Adding a 48v system to my travel trailer.

[TwoYearsonTwoSpyders]

OK this could get a bit long, please bear with me.
I have a mid size travel trailer, 23foot, that already has a 12v system in it. 340watt solar, a PWM 25v/30amp Zamp controller, 4 12v AGM batteries in parallel(not sure the size), and a 2000 watt Zantrex inverter. My trailer also has two 30 amp shore power input plugs. One at the front and one at the rear. Hear is my thoughts/plan:
1st- remove the heavy 340 watts of residential solar.
2nd- build a thin aluminum platform over the trailer to mount 8x200watt flex CIGS panels (ea. 31.5VOC/8.64A) in series.
3rd-install in tounge box 48V EG-4 3kW AIO inverter/ charger ( https://signaturesolar.com/eg4-3kw-...r2ooEFRdHYEsl9hcu-afUiL7PX8vjfHdggB4q3.VnU9vH )
4th Two 48V 100AH EG4 WP batteries.
This should give me a silent true 3000 watt solar gen. Here is where I need some input.
First I would like to keep the rest of the 12v system in place. So to feed the Zamp controller would I be able to feed 20-30 amps of 12-24v through a step down converter from the 48v batteries in place of the 340 watts of original solar panels I removed?
Second I would like to use the front 30amp shore power plug as the AC input to the EG4 3kW AIO inverter/ charger and treat the AC output of the inverter as the shore power to the trailer. I understand that the 3kW from the inverter wont equal the 3600watts from a 30A shore power supply. The EG4 3kW unit can handle 5kW surges, for starting the air conditioner.

Thanks all input welcome
Robert

 

[AnarchyJet]

Are the 2 30amp shore power inputs separated by a transfer switch or do they power isolated panels?
I would get a 48v -> 12v dc-dc charger to maintain your AGM's and ditch the PWM controller.
You might want to go 4s2p panel config if there is any chance of shading a panel.

 

[TwoYearsonTwoSpyders]

Yes the shore power plugs run through transfer switch so when pluged in I do not turn on the Zantrix inverter. The trailer then has its own charging system for the 12v batteries. If not pluged in the only charging the 12v sees is from the solar panels now that I was going to remove for weight savings and the fact that the CIGS would be covering the old panel area.

 

[HRTKD]

CIGS aren't proving to be very good performers. No way would I trade out working residential panels for CIGS.

 

[TwoYearsonTwoSpyders]

Well as you say residential panels do perform better, but as we learn on RVs there is 2 BIG limiting factors. First is weight. 340 watts of residential is around 60 to 80 pounds. Sorry I don't know exact #s. and the CIGS are 7 pounds for 200 watt panel. I am building a platform to fit 1600 watts or 8 panels to cover the roof of trailer. That is almost 5 times the wattage for about the same weight. I know the platform will probably about double that but it will serve as not only a way to adhere the CIGS, but also I am making it to be a heat sink to draw away and disperse the heat that might cause the panels to perform less than rated. The second is space on the roof of an RV that dose not already have something there. There is only room on my Oliver trailer to put about 200 more watts of residential panels spread out in multiple small panels. By going to the lighter CIGS on a light weight aluminum skin platform raised above the entire roof with all its AC and vent units I can put the 8 CIGS panels that measure 85.5 x 26 inches. That works out to be 208 x 86 inch platform witch matches my trailer almost perfect. This also helps in the summer to shade the whole trailer. I talked to the AC manufacture rep. and he stated this would help the air conditioner to keep the trailer cooled in the hot summer camping season.

 

[HRTKD]

Good luck with CIGS. I doubt you'll get anywhere close to the rated output.

My 320 watt residential panels from Mission Solar weigh 44 lbs.

 

[Scar]

The idle consumption on that AIO is gonna eat about a fifth to a quarter of the energy your panels produce assuming they actually work well, which despite costing you 4500 dollars, they won't for long. Honestly this just isn't practical on a 23 ft TT. You don't have the real estate for solar air conditioning unless you delete the rooftop unit and use a mini-split, even best case scenario you can expect to run your rooftop air conditioner for 3.5ish hours a day without other power draws. Any more and you're looking at an energy debt. This is from someone using the EG4 6500ex AIO, it works fine for me but I've got 2730w of rigid panels on my roof to offset the cost.

On the other hand you could save 4500 in panels and 1k in materials and hardware and just get a nice inverter generator and a lot of gas to top your batteries as needed.

