what is a better set up - in General

[Sheldon-M]

4 lithium-100 amp H batteries
2-400 watt solar panels
3000 W inverter
MPPT 100/50 smartsolar charge controller

Which do you think is a better idea or are neither good? what advice do you offer? I have all the busbars, switches, fuses and correct wire gages.
options:

1) a stand alone charging station where the camper still has the normal 12 volt battery and the shore power cord is plugged into the above charge controller, this is the only connection between the camper and the above system. Kind of like plugging the camper into the house or RV park power except it will be the above system.

2) same above system, remove the normal 12 volt battery from the camper and turn off the camper internal converter. Connect the 4 batteries to the camper, use the shore power cord again from the camper and plug into the 3000 W inverter. Same as above except will be using the lithium batteries to run the 100v systems in the camper and the 12 volt systems such as lights etc.

 

[DutchmenSport]

Wow! That's way too complicated. But, I don't boondock either. I plug in the camper and forget it. Mine has 2 acid lead marine batteries. That's it. Simple.

 

[rvlifer]

Not enough info to say whether either or neither will work for you. Most solar setups i have seen use the 2nd. Seems like the 1st might be adding complexity that isnt needed by having multiole battery banks to maintain?

One battery bank where shorw power charges the batteries and solar charge controller does the same and the inverter powers everything form 1 bank is pretty simple and i believe what most do. Mine is set up that way and it has worked great.

Have you calculated all the power needs for what is in the rv and how you actually will use it to size your battery bank properly and is that enough solar to recharge the battery bank in a reasonable time?

Most people seem to go by what is on sale or or what others have done to guess what they need. Usually that ends up in a setup where they paid more than they needed to or it doesnt work quite as well as expected

 

[rvlifer]

Has the tech advanced to the point where you can draw ac power directly from a charge controller? You didnt list the exact equipment you plan to buy so couldnt look up your charge controller to check. Typically the charge controller charges the batteries at 12 v and you need the inverter to pull power out of the batteries and bump it to 120v to power ac circuits

Sooner later they will prob build the inverters into the charge controllers but havent seen that hapoen yet

 

[rvlifer]

I am assuming the inverter you are planning to buy also has a battery charger function. If it dont you wouldnt plug shore power into it.

 

[Gary RV_Wizard]

As RVlifer says, you only have #2 if the inverter is an inverter/charger. The inverter would be plugged into the RV 120v power system, which distributes power from the shore cord via the main breaker panel (load center).

I've not seen a solar charge controller that accepted 120vac input as well as solar panel DC, but that doesn't mean there is no such thing. But without that, there is no option #1.

Please describe your RV's existing shore power wiring and battery converter/charger. I think you may have a misconception about how 120v shore power feeds into the system.

 

[rvlifer]

I've not seen a solar charge controller that accepted 120vac input as well as solar panel DC, but that doesn't mean there is no such thing.

I have heard of systems that let you pull 120v directly off the solar panels but only a couple of times and i dont know what they used to accomplish that. All sounded really really expensive. Solar aint cheap to begin with lol

 

[Kevin Means]

Hi Sheldon, and welcome to the RVForum. Based solely on what you posted, I highly recommend keeping it simple. Run your solar panel's output to an MPPT controller, then fuse the controller's output at the battery bank. Don't mess with turning the converter (charger) on and off - it'll turn itself off when you're not plugged into shorepower. The outputs of the solar controller and the converter (charger) will play nice together when plugged into shorepower.

Once you start running solely off battery power and solar, I think you'll find that a good battery monitor will make off-grid camping a lot easier. You'll always know your battery's State Of Charge at a glance.

Kev

 

[Sheldon-M]

Thanks everyone for your input, appreciate it.
I have 4 100 amp hour lithium batteries
xwine 3000 W pure Sine wave inverter - input: DC 12 volt / output: AC 110 volt 60HZ
smartSolar charge controller MPPT 100/50 from Victron energy.
2 - 400 w solar panels

I am connecting the panels in series in order to keep the amps low and volts high. These will connect to the charge controller then to the batteries (connected in parallel to remain 12 volt then to a busbar.

From the bus bar to the invertor and this is where my question from above is. I only have one battery bank but will be coming off the busbar to just the invertor and go the route of option 1 or come of the busbar to the invertor and the camper like in option 2.

 

[Isaac-1]

What is the VOC of these panels, connecting all 4 in series may exceed the safe operating voltage of your MPPT charge controller, remember this is not simply adding up the VOC, but also calculating the cold weather voltage based on the coldest temperature the solar panels may be exposed to. Your MPPT allows for a max of 100 volts, this means you will likely be limited to around 80VOC total if the panels may ever see 10 degree F temperatures.

 

[Sheldon-M]

Thanks, I have 2 400 watt panels, not four. Temps will never reach 10 degree F, we are al closed up by the time those temps are here.
panel specs
VMP = 31.21V
IMP = 12.98A
VMP = 31.21 rounded to 31
IMP = 12.98A rounded to 13A
VOC = 37.23 V
LSC = 13.87 A

SERIES:
total output = 405W+405W = 810W
volts = 31+31 = 62V
Amps = 13
total output power = 806

 

[solarman]

Thanks, I have 2 400 watt panels, not four. Temps will never reach 10 degree F, we are al closed up by the time those temps are here.
panel specs
VMP = 31.21V
IMP = 12.98A
VMP = 31.21 rounded to 31
IMP = 12.98A rounded to 13A
VOC = 37.23 V
LSC = 13.87 A

SERIES:
total output = 405W+405W = 810W
volts = 31+31 = 62V
Amps = 13
total output power = 806

Never say never..

For controller spec, you should total the Voc not the Vmp
at Voc of 37.23*2 you have 74.45 Volts
at 32F you might get 85 Volts so you are ok with that controller.

one other point, you are over panneled for the controller.
the 100/50 can only handle 600 Watts into 12 Volts. ( 50 * 12 )
this is not such a bad thing, the controller will limit the wattage, but you can only harvest 600 Watts vs a theoretical 810 Watts.