Help and Clarification on Trailer Solar Install

oldjohnt · March 9, 2021

Good Morning Ken, a bright new sunny day here in Florida with a bit more time on my hands… GREAT info from Chad hope he had a good anniversary and then apparently had the time to answer your questions in more detail (he even sized your cables, how generous, you owe him a steak dinner lol) then I did yesterday MY BAD. Looks like we pretty well agree especially with respect to where to locate overcurrent protection,,,,,,,,,preference for a battery monitor,,,,,,,,,,,use of a master battery disconnect,,,,,,,,,,,,,,,,Fuse choice,,,,,,,,,,,,Blue Sea Products. Might it be said "Great minds think alike" orrrrrrrrrr "Even a blind squirrel finds a nut now n then" lol

For your convenience here is a bit more info and sources that may help you.

Wire Ampacity Chart

Ampacity Charts - Cerrowire

PS the ampacity of single conductors IN FREE AIR is much much higher then if its jacketed,,,,,,,,,Type and class of insulation,,,,,,,,,,, or enclosed in conduit,,,,,,, and if so how many of what ampacity in what size conduit,,,,,,,,,Its not as easy as some think and often for RV use its a conductor in free air which is far greater then in in conduit due to the ability to dissipate heat to the environment. Similar if a person has say a 2000 Watt Inverter it may be seldom its ever fully loaded same as a rooftop panel will likely never or seldom produce it rating. I still design for the worst case and assume the max currents when sizing conductors.

Voltage Drop Calculator, easy to use simply plug in the distance current and wire size

Voltage Drop Calculator

Class T versus ANL fuses in RV Applications. ANL have less current interrupting capacity then T. With your three 100 AH AGM’s, I FWIW agree with Chad to choose the higher rated fuse just to be on the safe side. If a few more bucks might prevent a fire I know what I would use

Class T vs ANL fuse | DIY Solar Power Forum (diysolarforum.com)

Blue Sea Systems

Blue Sea Systems - Innovative Electrical Systems — Built to last

IMPORTANT

When it comes to connecting multiple batteries in parallel, here’s something I found to be very important which most people aren’t even aware of, which helps insure ALL batteries receive the same load and charging balance. I highly recommend you take a look and connect your batteries accordingly so EACH charges and supplies equal current VERY IMPORTANT IN MY OPINION

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

NOTE hopefully your Inverter is already designed and configured (likely so) such that in your entire AC Distribution THERE IS ONLYYYYYYYY ONE NEUTRAL GROUND BOND. Remember your AC panel has isolated and insulated Neutral and Ground Busses so the one AND ONLY NG Bond (NOT two) occurs prior to reaching there. Were you to use a portable genset and your transfer scheme bonded the two Neutrals (IE NO Neutral switching) the genset needs to have a FLOATING NEUTRAL. Some come from the factory floating others bonded for very good reasons. This is especially important if an EMS is used as it will go bonkers if this is incorrect lol

PS In cases where the frame ground of an RV is used to carry NEG return current I recommend the frame Grounding cables be as large as the + conductors, however if simply used for reference grounding (NOT carrying high current) purposes, many RV, Automotive, Manufacturer, and even NEC if and where applicable (sure not much if any) allow smaller cable, although sure it never hurts if bigger… OF COURSE do as the manufacturer suggests as a minimum and even larger if you like. Me being an old very conservative designer all my life go over engineered lol and use bigger cables even if a tad more expensive YOUR CALL...........

Nuff said for now. If you work through both our latest responses, I think you have all the tools resources and answers you need. Sorry I didn’t have time to go deep in the weeds with more detail but it was still fun helping you..

HATS OFF TO CHAD for all the time effort and detail he provides. Heck next time I will just use him to save myself a ton of work lol wink wink

KEEP US POSTED and if you have any more questions let us know

God Bless

John T NOT any Solar Expert, I come more from the Power Distribution side of the aisle...

Edited March 9, 2021 by oldjohnt

Ken Larson · March 9, 2021

Guys, Thank You, Thank You.

Chad, I'll replace the 6AWG to chassis ground with 2 AWG as you suggest. So, I think I am ready to go; just waiting for the panels to arrive and for the weather to warm up a little.

Chad Heiser · March 9, 2021

5 hours ago, Ken Larson said:

Guys, Thank You, Thank You.

Chad, I'll replace the 6AWG to chassis ground with 2 AWG as you suggest. So, I think I am ready to go; just waiting for the panels to arrive and for the weather to warm up a little.

Did you mean 2/0 rather than 2 AWG. I never mentioned 2 AWG. The battery ground should be the same size as the battery cables - 2/0.

Ken Larson · March 10, 2021

typos happen

Chad Heiser · March 10, 2021

1 hour ago, Ken Larson said:

typos happen

I figured as much, but just wanted to make sure. 👍

oldjohnt · March 10, 2021

Ken, what would help now is if you post a detailed updated schematic of your proposed system that includes all our upgrades and suggestions above... Just sayin

John T