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Hello All First Post Solar Design

Glenn.Hurley

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Joined
Nov 16, 2021
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11
Hello, First Post
I have been lurking on this board and watching Will's Vids for 6 months.
I have a lot of electrical wiring experience, dad was an electrician.
There is so much great knowledge here but solar it can be a little overwhelming.

So I have studied as much as I could made some decisions to wade into the Solar world for my Travel Trailer.
I am about 25% of the year on the road but planning on upping that tp 75% and exploring the west next year.
I started with 2 lead acids and a 200 Watt Renogy/PWM suitcase this year. It is Ok but if I am going to boondock I need AC power.

So I designed a system based on adding 400Watts and an MPPT and upgrading to 2 Battle borns with a 2200W inverter for growth.
I just need occasional 1500 Watt loads for short periods. I have a 3500 watt geny to run my AC if I need it.
I am little uncertain of the 1/0 wire is overkill and if I have maybe missed a fuse or 2. o_Oo_Oo_O
Any feedback from the Gurus here would be appreciated.

200Watt Renogy Suitcase 30Amp PWM
400Watt Rich solar kit 40 AMP MPPT
Go Power Transfer Switch
Giandel 2200W Inverter (Smoking Deal onBlack Friday)
(2)Battle Born 100AH (Smoking deal on Cyber Monday)

I will post as I build and hpe not to release any magic smoke.
 

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Frankly, just throw the PWM controller away. Wire all three panels in series to get ~61V and feed that into the MPPT controller only. It has a 100V limit. You'll gain more power that way. Wired in parallel the way you've drawn it, you'll lose almost half the amps coming off the PWM string. Make sure though that you first only connect the controller to the battery, and wait till it boots up. After it's online, then attach the solar string.

On paper, it looks as if the amperage of three panels is going to overload the controller, but that's not what happens in the real-world. Assume that your panels when perfectly aligned with the sun are going to put out about 85% of their rated output. So, what you will actually see is (600W/13Vcharging) X 85% = 39A. If the panels are laying flat then only (600W/13Vcharging) X 75% = 35A.
 
The AC breaker panel should be connected to the AC-out of the inverter, not to the transfer switch.

You have a 2200W inverter on a 12V system. 2200W / 12V / 0.85 = 215A. For that I would use 2/0. The 1/0 is actually a bit too small. Then you need a 250-275A breaker.

Consider a fuse between the positive bus bar and the inverter.

It's common to have a disconnect breaker between the solar panels and the charge controller. The charge controller should also have its own fuse (50A) to the bus bar.

The 40A output of the charge controller should be wired with 8AWG, not 10AWG.
 
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Ooops forgot the 50Amp CB on the MPPT to the Battery, Thanks.
I like the serial panel idea, I could do that with the 2 on the roof, but the third is ground deployed so I would need some kind of switch when it was not in use. Maybe I can serial the 2 roof panels and plug the PWM for the ground panel in when I am using it. If I need more panels later I can add them in Series/parallel.

I thought the 250AMP fuse from the Battery to the Buss Bar would protect the wire to the inverter?
The inverter feeding the panel confuses me, how would the Transfer Switch switch between the inverter and the Show Power feeding the AC Panel.
 
Fuses/breakers protect the wire, not the devices. The 250A fuse is protecting the wire between the battery and bus bar. The wire to the inverter needs a fuse. The wire to the SCC needs a fuse, etc.

Please disregard my previous comment about the AC panel, transfer switch, and inverter. I have an inverter/charger with built-in transfer switch so I didn't deal with all of the separate components and I was misthinking it when I made that previous comment.
 
Ok so need another fuse after the buss, cool.
No worries, Inverters come in so many flavors, with TS, solar CC, I should have been more specific.
I did contact Giandel last week and they said the wires are pure copper and sized for their inverters.
They are 35mm2 which as far as I can tell is 2 AWG.
They said use them and call if there are issues, YIKES!
I think I will use the larger cables.
 
I am planning to put a disconnect on the negative side of the battery.
Which would typically go first the disconnect or the shunt?
 
Most people put the battery disconnect switch on the positive wire. It would go between the battery fuse and the positive bus bar.

If you plan to keep the battery breaker then you can simply use the breaker as your disconnect. Just be sure there is minimal load before disconnecting.
 
Just to jump on this thread and ask a couple of questions, I’m a little confused with some of the observations and suggestions.
First, I have a very similar setup. You need to be careful with installing a cut-off switch between the battery and the bus bar. If your switch is off, you won’t be supplying power to your brakes and that’s a big no no.
Second, I don’t understand why it is recommended to install both a fuse between the positive battery lead and the bus bar and another one between the bus bar and the inverter. Since the power load is coming from the battery, one would be enough in my opinion as long as the bus bar is rated to handle the voltage and amps. It’s not really any different then having one continuous wire running from the battery to the inverter. Both wires are protected from that single fuse. Also, having more splices in your wire will induce more voltage drop which could be detrimental to your system and cause even more heat issues if one of the connections is loose. Please forgive me if I’m wrong.
Another point, it’s a 12V system right? I would think a breaker would be fine for a 12V system. I’d be more concerned about drawing too many amps out of that battery with a 2000 watt inverter.
 
