I am about to install a 56kwh solar project and have a few questions

[Cyberoamer]

I am about to install a large solar project in my 45' diesel pusher so we can boondock frequently and comfortably. My goal is to use the generator as infrequently as possible while still being able to run all three of our AC units and other powered items. I wanted to ask a few questions from a solar geek who isn't financially invested in this project!

Why 48v?
Do I need two inverters like quoted but why?
Can I go cheaper than Victron or should I buy once, cry once?
Anything I am missing?
The shop has great references for solar projects and they are their expertise as an FYI.
The pricing looks ok compared to what I researched...

Any thoughts?? Thanks in advance!

[Kirk W]

Welcome to the Escapee forums! The quote sheet that you posted is not clear enough to read but I was able to make out the price of $24,421.03. Since I have no experience with solar systems of that size, I suggest that you take some time to visit the site of one of our members who does have a long history of solar design. Chad Heiser is a member of the forums and hopefully will have time to advise you here, but his website, Heiser RV Solar & Electric has a great deal of very helpful information. 

[palmeris]

Can't read the quotes   try to attached or insert as a pdf .

Ohms law. 48v because higher voltage is lower current which allows for smaller guage wire. Kwh storage is volt x amp hours so you also get more kwh from 48 volt than 24 or 12

2 inverter typically configuration in split phase for 240 volt output , does your coach have 240 appliances?

Victron is good equipment,  tried and true. All components can communicate to each other and provide data to end user via display ,Bluetooth, or internet 

[GlennWest]

I have 4500 watts of panels. My battery 48v. I like not having  to use monster cables. Actually using a Chinese 48/12 converter. It has performed well. As long as we are in mild temps we use no park power. We are in South Texas now. Cool nights, no AC use, and hot days. 90s. Lots of sun. Mini split acs during daylight and off at night. Our battery at 55 volts in morning and fully charges up by noon.

[lappir]

2 hours ago, Kirk W said:

Welcome to the Escapee forums! The quote sheet that you posted is not clear enough to read but I was able to make out the price of $24,421.03. Since I have no experience with solar systems of that size, I suggest that you take some time to visit the site of one of our members who does have a long history of solar design. Chad Heiser is a member of the forums and hopefully will have time to advise you here, but his website, Heiser RV Solar & Electric has a great deal of very helpful information. 

Chad used to not want to do anything above 12 volt. Not sure if that's still the same. He is a wealth of information on 12 volt and a talented installer. 

 

Rod

[Randyretired]

When you say you want to use all 3 AC's that is a tall order and there isn't enough roof space for panels to be able to do that for very long on an RV.  RV AC's are not efficient at all and need lots of power.  We have a 40' Teton and we changed to a mini split.  These use as much as 1/4 the amount of power for comparable cooling.  Trying to run 3 RV AC's with solar will likely be disappointing.  Even one RV AC from solar is difficult.

48v batteries use smaller wire for the same amount of power so there is a little savings there but the big benefit is the savings on charge controllers.   It typically takes 4 times the controllers for the same array at 12v.  This of course means more equipment to provide for 12v necessities but still there are savings.

Victron is a quality brand and it typically comes with lots of displays for the status of the solar system.  It is not the only provider but it is popular with RV's.

Edited Sunday at 03:40 PM by Randyretired

[GlennWest]

I running low amperage with my system. High voltage. So lots of savings on solar controllers and wiring.

[GlennWest]

Randy correct. You will not run 3 RV acs with solar. They pull too much power. I have 2 12k mini splits. I cannot run both units 24 hrs on solar and battery. And they use way less than yours. One of yours use as much as both of mine and possibly more. I am using no park power now. But night temps in low 60s. I could add more battery but not enough solar to charge more and no more estate left up top. Just so much one can do with an RV. I really like 48v. Know Chad uses 12v only but you have lot more options with 48v. Lower cost also. I have no regrets going with 48v. Now a few people have put panels on slides. Double capacity. Lot of work too. 

Edited Sunday at 04:49 PM by GlennWest

[Randyretired]

I use 12v but only because our RV already had a workable inverter and wiring.  I use economics to determine the battery voltage.  It is possible to build a 12v system that is just as efficient as a 48v system but starting from scratch economics favor 48v for large systems but it also adds some complexity. 

[Cyberoamer]

3 hours ago, palmeris said:

Can't read the quotes   try to attached or insert as a pdf .

Can't upload a PDF file. The size restrictions for images is so small if I shrunk the quote to fit it would be unreadable so I provided a link to access the PDF. Very appreciative of everyone's time!

https://we.tl/t-dLAcZBS7JI

[GlennWest]

One could leave 12v side alone and still go with 48v for system. If I had hydraulic levelers and slideouts I would have left 12v battery in just for 12v use. My levelers are electric. My little Chinese 48/12 converter runs slideouts hydraulics fine.