 

[mikes68505]

Robert, I agree with Scar on idle consumption... you'll need 2-3 panels depending on run time, just to account for EG4 3kWh AIO idle consumption. No different than EG4 6500EX or others. Realistically, as all AIOs have higher IC, you just need to add to watts/panel calculations. If still pursuing the system as designed, you might consider building slides for the solar panels to double or triple the panels. I'm working on using Alrska 180-watt flexible panels (due to Length/Width dimensions, and weight), and preparing triple panel slides with actuators, goal is 4-6 sets.

For comparison, my design includes:
EG4 6000EX-48HV 120/240 Split Phase Inverter {AIO} (78lbs); this was also chosen for the requirements of the electric heating system I'm installing, which needs 15 amps per leg.
[noting from Will's testing the 6000EX shows 136 watts IC {or 3.2 kwt/day if running continuously).]
Dual EG4 5.12K 48V server rack batteries (tl of 203 lbs).
Also will be installing an EG4 Chargeverter (generator bay) for bad weather days and/or heavy consumption times. This will charge the batteries from the Onan 4k Generator I have onboard.
Will also need 48V-12V stepdown for 12v/DC stuff.

Sounds like you have more room for solar panel space. My main concern is the physical limitation of space, both on the roof and inside of 2022 GD Momementum 29G. My solar slide design above, minus efficiency loss, and IC loss, should do a decent job at charging my 10kWh of batteries.

Due to Momentum toy haulers having higher tongue weight, and having a heavy ProPride 3P hitch, already planning for the placement of the power system on storage shelves in the garage (adding reinforcement support/cabinets underneath). The drawback is the inverter is louder than others but I'll deal with that with soundproofing and side venting.

 

[Panhandler]

4th Two 48V 100AH EG4 WP batteries.


Thanks all input welcome
Robert

Robert, seems like you're getting good advice about the other components. I do not recommend the 48V 100AH EG4 batteries. I had two, one went into protect mode the first week and was impossible to get out of protect mode. SS suggested applying a 48v charger and stated there was a 50% chance of bringing the battery out of protect mode. $250+ is a lot for 50%.... I sent the battery back (not cheap either). I would strongly recommend a battery with external controls, something that you can manually reset if needed.

 

[Aussieguy]

"This should give me a silent true 3000 watt solar gen. Here is where I need some input."

your intended panels 8 x 200w if producing at 100% at most could "generate" 1600w
you are NOT making a generator that can produce 3000w

the inverter may allow you to consume 3000w from a battery
twice as fast as your generator can produce power
--------------------------------------------------------------------------------------------------
48v not needed in such a small system

check out Will Prowse's comments on the reliability and lifespan of the flexible panels
most trailer roof's can handle the weight of solid panels + some framework

 

[azozrider]

You want max power per square inch.

When you spread the weight across all the roof structure points, weight really isn't an issue. I have 12 -250W Sunpower panels on an elevated (aluminum) structure I built, with aluminum tilt frames, on the 24' of roof I have on my GD 24MPR Toy Hauler. No dramas at all. Think about it... most RV roofs are walk-on... meaning you are subjecting your roof structure to your body weight spread over only a few inches (your footprint).

You are likely to be super disappointed with the flexible panels. I've not met anyone in my travels who have them that said they will do it again. You can never have too much collection. Weather, orientation when parked, desire to use more than one appliance or gadget at a time... a ton of factors go into the reasons I personally feel that in an RV application, it's all about maximizing power per square inch. That is why I like SunPower... smallest footprint for the most output. I have another, much bigger 5th wheel now, and cannot elevate like I did on the bumper pull, so having to conceive of a way to get epic collection (Full time nomad). Ever meet anyone that says they wish they'd built a smaller system or had too many panels?

 

[mikes68505]

You want max power per square inch.

When you spread the weight across all the roof structure points, weight really isn't an issue. I have 12 -250W Sunpower panels on an elevated (aluminum) structure I built, with aluminum tilt frames, on the 24' of roof I have on my GD 24MPR Toy Hauler. No dramas at all. Think about it... most RV roofs are walk-on... meaning you are subjecting your roof structure to your body weight spread over only a few inches (your footprint).
You are likely to be super disappointed with the flexible panels. I've not met anyone in my travels who have them that said they will do it again. You can never have too much collection. Weather, orientation when parked, desire to use more than one appliance or gadget at a time... a ton of factors go into the reasons I personally feel that in an RV application, it's all about maximizing power per square inch. That is why I like SunPower... smallest footprint for the most output. I have another, much bigger 5th wheel now, and cannot elevate like I did on the bumper pull, so having to conceive of a way to get epic collection (Full time nomad). Ever meet anyone that says they wish they'd built a smaller system or had too many panels?

