Advice on RV Set up & Wiring?

[Carv]

Thanks for the answers Mike, some make it clearer some make it muddier

That is a good question on how many panel watts I'll need. Since higher panel watts equal higher controller volts I assume I'll be limited at a certain point by finances and what I can pick up used. I'm thinking I'll probably max out around 60A MPPT based on price which would limit me to 720W or less. Since I'm approaching this from the reverse I think I'd be better off figuring out how many watts the various panel(s) will make based on their rating and figure out what is a sufficient amount to run my set up or at least get close without over taxing the battery charge amps and frying them or decreasing their life span prematurely.

Is there an equation for actual panel wattage production based on rated watts? I can also make my panel(s) tilt if need be and I can position my trailer for max sun when I initially park it plus I'm in the southern CA desert not far from Mexico & Arizona so there is lots of intense sun exposure.


I do have some further questions to help clarify things based on your answers:

Design Questions:
1) watts are watts, as long as you stay under the kill voltage of your controller. Volts "transport" easier, thin wire, Amps need thick expensive wire
Q) Since I'm in the 12V box I assume I'll need thicker wire due to higher amps but that thicker wire is from the controller to the batteries or positive distribution block NOT from the panels, to the solar charge controller correct?

2) Better controllers do allow a programmable Max Amps to lessen BBQ'ing your batteries.
Q) Does a Morningstar MPPT TS have this feature? also what are some other recommended MPPT controllers in the 30A to 60A range?

3) How much concurrent load will the system see? if you divert charging amps from the batteries to the inverter to power the fridge, the batteries take longer to charge.
Q-1) The fridge is rated at 1.1A AC not sure what the inverter will pull DC to make 1.1A AC? Either way it's coming form the charge controller and since the batteries have inefficiencies in them hence your 80% conversion for new batteries, wouldn't it be better to run the inverter directly off the charge controller while the current is there and then off the batteries when it's not? But since there is no way to switch between the two & there would be draw for both the batteries & the inverter I guess the question you're getting at is; if there is enough DC AMPs to charge the batteries AND run the fridge at the same time, with a 1.1A AC rating can I assume it'd take very little DC Amps to run the fridge??? Is there a conversion equation for this?
Q-2) What happens to the incoming DC from the charge controller once the batteries are full?

4) MPPT controllers Must remain powered by a battery whenever the solar input is connected.
Q) Do most MPPT controllers have a "Disconnect" for the Solar input line that kills any current coming from the panels? If so, there'd be current in the solar input line but it's just disconnected between the panel(s) and the charge controller and I could remove the batteries with no worry about any discharge or live line issues while the trailer is not in use?


Wiring Questions:

1) The 200A breaker at the battery protects the 200A wire (1/O) you have running to the + Bus. Each wire coming off the + Bus, needs to have it's own protection, 10ga wire needs 30A
Q-1) Can I just skip the 200A at the battery and fuse each component (inverter & controller) instead?
Q-2) what type of fuse is recommended a shunt an actual fuse, a reset-able breaker??

2) You can use a common - terminal, don't expect to carry any amps through the trailer frame, some joints are painted and bolted, some have rubber damping material.....
Q) My frame is all welded, BUT I'm not looking to carry any current through the frame I only want to avoid having to make multiple runs back to the negative battery terminal through the floor if it can be grounded to the frame locally. After all the batteries are grounded to the frame with the same set up (I welded a bolt to the frame at the battery tray).

3) inverter grounding. Follow the rules that come with the inverter. Consider the chassis bolt to be the ground rod, since mobile trailers aren't required to be wired to a ground rod.
Q) I spoke to a C.S. rep at go power and they confirmed that if I run it chassis grounded to the negative terminal It creates a ground loop and trips the AC GFCI on the inverter. Not concerned with what is required as that changes depending on who you talk to and their knowledge and level of understanding of the system structure, I just want it to work correctly with no danger of causing issues.


Thanks

[Mike90250]

Welcome,
Well you are asking good questions. here are some possible answers,

The question you DIDN'T ask, is how much PV will I need to power my gear to keep my batteries healthy ?
Get a "Kill-a-watt" meter and measure your fridge for a week of use at home, and figure your daily KWh usage.
I expect you will require 1KWh daily just for the fridge, and more for lighting, fan, laptop, phone.....
Can 400W of PV harvest 200% of your daily load ? Only expect 4 solar hours winter, 5 or 6 in summer, even in the desert

Design Questions:
1) watts are watts, as long as you stay under the kill voltage of your controller.
Volts "transport" easier, thin wire, Amps need thick expensive wire

2) Better controllers do allow a programmable Max Amps to lessen BBQ'ing your batteries.

3) How much concurrent load will the system see? if you divert charging amps from the
batteries to the inverter to power the fridge, the batteries take longer to charge.
With new batteries, expect 20A out, to be replenished with 24A back in. (80% efficient) Older batteries are less efficient.
With a MPPT controller, expect 95% of the watts IN to come out for loads & charging

4) MPPT controllers Must remain powered by a battery whenever the solar input is connected. The stable battery voltage is where the Brains (CPU) is powered from. Always connect to battery first, wait for it to boot, then connect solar. Reverse sequence for power down, or you get to buy a new controller.