Edited Sunday at 05:27 PM by GlennWest

[Cyberoamer]

2 hours ago, GlennWest said:

I have 4500 watts of panels. My battery 48v. I like not having  to use monster cables. Actually using a Chinese 48/12 converter. It has performed well. As long as we are in mild temps we use no park power. We are in South Texas now. Cool nights, no AC use, and hot days. 90s. Lots of sun. Mini split acs during daylight and off at night. Our battery at 55 volts in morning and fully charges up by noon.

Huge thanks. Makes perfect sense and I appreciate the time.

[Cyberoamer]

I can do it this way as I can't upload a PDF, the file size restriction of 275k is so tight if I shrunk the quote to that size, it'd be unreadable. I provided it as a link and the post was hidden for moderator approval so let me try this...

I have atttached it as a JPEG in the hopes this works. Thanks everyone!

[GlennWest]

Now that I can read it those 2 inverters only give you 6000 watts. 50 amp circuit gives you 12000 watts. I have 13000 watts of inverters capable limited by my 50 amp breaker.

[Cyberoamer]

55 minutes ago, GlennWest said:

ow that I can read it those 2 inverters only give you 6000 watts

this is the type of info I was hoping to get. I'll get them to update them, thanks!!

[Randyretired]

Now that I can read this it is for four 100ah 48v batteries and 3,000 watts of solar.  This is a nice size to run most of the appliances in an RV except AC's.  With this system you will need a generator  for most of the time running AC's.  I just spec's a very comparable system for a small cabin.  It works great for Starlink, residential refrigerator,  water pump, TV and occasionally the microwave or air fryer.  Updated I now see 4 batteries.  That is much better than I originally thought.  It will support some AC time.

 

Edited Sunday at 11:31 PM by Randyretired

[Chad Heiser]

The system costs are within reason for a system that size.  However, if the installer is telling you that it will run all three of your air conditioners they are feeding you a line of BS.  It will run two AC's but the solar production will only keep up with one AC running.  The inverters will each handle one AC at a time (assuming easy starts are installed on the ACs). 

In other words, you will be at a deficit and draining the batteries whenever you run more than one AC at a time in full sun.  At night, with no solar production you will be draining the batteries running the air conditioners.  Each AC will draw about 35 amps (give or take) at 48 volt to run with an inverter.  With 400 amps of 48 volt capacity, that is about 11 hours of run time for one AC by itself.  That does not account for any of the other things in your rig that will also be powered and drawing energy from the batteries.  Running two AC's will take that down to about 5.5 hours, again assuming the batteries started at 100% and are drawn down to 0% with no other draws on the batteries and no charge source active (no solar at night).  During the day, the solar will offset these numbers by the number of amps it produces.

I don't see anything in the quote about how all your standard 12 volt loads will be powered.  There is no converter listed to go from 48 volt to 12 volt.  Based on this, I assume the installer plans to leave your 12 volt system in place to power those loads (lights, jacks, slides, etc.).  This means you will be maintaining three electrical systems (actually four for a motorhome) in your rig.  You will have the 120 volt system, the 12 volt system for the house, the 12 volt system for the chassis and now the 48 volt system for the inverters/solar.  You will need some way to charge all three of the DC systems.  The solar will charge the 48 volt system and the alternator will charge the chassis 12 volt system, but how are they proposing to charge the OEM house 12 volt system?  Do they plan to leave the OEM converter in place and have the inverters charge the 12 volt system via the converter?  This will be a constant load on the 48 volt system that will have to be accounted for.  

I have lots of other questions and comments I could ask/make, but this should at least get the conversation started.  I have a lot of information on my website listed in my signature about RV solar.  Feel free to take a look.  I am happy to answer any specific questions you might have as well.  I would also be happy to talk with you off line if you want to contact me directly.

I will leave the 48 volt vs 12 volt conversation for later if you would like to get into that as well.  I also have a link to the system I have in my RV in my signature.  It is capable of running all three rooftop air conditioners at once.  In fact, I can literally turn on every 120 volt appliance in my rig at the same time and run them all (albeit for a limited amount of time).  This is because the system is built around two 5000 VA inverters instead of two 3000 VA inverters.  A 50 amp power pedestal has a potential power output of 12000 watts.  My system has a potential power output of 10000 watts (just 2000 watts shy of the pedestal).  The limiting factor for me is solar production and battery capacity.  My system is 12 volt based because my RV is 12 volt based.  I am not a fan of maintaining multiple system voltages (above and beyond the two OEM systems of 12 volt and 120 volt) in an RV for most people.  I'll leave it here for now since this is getting to be a long post.

[Cyberoamer]

17 minutes ago, Chad Heiser said:

have lots of other questions and comments I could ask/make, but this should at least get the conversation started.

Thanks, Chad. I would like to chat and, perhaps, hire you to go through the design with the installer and work with me to make recommended changes where requested, as the installation won't start for a few weeks. Is this a possibility, Chad?
I went through your current diagram. I see what they are missing.

[Chad Heiser]

I sent you a message with my phone number.  Feel free to give me a call.

[Cyberoamer]

Thanks for so much time on the phone today @Chad Heiser! I'm happy I can hire you hourly to chat with my chosen vendor and installers to make the changes we discussed. I feel like I'll have a much better end result.