Azozrider... appreciate this response... been a minute since on this site... wanting to follow up. I ended up going fixed panel, and with RICH Solar 200w 24V panels (due to vmp needed for EG4 3K Invertors. Starting with 8 with 4 in series for each inverter to get above 120v needed. Eventually will add others when I get the design and aluminum welding needed to create slides with actuators. Goal is to get to enough solar to charge 10kWh battery bank in single day.

Other challenge now working on is 1) 48v-12v converting components, and 2) starting the generator. Slowly but surely solving each.
-m

 

[bill_zunderman]

Goal is to get to enough solar to charge 10kWh battery bank in single day.

My van with 720W of flat rooftop solar has most recently maxxed out at 3.1 kWh/day in early Aug. That's only production, and with offsetting active loads it might only charge about 20% of my 11kWh battery. I'm up at 45 deg N, so there are much better latitudes for more solar. Depending how your panels are mounted, you might need >2000W of solar to reach 10kWh of production a day.

 

[mikes68505]

My van with 720W of flat rooftop solar has most recently maxxed out at 3.1 kWh/day in early Aug. That's only production, and with offsetting active loads it might only charge about 20% of my 11kWh battery. I'm up at 45 deg N, so there are much better latitudes for more solar. Depending how your panels are mounted, you might need >2000W of solar to reach 10kWh of production a day.

Yes, I've estimated a minimum of around 2200 (three more panels) but working toward 6 as the day's working load will certainly reduce charging. And that each EG4 3k unit will likely take a panel's worth for its consumption.

 

[mikes68505]

You want max power per square inch.

When you spread the weight across all the roof structure points, weight really isn't an issue. I have 12 -250W Sunpower panels on an elevated (aluminum) structure I built, with aluminum tilt frames, on the 24' of roof I have on my GD 24MPR Toy Hauler. No dramas at all. Think about it... most RV roofs are walk-on... meaning you are subjecting your roof structure to your body weight spread over only a few inches (your footprint).

You are likely to be super disappointed with the flexible panels. I've not met anyone in my travels who have them that said they will do it again. You can never have too much collection. Weather, orientation when parked, desire to use more than one appliance or gadget at a time... a ton of factors go into the reasons I personally feel that in an RV application, it's all about maximizing power per square inch. That is why I like SunPower... smallest footprint for the most output. I have another, much bigger 5th wheel now, and cannot elevate like I did on the bumper pull, so having to conceive of a way to get epic collection (Full time nomad). Ever meet anyone that says they wish they'd built a smaller system or had too many panels?

Question if I may on aluminum frame structure... would like to hear about that, what tools did you use for welding aluminum, etc. TIA.

 

[Dave_11]

You want max power per square inch.

When you spread the weight across all the roof structure points, weight really isn't an issue. I have 12 -250W Sunpower panels on an elevated (aluminum) structure I built, with aluminum tilt frames, on the 24' of roof I have on my GD 24MPR Toy Hauler. No dramas at all. Think about it... most RV roofs are walk-on... meaning you are subjecting your roof structure to your body weight spread over only a few inches (your footprint).

You are likely to be super disappointed with the flexible panels. I've not met anyone in my travels who have them that said they will do it again. You can never have too much collection. Weather, orientation when parked, desire to use more than one appliance or gadget at a time... a ton of factors go into the reasons I personally feel that in an RV application, it's all about maximizing power per square inch. That is why I like SunPower... smallest footprint for the most output. I have another, much bigger 5th wheel now, and cannot elevate like I did on the bumper pull, so having to conceive of a way to get epic collection (Full time nomad). Ever meet anyone that says they wish they'd built a smaller system or had too many panels?

The problem I'm finding during my planning phase is that the trailers they are manufacturing these days often have extremely low cargo capacity. I'm not concerned about weight structurally on the roof, I'm concerned about exceeding the GVWR of the trailer. I'd love to do a rigid panel build with tilt bars built in, but just don't have the cargo capacity to do it. This unfortunately is the only reason I'm personally looking at flexible panels.

 

[HarryN]

I build both 24 and 48 volt mobile power systems for trailers and vans.

IMHO - unless you really need the 48 volt aspect -strongly consider instead to go 24 volt.

While I do really love 48 volt systems, one of the larger DC loads in a trailer is the compressor refrigerator and those are very commonly dual 12 / 24 volt. Similarly LED strip lighting, fuel heaters, etc are very commonly available in 24 volt.

The whole blue sea web site of stuff is all 24 volt compatible but none of it is 48 volt compatible, same for nearly everything in a marine store or supply line.

