Anything wrong with this design? (45ft class-A, Schneider, NewPowa, EG4LL)

[amt]

I'm thinking about going all-in on a solar system, since the federal tax credit applies to RVs that are considered second homes, and I'd like to be self powered in many cases when in the RV. Also, a big driver of this: when parked at home, I want the RV to supply power to my Telsa for charging, deleting that ~$60/month expense from my home's electric bill. Ideally, it would be nice to export all excess power to the house, and perhaps the Schneider can do that, but I would be happy with providing all or some of the electric need of the Tesla (Tesla plugged into RV).

Here's what I am considering:

inverter: Schneider XW Pro 6.8 kW, 48v
integration: Schneider insight home
mppt: Schneider Mppt 100 | 60
battery: 2 x EG4LLv2 ~10 kWh
solar: 32 x Newpowa 100w compact 12v solar panel
engine charging: 2 x 24->48VDC 1kW chargers, either MeanWell or DayGreen

This would be replacing a 24v based system with 2 x 4kW Trace inverters and 8 x 8D lead acid batteries (no existing solar). These inverters still work fine, and I would probably sell them to someone who wants to maintain that setup in their RV (very common amongst Prevost bus conversions).

The RV is a 2001 Featherlite Vantare, and includes a 17.5 kW generator, which I will want to maintain auto start/stop. Not yet sure if I need the Schneider start/stop module. My roof is mostly clear, having no rooftop AC. The solar layout would be three rows, left, middle, and right, with occasional breaks in the row of panels for things like vents, etc. Panels wiring would be 4S8P. Min temp VoC would be 89.7v, but it looks like I might be right at the max for Amps.

Having 240v split phase is important to me, as I intend to replace older AC systems with 240v mini-splits.

Technically, the new inverter has less constant kW, but in practice, I think it will be better, because it handles load imbalance much better, and as I move to mini-split heat pumps, the electrical demand will be lower. Worst case I stack another later, but I highly doubt that will be necessary.

I might consider 3 of the EG4LL instead of 2, just to be sure I have enough current for peak loads, and I'd like to be certain I can go overnight in the hottest of conditions (where I'd likely use the most energy) without starting the generator.

I do need to work out when the 24->48v chargers are enabled/disabled. These will provide charging from the coach's 24v engine system (4 lead acid, 2 alternators, >300 amp @24v). Not sure if I can just have these always enabled when the engine is running, and set a target voltage such that they never over-charge, or if I should do something more sophisicated and build some kind of controller that monitors battery current and kicks these on when needed. Most of the time, the solar PV is probably going to be sufficient, but there would be times it would not be.

Any feedback is greatly appreciated, thanks!

 

[BentleyJ]

Sounds like you've done your homework. You mentioned Generator autostart/stop and control of the 24V to 48V coach battery charging system. The Schneider inverter has 1 Aux relay with quite few built in trigger settings. The Gateway also has 1 programmable relay. I believe the inverter outputs 12V on the aux relay and the Gateway is a NO-Com-NC dry contact.

Couple of considerations. Is the gen autostart a 2 wire system and does it require "dry contacts"? Here is a relay board to convert the 12V output to dry contact if needed. https://www.pololu.com/product/2482/

As far as controlling the coach charging system it could probably be interlocked with the autostart so both could not be on at the same time. If you wanted to control them separately it may be possible. I'm not an expert on the Gateway or what triggers are available on the aux relay as I'm using the older ComBox.

 

[amt]

Thanks for the feedback. I'll have to check on the generator start, but I suspect it's triggered by 12v. I have generator start/stop buttons in multiple places in the coach which are probably 12v and interface to a dry contact already, but I'll have to confirm.

Good point on the engine charging vs shore power. I think have a proper series of relays should be able to make them mutually exclusive.

 

[400bird]

On your charge controller, I'm guessing it's the smaller 60/150?
It has a 150 volt max input. You could go higher than 4 in series to limit the number of strings. But I think you chose 4 in series so you could have 2 strings in each row of 8 panels.

On this charge controller you're over paneled, but within reason. It is limited to 60 amps on both the input and output.

Stepping up to the 80/600 doesn't seem like the right choice. But, the higher input voltage would allow you to put more panels in series and limit the number of runs down off the roof.

As far as covering you house loads, seems possible. It would take a watt-node in the house main service enterance to transmit the energy usage information.
I'm not sure what the loss of the watt node signal will do the Schneider when you leave the house...

 

[amt]

Yes, the 60/150. It does seem like I am on the limit, and I wish Schneider had a lot more options for MPPT. These panels will of course will never have optimal placement/angle for peak solar output, so maybe the 60/150 will be good enough. Worst case, maybe I take 4 panels off and use a completely different, non-communicating MPPT for those.

Still not quite sure if I am going to take the plunge, but I am certainly tempted. I have a few other projects I need to get done first (like a mini-split install in the RV), so I need to see how that goes to gauge both my speed to complete things and my interest.

 

[400bird]

I assume the top of the RV has some curve? So each row running down the length will have a slightly different angle? Depending on your parking situation, that will either help spread out the peak or lessen the output from one row. It's unlikely you'll ever see full output from the panels. And over panelling an MPPT is acceptable and normal.

 

[dougbert]

I have 4 (for 4 arrays) Conext MPPT 60/150, wired in 48v (24v modules, 2S4P mode) The 60/150 can handle 3400 watts in that mode

I love these CCs

 

[amt]

Yes, the RV does have some curve, and that's why I am going with 3 rows. I plan on wiring 4 consecutive panels in a given row, up to 3-4 "sets" in each row. I am a bit new to how solar panels get wired, so I am not sure it is optimal. What I would like to do is not prevent one set of in-series panels (which is getting good sun) to be degraded from another set of in-series panels (which are at a worse angle or obstructed by trees, etc).

If this works out well for the RV, I would also consider adding a second XW (and CC and batteries) to may garage with larger format panels and try to do grid load sharing, or at least create an essential loads panel for the XW to power, reducing even further the need from the grid.