Creating a portable RV solar system

[sunny butts]

Hoping this will be of use to others. I have not settled on my ideal RV; but going solar with 6 months, 400ah bank, 12v, haven't sized panels yet, NH, shady, going to need something suitcase-ish even if it's homemade. To the question. Looking for examples or advice on how to construct a system where I can relatively easily move it from one RV to the next. Batteries will be either in a insulated heated cooler in the pass-through as I want to explore winter glamping, or under the bed, solar charger, inverter, BMS (internal to batteries?). Care about safety (will use the fire suppression sticks); and a 1/2 day remove and reinstall. Many thanks.

 

[Dzl]

I don't understand why you want a portable system for an RV, seems like it introduces added design complexity and limitations for potentially little gain. On the other hand semi-modular/removable may not be too difficult to design. Can you briefly explain your goal/constraints that are leading you in this direction? In what situation would you need to move an entire core electrical system from one RV to another frequently enough to want to make it portable?

Whatever your reasons, its a fun sounding thought experiment so I'm happy to play along, and suspect others will be to. But explaining the 'why' question will help guide the answers you receive and pre-empt more comments like mine.

 

[pollenface]

I built a plug in system once that I could move from my shed to my camper, it consisted of 2x 50ah lifepo4 batteries in series for 24v and a 3kw inverter, basically strapped everything to a rectangular piece of plywood that would fit on a shelf or under a seat/bed. The shed and the camper had their own sets of solar panels.

In hind sight, the 3kw inverter was overkill because my batteries only had a 100a discharge current rating and I would occasionally overload them the BMS's would disconnect and things wouldn't be much fun for a while.

 

[sunny butts]

I don't understand why you want a portable system for an RV, seems like it introduces added design complexity and limitations for potentially little gain. On the other hand semi-modular/removable may not be too difficult to design. Can you briefly explain your goal/constraints that are leading you in this direction? In what situation would you need to move an entire core electrical system from one RV to another frequently enough to want to make it portable?

Whatever your reasons, its a fun sounding thought experiment so I'm happy to play along, and suspect others will be to. But explaining the 'why' question will help guide the answers you receive and pre-empt more comments like mine.

The solar system is an investment if you do it right, right? And I see myself going through 3-6 RVs over the next 2 years; and I don't see getting my ROI from future buyers as solar is still a low percentage desired option in the NE. It's like the old real estate rule, a pool, causes a large percentage of buyers to walk away. So, I want to be able to move the solar system from my current RV to my new. Heck, I'm moving my tankless water system and suspension from my old to new, along with my helper springs on my F150. With 4 kids in or recently graduated from college, every $500 helps.

 

[Dzl]

As a starting point, a couple rough numbers

Two of the most efficient, most $$$ PV panels I'm aware of come out to about:
220 watts per square meter of solar
51 kilograms per kilowatt of solar

The one of the most energy dense cells I'm aware of come out to about:
5.65 kilograms per kilowatt-hour of capacity
2.65 liters per kilowatt-hour of capacity

If you want 400AH @ 12.8V that is ~5kWh and roughly 28kg at an absolute minimum
1200W of solar would require a bit under 6 square meters of space at an absolute minimum and about 60kg

 

[Dzl]

The solar system is an investment if you do it right, right?

Sure, or at least it can be. I'm not sure how the economics of it work out with an RV/mobile build, particularly trying to factor in moving it between RV's. My gut instinct is the juice wouldn't be worth the squeeze to me, but I'm interested in thinking it through regardless.

And I see myself going through 3-6 RVs over the next 2 years;

? wow!

So normally the first thing people will tell you to do is an energy audit. Its really hard to properly size and design a system without knowing what your average daily consumption is, peak consumption, etc. I'm not sure how you arrived at your 400Ah number, do you have a ballpark idea how much energy you will consume?

If this is just more of the 'thought experiment' stage, we could just make some assumptions as placeholder values and go from there.

