doing a camper conversion on a Dodge Promaster 3500, and I've done a bit of reading and put together this wiring diagram.

(Sorry for the poor quality.)

The components are:

2x100W Renogy solar panels
30a Renogy Adventurer PWM Charge Controller
20a Renogy DC-DC Charger
1000w Renogy Pure Sine Inverter
100ah Renogy Lithium Battery
500a Renogy Battery Monitor


Not a Renogy fanboy or anything, they are just currently having a sale on a bunch of stuff.

I am more or less just sticking with manufacturer recommendations for the solar equipment regarding external fusing and wiring.

Additionally, I've purchased THESE busbars, and THIS Fuse Block.

The fuses I've purchased so far:
30a Circuit Breaker (between the car battery and the DC-DC Charger)
Renogy mc4 30a Fuse (between the solar panels and SCC)
E-Ting 10 Awg gauge inline fuse holders (one at 15a between SCC and battery - manufacturer recommended 18? But I couldn't find any at that amperage and downgraded - and one between the DC-DC Charger and battery at 25a - manufacturer recommendation)

I haven't ordered the 90a fuse between the inverter and the bus bar - I can't decide if I should do a bolt on fuse, or a 90a circuit breaker.

The wires I currently own are the 10 AWG that came with the solar panel kit, the 4 AWG connector wires that came with the inverter, and the 2 AWG wires from an inverter/battery setup that came with the van but is useless for what we need.

Things I'm missing - I can't decide if I know enough to size a battery disconnect correctly in the system, and I'm not sure exactly how to do that. Mostly I've been following a combination of manufacturer recommendations, vanlife website schematics, and about a half dozen hours of youtube videos.

Tell me what I've done wrong and what I can do better!

(Edited because I realized I had forgotten my battery monitor and shunt in the diagram)
 

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MisterSandals

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Renogy mc4 30a Fuse (between the solar panels and SCC)
Your panels will be about 6A so even if connected in parallel about 2x too big to do any good. Besides, you probably only need a switch (a 15A breaker is a common choice).
one at 15a between SCC and battery
But its a 30A charge controller so less than half as big as it should be.
I haven't ordered the 90a fuse between the inverter and the bus bar
1000W / 10V cutoff / .85 efficiency x 1.25 headroom = 147A
 

brygnar

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Excellent notes and very fast response, much appreciated!

I'd totally mixed up the manufacturer recommendations for which fuse goes where - got the one between the panel and the SCC and the one that goes between SCC and battery backwards.

Regarding the breaker switch for the panels - any product recommendations?

About the inverter - must have read the manual wrong (and forgotten the basics about fusing). I'll boost the size of my fuse.

Thanks again!
 

rmaddy

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You need a pair of MC4 Y connectors to connect your two solar panels in parallel. No need for the 30A solar panel fuse.

You have a 30A SCC so you need a 40A fuse, not a 15A fuse.

You should have a 150A main fuse right at the battery before the positive bus bar.

Your diagram shows bus bars connected to the battery. That's good. Then everything else should also go to the bus bars. The SCC should go to the bus bars. The DC-DC charger should go to the bus bars. The inverter and fuse box should go to the bus bars. Only the shunt should be connected between the battery and the negative bus bar.

The 90A inverter breaker should be at least 125A.

2AWG from the bus bars to the fuse box is likely way overkill. How many watts of DC loads will you have?
 

brygnar

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You need a pair of MC4 Y connectors to connect your two solar panels in parallel. No need for the 30A solar panel fuse.
I do actually have a pair of mc4 connectors, my diagram is just crappy. (I mocked it up quickly to post on here for critiques).

You have a 30A SCC so you need a 40A fuse, not a 15A fuse.
Another user pointed that out - I'd mixed up the manufacturer recommendations.
You should have a 150A main fuse right at the battery before the positive bus bar.
Is this a "things go really, terribly wrong" contingency? I'm definitely looking to make this as safe as possible.
Your diagram shows bus bars connected to the battery. That's good. Then everything else should also go to the bus bars. The SCC should go to the bus bars. The DC-DC charger should go to the bus bars. The inverter and fuse box should go to the bus bars. Only the shunt should be connected between the battery and the negative bus bar.
10-4!
The 90A inverter breaker should be at least 125A.
I can only assume I read the manufacturer recommendations wrong. I'll upgrade!
2AWG from the bus bars to the fuse box is likely way overkill. How many watts of DC loads will you have?
Not very many at all, and I know that 2 is monstrous - I just have some from the previous owner of the van who had even less of an idea of how to wire than me, but like me erred on the side of caution. Is there any downside to using cable that large?

Edited: I appreciate you taking the time to reply and give feedback!
 

rmaddy

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Is this a "things go really, terribly wrong" contingency? I'm definitely looking to make this as safe as possible.
If the battery ever shorts out it can send a massive amount of current. The main battery fuse is there to protect the rest of the system.

I can only assume I read the manufacturer recommendations wrong. I'll upgrade!
A 1000W inverter on a 12V system can pull 100A (even a bit more when the battery is really low). I sure hope the manufacturer didn't really say to use a 90A fuse.
Not very many at all, and I know that 2 is monstrous. Is there any downside to using cable that large?
Electrically there's no problem using 2AWG when you probably only need maybe 6AWG. Normally it would be a big waste of money but if you already have it then use it. It's just harder to work with and you need proper sized lugs with small holes for the fuse block terminals.
 

brygnar

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If the battery ever shorts out it can send a massive amount of current. The main battery fuse is there to protect the rest of the system.
That makes sense.
A 1000W inverter on a 12V system can pull 100A (even a bit more when the battery is really low). I sure hope the manufacturer didn't really say to use a 90A fuse.
I'm sure they didn't and I just misinterpreted it.
Electrically there's no problem using 2AWG when you probably only need maybe 6AWG. Normally it would be a big waste of money but if you already have it then use it. It's just harder to work with and you need proper sized lugs with small holes for the fuse block terminals.
That was my understanding, but I appreciate the confirmation.

