Jump to content

Solar 12V or 24V system


Ken

Recommended Posts

I know most rver's use 12v, but what would be wrong with using a 24 volt system. I assume that 24v is used mostly on off-grid locations. What would be the negatives of installing a 24 volt system on an rv.

 

Thanks for you input

Ken

Link to comment
Share on other sites

The only real negative is having to provide 12 volts for your house needs.  And the biggest issue in that is getting enough power for you high current loads. Many of the DC/DC converters will not supply high enough output for slide motors - especially hydraulic ones. But it can certainly be done.....

Jack & Danielle Mayer #60376 Lifetime Member
Living on the road since 2000

PLEASE no PM's. Email me. jackdanmayer AT gmail
2016 DRV Houston 44' 5er (we still have it)
2022 New Horizons 43' 5er
2016 Itasca 27N 28' motorhome 
2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU
No truck at the moment - we use one of our demo units
2016 smart Passion, piggyback on the truck
-------------------------------------------------------------------------
See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar power
www.jackdanmayer.com
Principal in RVH Lifestyles. RVH-Lifestyles.com

Link to comment
Share on other sites

 One Negative is that most RV loads like lights,, and water pumps,, and vent fans,,,and those 12 VDC cigarette lighter type of outlets and their loads ,,, and power to appliances,,, are 12 VDC NOT 24 and I don't see using two loads in series (for a 24 volt system) as a great solution. Ifffffffffff ?? the RV has some high current 24 volt devices/appliances then I might see some advantages.

  I take you're NOT talking about 12 or 24 volt solar panels as that's a different question. I am using 24/30 volt panels as it (higher voltage)  reduces the current I carry down to my solar charge controller.

  TRUE higher voltage = less current for the same power, BUT I cant think of many Positives for using 24 volts (and any necessary conversions) in an RV with ONLY 12 volt appliances, maybe other fine gents can enlighten us as were never too old to learn.

 John T   NOT a Solar Expert by any means 

 

Link to comment
Share on other sites

I am talking about using 24v panels like the ones used in off-grid systems.

The guy I am using does a lot off-grid systems and some rv's. His panels are 290 watt hyundai.

They are large panels.

I know of one other rv system he has installed using these panels and they are very happy with that system.

The other system has a lot more batteries than I will.

I am located in NW Arkansas.

Ken

Link to comment
Share on other sites

  Ken, thanks for the clarification. From reading your original post I couldn't be sure if your were talking 24 volt distribution or 24 volt panels SORRY.

  FWIW I have 24/30 volt panels and prefer them over my past RV which used 12 volt panels. The higher the panel voltage the less current (for same power) you have to transmit down to your solar charge controller. Passing current through conductors causes  an I x R voltage drop and wasted I Squared R heat energy loss, when Id prefer it be delivered to my charge controller instead. While bigger = better always rings true for reduced voltage drop, you can get by with smaller cables as the source voltage rises. As I recall my solar charge controller can accept up to 150 volts input, some are 12 or 24, some are 12 or 24 with auto detection and switching. SO LONG AS your solar charge controller can work with 24 volt and above voltage input, I SEE NO PROBLEM USING 24 (actually prefer) volt panels like I did.

NOTE the solar charge controller takes that raw energy, be it 24 or 48 etc or higher voltage from the solar panels, and converts it to 13 to 14+ or so volts to charge your 12 volt batteries. IE because you have 24 or 48 or more solar panels does NOT mean your RV still don't run on a 12 volt system. That's the job of your solar charge controller. 

 I'm NOT a solar expert so see if any of them find negatives from the use of 24 volt panels

PS with multiple panels you get into the whole series versus parallel versus series/parallel combinations and sun and shading and all that, but I still don't see many negatives using 24 volt panels 

 

 John T

Link to comment
Share on other sites

If I had to guess, I would say most of the larger solar systems in use by members on this forum use higher voltage panels.  The panels I have in my system are rated at 29.8 volts.  Using higher voltage panels charging a 12 volt battery bank will limit you to an MPPT controller (which is a better choice in my opinion).  PWM controllers are limited to 24 volt panels when charging a 12 volt battery bank.

As John states, higher voltage panels can help with voltage loss in your wiring. The MPPT controller can also use that excess voltage to put more amperage into your batteries at 12 volt.

