URGENT, HELP! 816W Solar Arrays, 60A MPPT Charge Controller, 12V 705AH Battery Bank

[solarsymplx]

Hello everyone! Please help. I am looking to complete a solar install in an RV for my parents by tomorrow!

The specs are as follows:

2 modules of 408 Watt Solar Arrays

60 Amp MPPT Charge Controller

12 V Battery Bank


From the panels to the charge controller, what kind of fuse should I have before my (+) line from the solar hits my charge controller? 75 AMP?

From the panels to the charge controller, what gauge wire should my (+) line be? 6 AWG?

From the charge controller to the battery bank, what gauge wire should my (+) be? Do the (+) and (-) wires need to be the same gauge?

From the battery bank, I have a Disconnect Switch, to a Fuse, to a Low Voltage Shutoff switch (RV does not have this built in), then it connects into the RV's 12V electrical system. Since I will be drawing power with a 316 Watt Refrigerator that's connected to the RV's 12V system, what gauge wire do I need through all of these components?

From the Disconnect Switch to the Low Voltage Shutoff, I have a fuse. What Amperage should it be?

Thank you for all of your help!

[solar pete]

Hello everyone! Please help. I am looking to complete a solar install in an RV for my parents by tomorrow!

The specs are as follows:

2 modules of 408 Watt Solar Arrays

60 Amp MPPT Charge Controller

12 V Battery Bank


From the panels to the charge controller, what kind of fuse should I have before my (+) line from the solar hits my charge controller? 75 AMP?

From the panels to the charge controller, what gauge wire should my (+) line be? 6 AWG?

From the charge controller to the battery bank, what gauge wire should my (+) be? Do the (+) and (-) wires need to be the same gauge?

From the battery bank, I have a Disconnect Switch, to a Fuse, to a Low Voltage Shutoff switch (RV does not have this built in), then it connects into the RV's 12V electrical system. Since I will be drawing power with a 316 Watt Refrigerator that's connected to the RV's 12V system, what gauge wire do I need through all of these components?

From the Disconnect Switch to the Low Voltage Shutoff, I have a fuse. What Amperage should it be?

Thank you for all of your help!

Howdy solarsymplex and welcome to solar panel talk. I am not a designer so I cant be of much help to you. Being that most of our experienced members are in the states and its Sunday you might not get any reply's till tomorrow.

I would suggest you start in the off grid section, for memory in one of those stickies there is a link to a site that has a type of calculator to help work out wire sizes, someone will be along at some stage to help you but I think you will be lucky to get it today, good luck with it, cheers.

[Bucho]

First of all tell us what solar panels you're using?

[Naptown]

Right off the bat that charge controller is too small for that amount of panel.
800w /12V= 66amps.
This is ok as long as the panels never reach near full output which likely if mounted flat on an RV.

[Naptown]

Full specs on the equipment used and distances between components.
If you are paralleling the collectors in 2 strings of 2 i series then no fuses are necessary betwen the collectors and charge controller. If 4 in parallel then fuses are required.
Is there an inverter involved and what wattage is that.
All connections to the battery should be fused. Blue sea makes some elegant fuse holders for this application.

[Sunking]

From the panels to the charge controller, what kind of fuse should I have before my (+) line from the solar hits my charge controller? 75 AMP?

Cannot be answered you have not provided any info. Panel specs and configuration are required. Most like no fuses required, depends on how it is cconfigured

From the panels to the charge controller, what gauge wire should my (+) line be? 6 AWG?

Cannot be answered, you have not provided any useful information.

From the charge controller to the battery bank, what gauge wire should my (+) be? Do the (+) and (-) wires need to be the same gauge?

That is a real scary question, indicates you know nothing about electricity. Minimum 6 AWG maybe, depends on length and YES they must be the same size.

[inetdog]

That is a real scary question, indicates you know nothing about electricity. Minimum 6 AWG maybe, depends on length and YES they must be the same size.

Yes and no. If you are talking about the minimum size, both wires must meet that.
If you are talking about voltage drop it does not make much sense to oversize one wire and not the other. The lowest voltage drop for the total amount of copper used will happen when both wires are the same size.

But if you make one wire more than large enough (say #4 if the calculations lead to that) and you have some #4 and some #2 wire left over from another project there is no harm in using the #2 for one of the wires.

PS: The important fact to keep in mind is that both wires will be carrying exactly the same current, so any decision you make about the size of one applies equaly well to the other.

[jflorey2]

From the battery bank, I have a Disconnect Switch, to a Fuse, to a Low Voltage Shutoff switch (RV does not have this built in), then it connects into the RV's 12V electrical system. Since I will be drawing power with a 316 Watt Refrigerator that's connected to the RV's 12V system, what gauge wire do I need through all of these components?
From the Disconnect Switch to the Low Voltage Shutoff, I have a fuse. What Amperage should it be?

A few issues here (plus all the other issues people have listed) -

A good DC breaker makes a lot more sense than a fuse+switch.
If you have an inverter that will likely be the largest transient load on the system. Size the fuse for that. It must pass full charge current of course.
60A of charge current is going to be a lot for most RV battery banks. C/4 or C/5 is a pretty fast rate for most lead-acids, so you'd want to make sure you have at least 300AH.
The fridge is probably a resistance heater + evap cycle type fridge, which is about the least efficient type of fridge there is.