Wiring Questions:

1) The 200A breaker at the battery protects the 200A wire (4/O) you have running to the + Bus.
Each wire coming off the + Bus, needs to have it's own protection, 10ga wire needs 30A
12ga wire needs 20A, use the NEC gauge/amps chart to select the protection for each wire.
(google "NEC AWG wire ampacity", the first 3 results are pretty good)
Large wire sizes 2/O, 4/O use the capital o, not zero O 0
Any wire larger than #8ga requires a 6-12 ton hydraulic crimp tool to make a secure, safe connection,
or purchase pre-terminated wires. The cheap hammer type crimp tool does not always make a secure
connection.
It's always safe to use a larger wire, on a small fuse, than a small wire on a large fuse.
(think burning insulation and white hot wire)

2) You can use a common - terminal, don't expect to carry any amps through the trailer frame, some joints are painted and bolted, some have rubber damping material.....

3) inverter grounding. Follow the rules that come with the inverter. Consider the chassis bolt to be the ground rod, since mobile trailers aren't required to be wired to a ground rod. (picture a campground where folks for a season, leave ground rods behind)

[Carv]

I'll start out by saying I'm a bit of a noob to solar, I have some experience with electrical, I'm fairly handy, and I'm in the process of learning how to design & set up the system I'm looking for and could use some advice on how to make what I want to do work properly.


I have an enclosed trailer that I use for trips to the CA desert, the trips are usually 3 days but can be up to 5 days on occasion and I'm in the process of gathering & installing the equipment I'll need for my solar system and I'm looking for advice on design, equipment, & how to wire it 8/10 times I have full sun.


My goal is to run my mini fridge (converted mini vertical freezer) off of the batteries through a pure sign wave inverter without draining the batteries or running it off of my generator while I'm on my trips. (I went with a mini fridge & solar over propane due to the cost of a used propane fridge alone being $500+, the propane fridge size being too large to fit under my work bench, having to mount and plumb propane lines which my trailer does not currently have, and I like having 2 charged 6Vs to run my 12V LED lights in the trailer, so before you say just get a propane fridge I've weighed my options and this is how I've decided to go as it fits my needs and I can build the whole solar system for the cost of a used propane fridge alone).

I currently have:
-2 -6Vs mounted on the trailer tongue wired in series (there is not room for 4 -6V with the current battery tray configuration and it is not worth altering it to me, I'm in the 12V box)
-Mini Fridge rated at 1.1A or about 120W, which is a converted vertical mini freezer that probably runs 3 out of every 15-20 minutes for cycle run time.
-1500W Go Power Pure Sine wave inverter, Note, I'm ONLY using this to run the fridge and been told by Go Power that it only pulls the DC load required to power what ever is pulled on the AC side which is 120W, so not in fire danger.
-I've ran 1/0 on the battery set up and 10 foot positive power lead into the trailer where I'm mounting the Inverter & solar charger
Note: I've also made a test run with these batteries, this inverter, & this fridge and it went 72 hours and drained the batteries to 11.8V and this is why I need solar to keep the batteries charged, the fridge working and the lights on so charging and running off batteries only is not an option.

I Currently Need to get:
-Solar panel or panels
-MPPT charge controller


Design Questions:
I plan on getting one 315 or 335W panel (or I can get two 200-225W panels) BUT I prefer a single panel for mounting space reasons.

Q-1) Is there any difference between running one panel or two panels? I understand wattage differences but is there an advantage or dis-advantage to running one VS two panels?

Q-2) If I go with a single 315W 60 or 72 cell panel I can do a 30A MPPT controller, if the price is negligible does it matter with my current system design if I go with a larger controller say a 60A or an 80A so I have extra controller capability if I want more panels in the future can the controller be turned down or it can not be turned down and will this fry my current batteries becuase too many Amps being fed in to the system?

Q-3) With my current set up and a 30A or 40A controller how fast will the batteries charge (assuming average desert sun) and what happens to the incoming electricity once the batteries are full?

Q-4) If I remove the 2 -6V batteries from the system and the inverter is turned off, what happens to the incoming electricity from the MPPT controller, the DC line is still live or can I turn the controller off and what the panels are producing just gets eaten by the charge controller?


Wiring Questions:
I have made a diagram of how I think I'd like to run the wiring but I do have a few questions to make sure I'm not creating any issues or dangers (see attached diagram).
Q-1) Instead of making runs to the battery terminals for the inverter & solar charge controller can I just install a distribution block locally where the equipment is mounted and tie them all together there instead of at the battery terminals on the positive side?

Q-2) On the negative side, I have welded a bolt to the frame locally where the inverter & charge controller will be mounted on the inside of the trailer can I run both negative leads to this bolt and mount them together instead of making runs back to the negative battery terminals?

Q-3) The inverter has a chassis ground that is grounded to the GCFI plug on it, if I connect the chassis ground to the same terminal as the DC negative lead I believe it will create a ground loop and trip the GCFI, is this correct? If so I need to just leave the chassis ground NOT connected/grounded, correct?