Starting to get really frustrated with an RV solar setup.

Re: Starting to get really frustrated with an RV solar setup.

In fact, as I look things over, I can't even see why I need the combiner box at all, I should just be able to use three of the five breaker slots in the Mini DC Disconnect for that, out to the CC, back in to the Mini DC break, off to my batteries to my inverter via the 175a breaker and that would leave me with two breakers for all of my 24v loads. That seems like going at this with Occam's razor, trimming all of the fat and leaving me with a clean, simple install.

Re: Starting to get really frustrated with an RV solar setup.

I'm making some progress! I scored 8 brand new US made Solar World 230w panels today at $0.69 per watt, it took some doing to get that good of a deal locally and on less than a pallet but I'm excited to have that off my list!

What I'm learning is the following:

1) The only places a compromise free solar system exists is in Bigfoot's house.

2) You really need to make some educated choices and go into this knowing your goals of the end system and what it will take to get you there. Asking people creates confusion as they're all willing to do different compromises.

mike95490 wrote: »

What sort of wind speeds to you expect the rooftop panels to be able to survive? Headwinds, going over a bridge seam in the road, can give a pretty nasty shock to a sheet of glass solar panel.

If you can rig up your PV array to just 2 strings, you can drop a combiner channel, to just 2 breakers, if your Classic will handle the voltage.

2, 24V agm strings in parallel. That's going to require a lot of care to do it right, without cooking a battery early. You could put all 4 of them in SERIES, build up a 48V system and not worry about parallel batteries. have you already bought a 24v inverter ? would 48v break anything (24v fridge you already have ?)

This is two examples of compromise for me, I'm in an RV, I can't always account for power poles, trees and so on as they will change every single day. As such, series strings are a HUGE liability and running to versus three strings could put me in situations often where I'm without 1/2 my power versus 1/3 of it.

The 24v versus the 48v is another, I can't run a 48v bank with my solar panels configured as 3 banks of 2 so I would have to run them 2 banks of 3 and that creates the aforementioned issue. As I mentioned above, these are experimental batteries, if I can get 12-24 months out of them I would be more than happy. Parallel can't always be avoided in the real world and this is one situation where this is my only option, running a 48v system in an RV with under 2kw of panels offers no major gains for all of the troubles in creates.

Thank you for the input, this would all really apply in a stationary application for sure and I would do it this exact way.

zoneblue wrote: »

Fully agreed on off grid being 10 times more complicated!

Unyallis idea is pretty cost effective. Your idea of putting the string breakers in the mndc, that will work fine too. The one occassional hassle ive had is having to be careful around the pv hot wires when working on the disco. But if you do it right the first time, you shouldnt have to work on it again...i suppose. Learn from my mistakes.

The great thing about the mndc is it herds you into good components and a safe setup. Im not big on battery switches and stuff bolted all over the show. Most the dangerous stuff is then inside the mndc. Good conduit from there to the bank, and something to protect the bank itself from shorts, and you have 99% of the safety bases covered.

No worries on the documentation. Its kind of habitual.

Just remember that the battery is the biggest hazzard. The deliverable current dwarfs anything the grid will ever do. Second to that is the PV which while inherently current limited, its higher voltage DC can produce and sustain plasma arcs like nothing youve ever seen, which is your second main fire hazzard. PV arcs start at about 30V+, and get worse as the string voltage climbs. Your strings are 60V-80V. On a moving vehicle, abrasion, and whatnot to consider. Lots of flexible conduit, good grades of cable, well tied down cables, particular care on the roofing penetrations / anywhere else cables pass though sharp bulkheads etc.

Thank you for mentioning some of this. I have arc welded with three 12v batteries, I used to actually keep some rod with me on trails as you never know when an axle may need welding in the field. I guess the question for me is just how much risk is there of shock on the DC side in a system like this? I can touch live 24v wire no issue right? What about 48v? Or as you mentioned the 60v-80v going on to the cc?

In terms of a short, I'm in an aluminum box, seriously, 2,600 pounds of it, even the floors! So I will really take what you're saying to heart to make sure I'm on the extreme safe end of things. I'm making a box for the batteries to go under the seats, I will be fabricating this and may see if I can even find something plastic to put inside of that box to be on the really cautious side of safe.


PS To make matters even worse, I'm adding a 7th panel to a cheap mppt controller for a small 12v battery bank to run my 12v items, give me some additional experience with a system that isn't my main system and well, because I already have the solar panel and batteries. This will be a fun system though, low use, something I don't have much invested in, won't use with an inverter and keeps me from having to use a step down on the main system for the 12v things.

Thank you all!! I'm feeling a lot better about this build now, excited even!