 

[Zwy]

Hoping this will be of use to others. I have not settled on my ideal RV; but going solar with 6 months, 400ah bank, 12v, haven't sized panels yet, NH, shady, going to need something suitcase-ish even if it's homemade. To the question. Looking for examples or advice on how to construct a system where I can relatively easily move it from one RV to the next. Batteries will be either in a insulated heated cooler in the pass-through as I want to explore winter glamping, or under the bed, solar charger, inverter, BMS (internal to batteries?). Care about safety (will use the fire suppression sticks); and a 1/2 day remove and reinstall. Many thanks.

You should maybe look at the portable power stations like Bluetti and other brands. Something like this 3000w inverter https://www.bluettipower.com/products/ac300-b300 note that it comes with an extra battery module or the 2200w inverter https://www.bluettipower.com/products/ac200max-power-station depending on inverter size you would need. It sure would take 1/2 to move it. You can add more B300 battery modules if you want more capacity.

All you need then are solar panels.

BTW, Bluetti is running a Christmas sale https://www.bluettipower.com/pages/christmas-2021

 

[jberger]

Have you ever owned and lived in an RV before?
The idea that you might go through 3-6 RV's in 2 years is hard to fathom. It normally takes that long to get one RV setup exactly like you want it as each trip/visit creates another item on the to do list. And depending on what you are trying to sell, it can take months to unload one, even in a hot market as everyone seems to want something different.

If you plan to just flip them, I kinda understand but in that case you'd be better off building an RV Shed with solar on top, and just putting the TV underneath while you have it.
The transaction costs on the 3-6 RV's will be a lot more than you might think, plus you have to go through the tag office, insurance changes, etc. It all adds up and takes more time and money than you think.
I've run the numbers, and the transaction costs, time and customizations make flipping them often just too expensive.

IF you standardized on a 12V system, you could conceivably move the ATS, Inverter and Batteries to a new system. But given the price of panels, I'd just mount them permanently and consider it part of the unit. Otherwise you'd need to play rooftop jenga for every different model as the roof obstructions are going to be different.

 

[Rednecktek]

So noodle thought, on those rackmount batteries is there enough space to mount the SCC, inverter, fuses, etc and glue/screw/duct tape it to the battery itself? They're what, 19x24 or so? Seems like that would be a complete build that you just have to plug in (outlet for shore power connector?) and clip in the panels?

 

[Dzl]

Before going too far down this thought-path, I think you need to assess the feasibility (not of it being possible, but it being practical/convenient enough for you to actually want to do it 3-6 times).

You mention wanting a "suitcase" like setup of some kind. You also mention 5kWh capacity (400Ah @ 12V). I think you might be imagining a vastly smaller system in your mind, than would be practical for the size system in reality. Or maybe not. Its hard to know without consumption numbers.

But 5kWh is going to be [at the absolute minimum] over 60lbs [for the cells alone]--heavy but not that bad on its own. But then consider a reasonable amount of PV to recharge a 5kWh battery (assuming solar is your main and only reliable charge source and that you need/want the ability to have a fighting chance of recharging from empty to full in a day or two of good sun). a couple 50W or 100W panels made into a solar suitcase would not cut it, not even close. You could potentially make 3-8 of these suitcases though, for 600W to 1600W of PV.

Maybe using larger panels would be more convenient. 3 x 'solar suitcases' using 200W panels could get you 1200W for roughly 230lbs in panels and pack down to a minimum of roughly 5ft x 2ft x 0.75ft not counting whatever sort of structure you add.

If you install the batteries and solar charge controller to an external storage compartment, you could avoid any permanent wiring/holes in the roof/etc with regards to solar. How you hook into the RV's existing AC and DC system seems a bit more difficult to do in a way that easily portable from RV to RV unless you maybe just install simple and redundant components (a small inverter with a couple 3 prong plugs, not hardwired to anything for instance).