2000 Kenworth T2000 w/ Cummins N14 and autoshift
2017 DRV Mobile Suite 40KSSB4 with factory mods, dealer mods and personal mods - now in the RV graveyard
2022 DRV Full House MX450 with customized floor plan
2018 Polaris RZR Turbo S (fits in the garage)
2016 Smart Car (fits in the garage or gets flat towed behind the DRV when the RZR is in the garage)
My First Solar Install Thread
My Second Solar Install Thread & Photos and Documents Related to the build
My MX450's solar, battery and inverter system - my biggest system yet!

chadheiser.com      West Coast HDT Rally Website

event.png    

AZCACOIDIAKSMNMOMTNENVNMNDOKSDTNTXUTWYxlg.jpg

 

Link to comment
Share on other sites

There is a bunch of info on the ins/outs of higher voltage panels on my website. If you are not talking about a 24 volt battery system it is a totally different topic. 

Jack & Danielle Mayer #60376 Lifetime Member
Living on the road since 2000

PLEASE no PM's. Email me. jackdanmayer AT gmail
2016 DRV Houston 44' 5er (we still have it)
2022 New Horizons 43' 5er
2016 Itasca 27N 28' motorhome 
2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU
No truck at the moment - we use one of our demo units
2016 smart Passion, piggyback on the truck
-------------------------------------------------------------------------
See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar power
www.jackdanmayer.com
Principal in RVH Lifestyles. RVH-Lifestyles.com

Link to comment
Share on other sites

Most residential solar systems operate at 24 or 48 volts and supply power to the house with a 230 volt A/C inverter.  Higher voltage residential panels tend to be fairly large and the higher voltages are more efficient and use smaller wiring.  I believe almost all RV systems are based on 12 volt panels.  The smaller panels do better on the roof of an RV with less wind lift and flexing.  Even for 12 volt panels you want relatively small panels and not the biggest available.  Typically you want more panels because of shading either due to roof appliances and vents or do to shading from trees.  A very small amount of shading serious kills the output of any solar panel.  12 volt panels are typically connected in parallel but for some RVs, pairs of two panels are wired in series which doubles the voltage.  You can use smaller wiring but you need a more powerful MPPT controller that will handle the higher voltages.  The disadvantage of series wiring is again related to shading.  If either of two panels wired in series has even relatively minor shade, then the output of both panels is affected.    The typical recommendations would be to use more and smaller panels to reach the desired total wattage.  That does mean you will need somewhat larger wiring but nothing excessive. 

Link to comment
Share on other sites

 Good afternoon Jim K,  you state  " I believe almost all RV systems are based on 12 volt panels"

Dagnabbit lol story of my life being different grrrrrrrrrrrr and here I done went and based my system on 24/30 volt panels wired in parallel to reduce shading problems, but I'm just an old nerdy engineer.. It seemed like a good idea to me and my MPPT charge controller can handle up to 150 volts.

Oh well its working fine so no need to change and to each their own I reckon

Nice chatting with you, take care now

John T

 

Link to comment
Share on other sites

I use a pair of 325 watt 48V panels wired to my MPPT solar controller.  The higher voltage allows me to use a smaller wire size to go from my combiner box to my controller. 

As Jack said, go to his website for lot of great info.

Al & Sharon
2006 Winnebago Journey 36G 
2020 Chevy Colorado Toad
San Antonio, TX

http://downtheroadaroundthebend.blogspot.com/

Link to comment
Share on other sites

On ‎6‎/‎4‎/‎2017 at 2:31 PM, oldjohnt said:

 Good afternoon Jim K,  you state  " I believe almost all RV systems are based on 12 volt panels"

Dagnabbit lol story of my life being different grrrrrrrrrrrr and here I done went and based my system on 24/30 volt panels wired in parallel to reduce shading problems, but I'm just an old nerdy engineer.. It seemed like a good idea to me and my MPPT charge controller can handle up to 150 volts.

Oh well its working fine so no need to change and to each their own I reckon

Nice chatting with you, take care now

John T

John, I am not sure but it sounds like you are being facetious.  Since you are engineer I am sure you put together a great system.  My comments about sticking to smaller 12 volt panels reflect recommendations found at amsolar and some other solar equipment distributors. 

