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Help! Newcomer needs advice!

Oak_Sandalfoot

? Everybody Loves the Sunshine ?
Joined
Mar 16, 2022
Messages
44
Location
SWFL
Greetings solar community,

I need help setting up my first PV system in my Schoolbus RV conversion. It appears that I have a SCC that's too small for my specific panels, especially if they are arranged in series.
Here are my components:

*12v, 750w PV array (3 x 250 in series)
-Max VoC: 50.9 V (Sunpower)
*2500w PSWI (Reliable)
*100/50a MPPT SCC (Vic.)
*18a DC to DC charger (Vic. Orion)
*Lynx Power In busbar (modded to be a Fuse holder as well) (Vic.)
*412 ah lifepo4 battery bank (2 x 206ah in parallel) (SOK)
*DC and AC fuse boxes. (DC: 100a Blue Seas)
*Master disconnect, wired at positive output terminal of the Lynx
*Shunt (Renogy) for BM (Renogy) at negative output of Lynx
*Fuses:
-Inverter: 400a mega
-SCC: 60a mega
-Dc to DC charger: 60a (lynx), 50a terminal fuse (starter battery) (couldn't find 60a in this model)
-DC fuse box: 100a mega fuse
-Lynx positive output cable to battery: ???a ANL fuse with fuse holder

I've been working countless hours to learn all of this stuff on the internet from rock bottom/scratch with ZERO prior electrical experience. With the vast amount of information, seemingly infinite variations of design, conflicting viewpoints, my 'noobability', and the inability to discuss the issues face to face with a knowledgeable human, the whole process has been very challenging. I am proud of how far I've progressed in the past two months from the drooling idiot at the solar warehouse to someone who can actually read through a solar forum and understandstand the language and glean information; however I am not too proud to know that I still don't know sh*t and I need help!

When I dip my head into that huge barrel of questionable apples, these are a few that float to the surface:

1)Can the following devices (going into the Lynx Busbar/fuse block) all be wired with 6awg?
*Orion DC to DC 12v/18a
*50a scc
*DC fuse box (blue seas w/ blade fuses)
-100a, 150a max (I think)

2)Inverter to Lynx cable gauge? (Short run <2 feet)
*1/0, 2/0 or 4/0 awg?

3)Lynx to battery cable gauge?

*1/0, 2/0, or 4/0

4) I have some insulated 6 awg in two different types: one is like 50 strands or more, and the other is exactly 7 strands. Which is preferable to my application? Basically, coarse or fine strand cable? (I already learned that solid is not recommended for mobile applications)

5) Orion DC to DC 18a charger:
*Can it be wired to either the starter battery or alternator, or does it have to wire to both (I'm confused because none of the many, many install videos on 'the Tube' ever wire directly to the alternator.)
I'm assuming, based on extensive thread surfing, that connecting to the starter battery in effect connects to the alternator as well?

6) Is it advisable to put a dual pole DC breaker between the solar panels and the SCC? If yes, then what Amperage breaker)

7) Can the Inverter and SCC be grounded on the DC fuse box instead of the chassis? (Grounding to chasis is viable option if not)

8) What fuse (???a) between main positive of Lynx bus and battery bank? ANL, Mega?

9) Any recommendations or comments on my setup just based on the components listed?

Thank you in advance to everyone who contributes their time, money, and energy to make these sorts of 'far-flung' endeavors possible for a noob like myself.

Cheers,

Oak Sandalfoot

Follow my bus build!

IG: Dumpstarsdivingbus
 
Last edited:
No, its worse, it would take 3 SCCs. But it could be 75/15 SCCs.

And in parallel, you would need to fuse each panel before combining.
Thanks for highlighting this serious issue, kindred Sandal.

I just called the solar warehouse and, yes indeed, they sold me an undersized SCC because they did not have the correct size available. They are going to send me the next level up.

Much appreciated, sir!
 
Hold on...what about the 150/60 and the 150/70?
150V max input. Your panels have a Voc over 50. You could put 2 in series but cannot use your 3rd panel.

You could use 4 panels, 2S2P (just over 100V, 2x the Vmp).
What should I ask the solar consultant when she calls back regarding the 'swap out'?
How about some panels that will allow you to run 3 in series with a 150/50? Or for a 4th panel like you have and a 150/50.
 
Adding a 4th panel would be more feasible than switching them all out; although, I'm not keen on doing either if there's a better solution.
Does your suggestion imply a larger inverters as well?
 
My bad, that question was irrelevant to the topic. D'oh! Still wrapping my head around this.
Can you tell me why a 150/60 or 150/70 wouldn't work with the three 250 Sunpower panels in series?

Maybe I'm realizing like many others that I should have gone with 24v system..
But now I have all this 12v gear..
Ouch. ?
 
I'm giving this everything I've got, but right now I seem to be back at square one. Not sure what's what anymore. ?
 
No, its worse, it would take 3 SCCs. But it could be 75/15 SCCs.

And in parallel, you would need to fuse each panel before combining.
I currently have all three panels fused (15a or 30a, whatever they sold me with the panels) before they enter the solar cable gland.
 
I currently have all three panels fused (15a or 30a, whatever they sold me with the panels) before they enter the solar cable gland.
The cost of three 75/15s isn't unreasonable compared to the astronomical price of a large SCC. It appears that I would have to get different branch connectors (three 'doubles' instead of using two 'triple' branch connectors) correct. Also, would I have to add another positive and negative bus bar plus two more fuses and holders?

Thanks again for donating your time to help me!
 
150V max input. Your panels have a Voc over 50. You could put 2 in series but cannot use your 3rd panel.

You could use 4 panels, 2S2P (just over 100V, 2x the Vmp).

How about some panels that will allow you to run 3 in series with a 150/50? Or for a 4th panel like you have and a 150/50.
I thought that the 150 part of the 150/50 was the specific to 24v PV system?? That's where I'm confused about what separates 24v and 12v on the SCC.
 
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