 

[rmaddy]

But 5kWh is going to be upwards of 60lbs

4 drop-in 12V 100Ah LiFePO4 batteries will be more like 120lbs. 2 drop-in 12V 200Ah batteries might be closer to 90lbs. I suppose a DIY battery can be a little lighter depending on the case but I think 60lbs is really optimistic.

 

[Dzl]

4 drop-in 12V 100Ah LiFePO4 batteries will be more like 120lbs. 2 drop-in 12V 200Ah batteries might be closer to 90lbs. I suppose a DIY battery can be a little lighter depending on the case but I think 60lbs is really optimistic.

You are right, 60lb is literally the most optimistic (and then some). Unrealistic really, just a ballpark of the absolute minimum weight for 5kWh. In my earlier comment I was clear about my numbers being the absolute minimums (for the cells alone), but dropped/forgot the disclaimer (unintentionally) in my followup post. I should go back and clarify.

Because there are so few details and specifics in the OP, I'm sorta treating this as a thought experiment at this point, and musing about some vague minimums, extrapolated from W/kg and Wh/kg, not necessarily whats realistic/average/or even maybe possible (for instance the 5.65 kg / kWh is based on the EVE 304Ah cells, and clearly there is no way to build a 400AH battery from 304Ah cells). My math is not helpful in a practical sense here. In my mind I'm starting from the point of "assuming you used the most energy dense / efficient version possible of everything, is it feasible or realistic for a system like this to be 'portable'.

The 60lb, is based on using one of the most energy dense cells I am aware of (EVE 304Ah), and only accounts for the cells themselves, busbars, BMS, fuse, enclosure, etc will all add weight and bulk, pre-builts might be heavier as well, and likely bulkier.

 

[Richard295]

The batteries, BMS units, solar charge controllers, alternator DC to DC converter, AC to DC converter, and inverter can either be purchased primarily as a modular portable system or fully DIY built as a modular portable system. The major challenge appears to be solar panel mounting/portability; is it acceptable to build or buy solar suitcases to address solar panel portability significantly augmented by the alternator DC to DC?

25 year warranty glass 200W portable solar suitcases (~ 36 lbs) can be purchased. 25 year warranty DIY 420W portable solar suitcases (~50 lbs) could be built.

 

[Dzl]

The batteries, BMS units, solar charge controllers, alternator DC to DC converter, AC to DC converter, and inverter can either be purchased primarily as a modular portable system or fully DIY built as a modular portable system. The major challenge appears to be solar panel mounting/portability; is it acceptable to build or buy solar suitcases to address solar panel portability significantly augmented by the alternator DC to DC?

25 year warranty glass 200W portable solar suitcases (~ 36 lbs) can be purchased. 25 year warranty DIY 420W portable solar suitcases (~50 lbs) could be built.

The other major challenge is how to make the system portable, in a way that doesn't leave one RV gutted and worthless at the end of the port over from one to the next. To me that is the big challenge, and why I think probably this project won't be practical/worthwhile, unless the old RV's are going to be sold for parts/sent to the junkyard anyway. Or at least that is the way it seems to me, I've never owned an RV so not entirely sure how they are setup to operate.

 

[RVLiFe]

Design a system that can be easily mounted on a piece of plywood. This will give you the ability to remove it easily and transfer it to a different RV by simply unbolting it and disconnecting the batteries. This is what I did with my install. I can easily add additional batteries if need since I wired with 1/0 AWG. I installed an external solar input on the outside of my RV that can easily stay with the new owners. My panels are not mounted on top of my RV because I usually park under trees so I have 50’ of PV wire. I created a rack in the basement storage compartment for the panels that are attached with wing nuts to hold them in place on travel days. I could seriously uninstall everything in a matter of an hour at most. My system uses a hard wired connection from my inverter to my breaker box along with a transfer switch because that’s what I wanted but you could easily just run an extension cord from the inverter to your shore power. It’s as portable as it will ever need to be.

Have fun!