 

 

Link to comment
Share on other sites

Yo Jim,

  NOPE I wasn't intending to be facetious, its ONLY that's the story of my life lol many do things one way like you were talking about but sillyyyyyyyy meeeeeeeee I'm often different grrrrrrrrrrr. My very first system was indeed 12 volts but with a different RV and our local supplier offering the 24 volt 245 watts panels at 90 cents per watt that's the route I chose. I'm happy to agree its still working great even if NOT as you claimed  "almost all RV systems are based on 12 volt panels"

Best wishes now and take care

 John T

 

Link to comment
Share on other sites

We also use 24v panels and have no problem. The only drawback is needing an MPPT controller rather than a PWM type. MPPT controller are quite a bit more expensive. OTOH you get much more of the power that hits your panel to go into your battery. We use 200watt panels that are only slightly bigger than the 160 watt 12 volt panel we started out with on our garage. They are Hanwha and are much more solidly built and stronger than the 12v panel. Not sure if that is a generalization or just those particular panels. I think they would go on the roof just fine but we have them free standing so we can catch the "summer" sun in Canada. Really need to maximize your solar inout since we have many more cloudy/partially cloudy days than our winters in  arizona.

Link to comment
Share on other sites

Good Morning Kinsey,

FWIW I agree with your statement  "The only drawback is needing an MPPT controller rather than a PWM type. MPPT controller are quite a bit more expensive. OTOH you get much more of the power that hits your panel to go into your battery."

Having used BOTH PWM and MPPT solar charge controllers, I have an MPPT now and Id NEVER GO BACK. Of course, to each their own opinions preferences and budget as both still indeed work under the right circumstances.  

Have a good one, safe travels

John T

 

 

Link to comment
Share on other sites

Several have commented that MPPT controllers are more expensive .

I do not have a solar system but have worked with the renewable energy world, some years back, mostly wind, on & off Grid. That being said what I see in present cost of MPPT controllers and there efficiency makes there use very affordable when installing a system as extra solar panels are not cheap to get to the same result.

One thing not mentioned is any preferred brands to buy or stay away from. I prefer some American labor in the products I buy.

Clay

 

 

Clay & Marcie Too old to play in the snow

Diesel pusher and previously 2 FW and small Class C

Link to comment
Share on other sites

38 minutes ago, ms60ocb said:

I prefer some American labor in the products I buy.

There aren't too many around, but here are a few I am aware of that are either assembled in the U.S. or will do so upon request.

Suniva, Solarworld, Gigawatt and Sunspark are "mainly" sourced and assembled in the U.S. Grape solar is "mainly" sourced outside of the U.S., but will do assembly in the U.S. if requested.

Suniva's generally have a little better price point than Solarworld, however, Solarworld would be the best in sourcing and manufacturing in the U.S. Personally... I am a little partial to Grape solar. Some of their panel efficiency ratings are some of the best on the market, but you have to do your due-diligence since their product line is so varied. "Economy" panels are their mainstay, but they DO have some very nice offerings as well.

I don't mean to generalize, but the difference in their PV's quality levels being sourced out of China vs. Japan is about what you might expect if you're into stereotypical type thinking. Just sayin...

Link to comment
Share on other sites

  • 2 months later...

Read every post on this thread. It looks as if more folks are going to 24 V and 48 V (nominal) battery suites. Advantages as pointed out by others in thread are using a much lower amperage MPPT and loss of power in transmission from roof.

We have a 48 V (nominal) battery suite and energy is provided to 5th wheel via 

4.0 kW PSWI

500 W 48V to 12 V Meanwell converter.

Reed and Elaine

Link to comment
Share on other sites

23 hours ago, reed and elaine said:

Read every post on this thread. It looks as if more folks are going to 24 V and 48 V (nominal) battery suites. Advantages as pointed out by others in thread are using a much lower amperage MPPT and loss of power in transmission from roof.

We have a 48 V (nominal) battery suite and energy is provided to 5th wheel via 

4.0 kW PSWI

500 W 48V to 12 V Meanwell converter.

Reed and Elaine

I've been looking at 48VDC battery bank.

Does the Meanwell 500 charge a battery or directly into the 12V distribution?

Do you have a battery monitor on the 48v battery bank?

What kind of leveling system do you use?  I was checking the draw on Bigfoot leveling today. Each pump draws upwards of 50amps@12VDC.

 

2011 Cameo 34SB3

Link to comment
Share on other sites

J-T

Our 48 V (nominal) system is four Manzanita Micro Lithium-Iron-Phosphate (each battery is four x 3.2 V nominal CALB cellsi n series. The battery suite has a number of monitors: Magnum Inverter Monitor, the Manzanita Micro BMS monitor, and the Tri-Star MPPT  control monitor. One can get OCD observing these things.