You need to be careful with installing a cut-off switch between the battery and the bus bar. If your switch is off, you won’t be supplying power to your brakes and that’s a big no no.
The brakes are powered from the tow vehicle through the 7-pin, at least while towing. On my trailer there is a separate battery on the tongue that is only used by the brakes in a trailer runaway situation. The electrical system I added to the trailer is completely independent of that battery and the brakes.

I don’t understand why it is recommended to install both a fuse between the positive battery lead and the bus bar and another one between the bus bar and the inverter. Since the power load is coming from the battery, one would be enough in my opinion as long as the bus bar is rated to handle the voltage and amps. It’s not really any different then having one continuous wire running from the battery to the inverter. Both wires are protected from that single fuse.
There are a lot more components than just the battery and inverter. Each thing connected to the bus bar should be fused to protect that set of wires.
 
The brakes are powered from the tow vehicle through the 7-pin, at least while towing. On my trailer there is a separate battery on the tongue that is only used by the brakes in a trailer runaway situation. The electrical system I added to the trailer is completely independent of that battery and the brakes.


There are a lot more components than just the battery and inverter. Each thing connected to the bus bar should be fused to protect that set of wires.
That is smart to keep the brakes separate from what you added. I agree.

I also agree that everything that is connected to that busbar should also be fused based on its current needs. But I was specifically talking about the inverter. Again, that entire current from the battery to the Inverter is being protected by your fuse. I understand why you wouldn’t want a single fuse between the inverter to the bus bar with other things being connected to the bus bar(and not having one between the battery and bus bar) but two fuses protecting the same circuit? I’m pretty sure that the SCC isn’t going to have much of an effect in melting that line between the bus bar and the inverter considering the wire size of that line as well as the fact that there is already a separate fuse for the SCC.

If the wire is rated for it, only one fuse is really needed. We don’t put fuses between every single strand of wire. We typically only need one as close to the battery as possible protecting the devices/wire downstream.
And if I’m wrong, I apologize. But as an example, That’s like saying I need a fuze between my SCC and my shut-off as well as another fuze between the Shut-off and the bus bar to protect each wire(do I need another one between the bus bar and battery?). It’s not needed. Only a single fuze is needed on that line. A lot of people run a single 15Amp or 30Amp fuse between their PV panels and their SCC to protect the entire wire even if they also have another shut-off between them or additional MC4 connectors to extend the line. They don’t put yet another inline fuze after every connection.
 
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If there is a short between the bus bar and something else in the RV other than the inverter, which fuse will break? Personally, I would want the one that would terminate all connections coming from the battery to trip for obvious safety reasons. And if there is a short between the inverter and something else in the RV, again, I would want everything to be terminated as close to the battery as possible and not just the inverter terminated. I certainly wouldn’t want that bus bar to stay hot with power with an issue like that going on.

Remember, the current is going to take the path of least resistance and that first fuse will blow protecting everything else downstream.
 
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I will tie the brakes and tongue jack in on the hot side of the disconnect so no worries.
What I am struggling with is the 7 pin 12 volt power.
If 7 pin 12 volt aux powers the break away controller and brake away controller gets power from LI Battery only when breakaway is engaged.
Then the 12 volt pin on the trailer side will only see 12 volts when the breakaway is engaged which means it is probably dangling.

I guess my questions are I want confirmation that 12 volts from 7 pin will never go to battery under normal conditions
I will not be charging LI from my tow vehicle which would be good IMO as I have no DC2DC charger
 
It really depends on the vehicle and how it is set up from the manufacturer. My 7 way only sends about 13.4V when it’s on and even then I’m lucky to get an amp or two at most if my LiFePo4 is lower than that voltage. However, if my truck is off, the voltage goes the other way and my LiFePo4 tries to charge the trucks battery. So I just disconnect when I’m stationary. I have just pulled the fuse in the truck to disable the 7 way altogether but I’ve done some 12 hour trips and a 2 amp trickle is better then none at all to run the fan in the fridge.
My suggestion is to just pull the fuse. It does not disable the brake. It only disables aux power charging the battery of the tow vehicle. I see more of an issue with the charge from the LI going to the truck batteries then than the other way around.
 
Thanks , it the 12 volt will not hurt the battery, sounds like it will not do much, I guess I could install a diode to block the backflow.
Pulling fuse sounds way easier LOL
 
Fuses and breakers are for protecting the wire not the equipment, it should :devilish: be designed to take care of itself.
 
Finally finished this project, well the first phase, see photos.
I have the inverter, transfer switch, monitor and wiring to roof and a frame done.
I am driving this with a 200 Watt panel and PWM attached at the a frame and getting 60 amps a day of power (mostly sunny days).
Really cool!

Next I will start the roof panels project, I am doing some testing at different loads to decide what panels to use.
Maybe 3 200 watt 12 volt into an EPever Tracer bn 40AMP.
Not sure if I can use 24 volt panels on the roof into the Tracer charging 2 12 volt Battle Borns in Parallel to lower the amps on the solar size over my 10 AWG wire, Would like to be a little over paneled for roof and clouds.

Thanks for the generous support and comments that helped me do my fist Solar project
 

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