This has been wildly helpful. Went from feeling like I was just leaping out into the dark to feeling the first glint of understanding.
 

brygnar

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Electrically there's no problem using 2AWG when you probably only need maybe 6AWG. Normally it would be a big waste of money but if you already have it then use it. It's just harder to work with and you need proper sized lugs with small holes for the fuse block terminals.
Would these guys work?
 

rmaddy

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Something like that. Just make sure you choose the correct sized holes for the terminals on your fuse block. I doubt the fuse block has 5/16" screws on it. The smallest I see on that link is 1/4" holes for 2AWG lugs. The fuse block might have #10 or #8 screws which will make it very hard to find 2AWG lugs with such small holes. I see that the 4AWG lugs come with the option for the smaller holes. So you may need to use 4AWG instead of 2AWG for the fuse block.
 

brygnar

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Something like that. Just make sure you choose the correct sized holes for the terminals on your fuse block. I doubt the fuse block has 5/16" screws on it. The smallest I see on that link is 1/4" holes for 2AWG lugs. The fuse block might have #10 or #8 screws which will make it very hard to find 2AWG lugs with such small holes. I see that the 4AWG lugs come with the option for the smaller holes. So you may need to use 4AWG instead of 2AWG for the fuse block.
Again, wildly helpful. Thank you!
 

FilterGuy

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Here is a single pole. Some break both + and - with double pole but that's a small array. I only break + wire.

Be careful with this type of polarized breakers. They are OK for disconnects if they are hooked up correctly, but it is not OK to use them for over-current protection on parallel strings (this is something I only learned recently)

Also, the NEC requires the disconnect break both the positive and negative branch.
 

MisterSandals

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Be careful with this type of polarized breakers. They are OK for disconnects if they are hooked up correctly, but it is not OK to use them for over-current protection on parallel strings (this is something I only learned recently)

Also, the NEC requires the disconnect break both the positive and negative branch.
This is good info!

What do you recommend for a 15A DP breaker for parallel strings?
 

FilterGuy

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This is good info!

What do you recommend for a 15A DP breaker for parallel strings?
Edited for correctness (I said disconnect but meant OCPD)
Any quality non-polarized DC switch or breaker will work for a string over-current protection device. I do not have a specific recommendation.

Background:
See this video about what happens when a polarized breaker is manually turned off while current is back-feeding:


For a disconnect, you can wire a polarized breaker such that the current will always be going the correct direction.

For string breakers, it is a different story. The over-current protection on parallel strings is there to protect from a situation where the *other* strings are dumping current into a shorted string. For a polarized breaker to accomplish this, it must be wired with the positive pole away from the string it is on. However, that means that in normal operation, the current is going 'backward' through the breaker.... and if you manually turn it off... you risk it catching fire.
 
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brygnar

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Any quality non-polarized DC switch or breaker will work for a disconnect. I do not have a specific recommendation.

Background:
See this video about what happens when a polarized breaker is manually turned off while current is back-feeding:


For a disconnect, you can wire a polarized breaker such that the current will always be going the correct direction.

For string breakers, it is a different story. The over-current protection on parallel strings is there to protect from a situation where the *other* strings are dumping current into a shorted string. For a polarized breaker to accomplish this, it must be wired with the positive pole away from the string it is on. However, that means that in normal operation, the current is going 'backward' through the breaker.... and if you manually turn it off... you risk it catching fire.
Other than the convenience factor, would there be any issue with using an inline fuse holder and just pulling the fuse if I need to work on it?
 

FilterGuy

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Other than the convenience factor, would there be any issue with using an inline fuse holder and just pulling the fuse if I need to work on it?
No there is no problem at all with that. In fact, I am starting to think that is the best way to go for PV string protection.

There are DIN Rail fuse mounts that work especially well for this purpose in combiner boxes. The fuse holder can be opened almost like a switch, and it disconnects the fuse without the fuse falling out.


1649615287192.png1649615325413.png
 
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Bud Martin

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So if you use DIN fuse holder as PV protection and also as disconnect, do you require to have one for + and one for - to meet NEC?
 

FilterGuy

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So if you use DIN fuse holder as PV protection and also as disconnect, do you require to have one for + and one for - to meet NEC?
I *think* the requirement is that both sides have to be disconnected at the same time. If so then the fuse holders I referenced would not meet code.

Again, a two pole breaker just before the SCC can be polarized as long as it is hooked up correctly and sized correctly. However, I see no way to safely use a polarized breaker for the string over-protection device.
 

Bud Martin

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I *think* the requirement is that both sides have to be disconnected at the same time. If so then the fuse holders I referenced would not meet code.

Again, a two pole breaker just before the SCC can be polarized as long as it is hooked up correctly and sized correctly. However, I see no way to safely use a polarized breaker for the string over-protection device.
I do not quite understand what you mean by 'no way to safely use a polarized breaker for the string over-protection device', sorry English is my second language.
I also see combiner box sold by WATT247 that has fuse holders for + and - and then feeding the ganged polarized circuit breaker, I wonder if that is OK.
 
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