There is an inverter efficiency improvement going from 24 - 48 volt, but not nearly as much as the move from 12 - 24 volt.

There is nothing at all wrong with 48 volt systems - I build them routinely - but it took me a long time to work out some of the details and it is those little details that can really slow down a project.

 

[HarryN]

The problem I'm finding during my planning phase is that the trailers they are manufacturing these days often have extremely low cargo capacity. I'm not concerned about weight structurally on the roof, I'm concerned about exceeding the GVWR of the trailer. I'd love to do a rigid panel build with tilt bars built in, but just don't have the cargo capacity to do it. This unfortunately is the only reason I'm personally looking at flexible panels.

I would not put tilt on your trailer -especially if you have one with the very low GBWR of most modern trailers like Jayco or similar.

To be honest - those are so deceptive that I am not sure how they are allowed.

Anyway - do what you can with solar facing up on the roof and if you need to - consider to mount some panels on the side of the trailer vs tilting.

 

[bill_zunderman]

I build both 24 and 48 volt mobile power systems for trailers and vans.

IMHO - unless you really need the 48 volt aspect -strongly consider instead to go 24 volt.

While I do really love 48 volt systems, one of the larger DC loads in a trailer is the compressor refrigerator and those are very commonly dual 12 / 24 volt. Similarly LED strip lighting, fuel heaters, etc are very commonly available in 24 volt.

The whole blue sea web site of stuff is all 24 volt compatible but none of it is 48 volt compatible, same for nearly everything in a marine store or supply line.

There is an inverter efficiency improvement going from 24 - 48 volt, but not nearly as much as the move from 12 - 24 volt.

There is nothing at all wrong with 48 volt systems - I build them routinely - but it took me a long time to work out some of the details and it is those little details that can really slow down a project.

Yeah - I've been modifying the 48V Volta system that my van came with, and in the process of upgrading most of their components. Doing anything on the 48V bus is a pain - finding fuses or switches that are actually rated for 58V+ takes a lot of time and is usually special order. For a motorhome 48V makes sense as the alternators can charge in the 6-10kW range, but you don't see many travel trailers that charge via secondary alternator. Volta built one as a demo, but I'm sure no one really wants to pay their prices. The risk of an alternator load dump of hundreds of volts instantly zapping everything does give me some fear, and it's frustrating that no one actually sells a 48V suppressor. Only benefit I can envision in a 48V travel trailer would be recharging from a generator through an EG4 chargeverter at 5kW. You could custom build a charger that would do similar on 24V, but most probably wouldn't be interested in doing that. When I'm done upgrading the system I'll probably even install a 24V converter as many of those little USB charger sockets can actually charge a laptop and other USB-PD devices if you toss 24V at them. They can buck the 24V to 20V for the 20V-5A (100W) USB charging profile.

 

[mikes68505]

You want max power per square inch.

When you spread the weight across all the roof structure points, weight really isn't an issue. I have 12 -250W Sunpower panels on an elevated (aluminum) structure I built, with aluminum tilt frames, on the 24' of roof I have on my GD 24MPR Toy Hauler. No dramas at all. Think about it... most RV roofs are walk-on... meaning you are subjecting your roof structure to your body weight spread over only a few inches (your footprint).

You are likely to be super disappointed with the flexible panels. I've not met anyone in my travels who have them that said they will do it again. You can never have too much collection. Weather, orientation when parked, desire to use more than one appliance or gadget at a time... a ton of factors go into the reasons I personally feel that in an RV application, it's all about maximizing power per square inch. That is why I like SunPower... smallest footprint for the most output. I have another, much bigger 5th wheel now, and cannot elevate like I did on the bumper pull, so having to conceive of a way to get epic collection (Full time nomad). Ever meet anyone that says they wish they'd built a smaller system or had too many panels?

Way Long delay just getting back on this site... wanting to note that I did go with aluminum fixed panels, best fit was Rich Solar 24v, due to dimensions and space. Actually now enough space to put 9th panel... to be used singularly for charging the 12v battery maintained for starting generator.

 

[JS43]

Good luck with CIGS. I doubt you'll get anywhere close to the rated output.

My 320 watt residential panels from Mission Solar weigh 44 lbs.

Yup, my 415w panels are 50lbs each. Have 8 on top of my 35' TT.

 

[mikes68505]

Yup, my 415w panels are 50lbs each. Have 8 on top of my 35' TT.

FYI, not sure to which post added it to... but did end up going with Rich Solar 200w fixed 24v panels, 8 panels 4S2P (150v...10 amps).