The Mean Well goes directly to 12  distribution. Meanwell produces converters to 1 kW. Not sure if they have a 48 V to 12 V with this rating

Leveling system on our Open Range 337RLS is four electrically driven worm-screw jacks. It is supposed to be automatic but we prefer to run them manually.  These probably require a lot less power than does hydraulic pumps. However, our son did rewire when he fabricated this system. He used the Mean Well to operate from the LFP battery suite but left the original AC-DC converter connected to the 5th wheel's AC and this is used only to operate the worm-screw jacks.

If we can be of further help, let us know. Jack Mayer is the real professional on this thread

Reed and Elaine

 

Link to comment
Share on other sites

1 hour ago, reed and elaine said:

J-T

Our 48 V (nominal) system is four Manzanita Micro Lithium-Iron-Phosphate (each battery is four x 3.2 V nominal CALB cellsi n series. The battery suite has a number of monitors: Magnum Inverter Monitor, the Manzanita Micro BMS monitor, and the Tri-Star MPPT  control monitor. One can get OCD observing these things.

The Mean Well goes directly to 12  distribution. Meanwell produces converters to 1 kW. Not sure if they have a 48 V to 12 V with this rating

Leveling system on our Open Range 337RLS is four electrically driven worm-screw jacks. It is supposed to be automatic but we prefer to run them manually.  These probably require a lot less power than does hydraulic pumps. However, our son did rewire when he fabricated this system. He used the Mean Well to operate from the LFP battery suite but left the original AC-DC converter connected to the 5th wheel's AC and this is used only to operate the worm-screw jacks.

If we can be of further help, let us know. Jack Mayer is the real professional on this thread

Reed and Elaine

 

Thank you.

Is the battery for your trailer emergency brakes charge from the tow vehicle? 

I thought you may have a different way of powering Bigfoot pumps.

With the +/-100amp 12VDC draw from the Bigfoot and wanting to keep the (58VDC) panels in parallel (snow/shading) I'm 96% sure I'll  be sticking with 12VDC.

If I was going to order a new trailer I'd go with 48VDC LifePO4 and use 110VAC hyd. pumps for the Bigfoot system.

Yes, Jack is a wealth of information.

 

2011 Cameo 34SB3

Link to comment
Share on other sites

J-T

 

The battery for trailer emergency brakes is the LFP solar powered battery suite. Grandson ran the rear view video through the 12 V power pin on the pig tail.

As noted earlier, the landing legs are electric motor powered screw jacks. These can be operated manually with a crank.

I think more folks are going to 48 V (nominal systems).

Jack knows the theory far better. We are just anecdotards with a sizeable amount of experience on the road: Most quite good and some, not quite as good

Reed and Elaine

Link to comment
Share on other sites

On 8/22/2017 at 8:30 PM, J-T said:

If I was going to order a new trailer I'd go with 48VDC LifePO4 and use 110VAC hyd. pumps for the Bigfoot system.

Or, use 48vDC pumps. 

Jack & Danielle Mayer #60376 Lifetime Member
Living on the road since 2000

PLEASE no PM's. Email me. jackdanmayer AT gmail
2016 DRV Houston 44' 5er (we still have it)
2022 New Horizons 43' 5er
2016 Itasca 27N 28' motorhome 
2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU
No truck at the moment - we use one of our demo units
2016 smart Passion, piggyback on the truck
-------------------------------------------------------------------------
See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar power
www.jackdanmayer.com
Principal in RVH Lifestyles. RVH-Lifestyles.com

Link to comment
Share on other sites

Both Jack and J-T have mentioned the hydraulic pumps for the Bigfoot jacks. How many watts do they draw? As noted above, we have electrical motor driven screw jacks for the Open Range 5th wheel we own and it does not draw that much power. To be noted is that our son left the original 120V AC to 12 V DC converter in for this purpose, and only this purpose. Jack suggested 48 V DC pumps, so there are a number a ways to do this with a 48 V battery system.

Reed and Elaine

 

 

T

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

RVers Online University

campgroundviews.com

RV Destinations

Find out more or sign up for Escapees RV'ers Bootcamp.

Advertise your product or service here.

The Rvers- Now Streaming

RVTravel.com Logo



×
×
  • Create New...