Please critique my solar plan

[chriscowles]

1. Newpowa 180W 12V monocrystalline panels (Datasheet) in 2S2P array
2. EPEver Triron 4210N MPPT SCC (Manual)
3. SOK Battery 12V 100A LFP battery (Spec sheet) in 2P array
4. Renogy 2000W 12V PSW inverter (Datasheet)
5. Xantrex 15A inline transfer switch (Owner guide)
6. WFCO WF-8955 converter/charger (Manual)
   
   Plus cables, bus bars, fuses, switches and breakers as appropriate.

My plan is attached. I hope it's readable. I used a trial version of SmartDraw and have only 4 more days to use it. I can't generate a readable PDF because it's covered with watermarks.

720W of panels will lay flat on the roof and will be subject to shading. Wiring on the roof will be the 10AWG and MC4 connectors provided with the panels. I may need about 10' of extension. I'll get something ready-made with MC4 connectors, because the salvaged and repurposed roof gland has them, as well. From inside the roof to the SCC (about 10') I'll use 8AWG. They'll be paralleled with an MC4 branch connector. The route to the SCC will be direct, straight down the front closet.

6AWG welding cable will be used from the SCC to the positive bus bar. It's the largest allowed by the terminal. From the battery to bus and to the inverter will be 2AWG. The inverter will draw < 200A at the rated current and 370A for a brief surge. The wire size calculator says 2AWG is acceptable for 2% drop over 6 feet (round trip) and 370A will result in a 5% drop. Being very short term, is that okay?

I'm using the OEM WFCO 3-stage lead-acid charger and will rely on the solar system to charge the LFP batteries completely. I'm replacing the ~20' of OEM 8AWG conductor from the converter/charger to the battery with 4AWG. I will replace the single conductor/chassis ground with both positive and negative conductors. The chassis grounds will be improved with 4AWG, as well. That and some new and existing 12V loads will be on a separate positive bus, allowing disconnecting the trailer from the battery while leaving the solar system engaged. The Blue Sea switch I have allows the converse, as well.

A Xantrex 15A ATS will be plugged into the inverter. I'll run 14/3 NM-B from the power center. One leg will be from the 15A breaker for the microwave oven circuit. I'll connect the return leg to the wire I pulled out of the breaker to make way for the 14/3. The neutral will be common.

I'm wiring the Renogy remote switch in series with the relay com slave module on the SCC. That way either the switch or the relay will cut off the inverter. The remote switch and the battery monitor will all be in one place on the kitchen wall next to the refrigerator, along with the remote display of my Progressive Industries EMS.

All suggestions are appreciated.

Edit: uploaded cosmetically tweaked image. No material changes.

[mbutts]

I'm sorry that I can't offer help, but thanks a ton for this awesome and detailed post. I've been researching solar for several years because I don't really want to write a check for $10,000 for an installed system.



What I learned yesterday was that my battery isolation manager from Precision Circuits won't work with lithium since it's REALLY old (almost 4 years!). It seems like there's a ton of other stuff like this that would show up and I'll learn later "Well of course you can't flush the toilet and make coffee at the same time!"


That last sentence was meant as a joke and does not imply that you and anyone else's water pump, toilet, black tank, macerator, brand of RV TP, or use of coffee creamer will cause issues with your particular solar setup. I'm only illustrating that there seems to be a lot of undocumented gotchas in designing a solar system for an RV.

[chriscowles]

Thanks for your comments. I'm glad my diagram was a help and hope it does not result in harm due to our mutual naiveté.

I've revised the plan some. For one, I'm going to use 2/0 AWG from battery to inverter rather than 2 AWG.

Also, for some reason it wasn’t clicking that the microwave oven and convenience outlets would (of course) be on separate circuits, and that my 15A ATS was good for only one of them. There’s no way for me to arrange for two circuits to be on the same small 15A ATS, and I can’t run the main through it because 30A shore power would burn it out.

I’m returning the Xantrex ATS in favor of a (cough cough) WFCO 30A ATS. I have to assume it works at least as well as the power center. Amazon user reviews (validated by ReviewMeta) support that theory.

An advantage is that it’s designed to fit on the back of the WFCO 8955 power center, so I don’t have to find space. It also frees space in the compartment where I’ll mount the SCC and inverter.

Since the ATS will be mounted on the power center rather than next to the inverter, I'm using 10/2 NM-B between then, rather than 14/3. It's overkill for 15A but allows future upgrade of the inverter, should I ever be silly enough to do that.

[chriscowles]

Originally Posted by mbutts

... What I learned yesterday was that my battery isolation manager from Precision Circuits won't work with lithium since it's REALLY old (almost 4 years!). ...

Not having a motor home I'm unfamiliar with some of the electrical devices, such as a battery isolation manager. That said, the OEM WFCO converter/charger in my travel trailer isn't "compatible" with a lithium battery, either.

In my case that's okay because I'm not dependent on the converter for fully charging the lithium batteries. The solar charge controller will handle the fine details. If I were only buying LFP batteries and not installing a decent solar system, I'd have to replace at least the converter/charger section of the power center. But, since I am installing a solar system, I can ignore that weakness.

I also have a Noco Genius stand-alone charger that is lithium compatible, should the occasion arise that we don't have sun for a few days and I have to charge the batteries with my generator. Even that may be overkill but I (think I) need it for an initial full charge of the new batteries before connecting them in parallel for the first time.

Whether any of the above is relevant to your BIM not supporting lithium, I don't know. But don't draw conclusions without doing further research. There are many sources online, including helpful people here.