 

[corn18]

Hoping this will be of use to others. I have not settled on my ideal RV; but going solar with 6 months, 400ah bank, 12v, haven't sized panels yet, NH, shady, going to need something suitcase-ish even if it's homemade. To the question. Looking for examples or advice on how to construct a system where I can relatively easily move it from one RV to the next. Batteries will be either in a insulated heated cooler in the pass-through as I want to explore winter glamping, or under the bed, solar charger, inverter, BMS (internal to batteries?). Care about safety (will use the fire suppression sticks); and a 1/2 day remove and reinstall. Many thanks.

Every time I add something to my system, I think about what to do when I sell the trailer. I kept all the original bits and I can put it back to stock in about 8 hours. Except for the panels on the roof. I could take them off, but that would leave a bunch of holes in the roof. I could seal them nicely, but I were buying the trailer, I would rather have the solar panels than a bunch of holes.

But you got me thinking about the portability of a system. I could fit everything I need in a box and put it in the basement area or bed of my truck. Just plug the shore power cable into the box and run the RV that way. Wouldn't be too hard to do that way. But not the most efficient. But it would work. Just put all this in a box:



It has a female 50A RV outlet to plug in the RV. It also has a 50A inlet so you can plug it into shore power to charge the batteries while running the RV, too. Box would weigh 170 lbs, so not something you want to move around a lot, but could transfer from RV to RV fairly easily. Or make it weatherproof and put it in the bed of your truck (if towing).

Add connectors for solar panels and you're all set. Either use portable panels or put them on the roof.

 

[Dzl]

You guys are making me think maybe this problem is easier than it sounded. Sounds like keeping the system pretty isolated and just plugging into the RV's shorepower is pretty simple and straightforward solution that I was overcomplicating in my mind. So I suppose that covers the AC side. But how are you imagining tieing into the DC side and existing battery bank?

 

[corn18]

You guys are making me think maybe this problem is easier than it sounded. Sounds like keeping the system pretty isolated and just plugging into the RV's shorepower is pretty simple and straightforward solution that I was overcomplicating in my mind. So I suppose that covers the AC side. But how are you imagining tieing into the DC side and existing battery bank?

That's the inefficient part. The power box would only provide AC power. That would feed the existing RV converter/charger which would run the DC side of the RV. It would also charge the RV battery(s) which might not be desirable. You could just disconnect the factory RV batteries via the factory cutoff switch and power all the DC loads with the converter.

As far as the RV is concerned, the power box is just another AC power source. Having a 50A inlet on the box allows you to charge the box batteries from shore power. If you don't need to charge the box batteries, just hook the RV to shore power as normal.

This box really only works with an inverter/charger like the MPII 12/3000/2x120 50A. It can provide 240V 2 phase to power the entire 50A AC system. If you only plan to use 30A RV's, you can use a more affordable inverter/charger. Not sure how many new RV's are 30A these days. All of the big ones are 50A so they can run two air conditioners.

EDIT

Now that I thought about it a bit more, this could be a single phase 30A box. Just put 30A RV connectors on it and use any old inverter/charger for power. Hooking up a 50A RV shore power cord would require a dog bone, but that's easy. Put a 30A male inlet on it and plug that into shore power pedestal for charging and pass through. This would be a better match for a 400Ah system anyway.

 

[Dzl]

OP, out of curiosity, why will you be changing RV's every 3 to 6 months? And would it maybe just be best to hold off on buying/building a solar system until your situation is more stable, and use a generator in the interim?

 

[corn18]

OP, out of curiosity, why will you be changing RV's every 3 to 6 months? And would it maybe just be best to hold off on buying/building a solar system until your situation is more stable, and use a generator in the interim?

That's what I was thinking, too. A genset is portable, just noisier. I would love to build a portable power box. I could use it as a power backup for the house when we aren't camping. Just not sure how to lug 170 lbs around. Easy enough to put on wheels around the house, but getting it in/out of the truck bed or into the RV would be a problem.