Safety check for a first time build

[Pollack]

Hello!
Can you guys look at my chicken scratch plan and check if i made any mistakes.

Quick back story: I have a travel trailer that is currently equipped with one 100W unknown brand/specs solar panel, Renogy Wanderer 10a charge controller and two lead acid batteries that reached the end of their life span and no inverter.

With the new system I want to have enough power to be able to use a coffee maker, microwave, TV and other 110v electronics. Nothing big.

Here is my plan:
4x 100w Renogy solar panels (100w, ISC 5.21A)
1x Renogy Core mini 12.8V 300Ah Lithium Iron Phosphate Bettery
Renogy Rover Li 40Amp MPPT Charge Controller
Renogy PUH pure sine wave 3000W inverter.
Renogy Battery Shunt 300

I already have all the above so this part won't change.

My main question: is my cable/fuse choice safe/adequate
All cables are pure coper.
Busbars are 250amp
C1 - DC Miniature circuit breaker - Should I go with 20amp or is 10amp enough?
F1 - inline fuse 15A
F2 - Circuit breaker with manual reset - is 40amp good here or should I bump it up?
F3 - ANL fuse 250amp - or should go bigger?

Cables:
Battery->busbar->inverter 2/0cable
Solar->charge controller->busbar - 8AWG
Busbar-> trailer 12v fuse switch board - whatever is currently there
Inverter-> transfer switch - 10/2 W/G

And last question - should I keep the one existing solar panel and hook it up to the four I'm instaling? If so, how to connect it?

Thank you guys for all your help!!!!

EDIT:
I just noticed I made a mistake in the drawing. I drew the positive cable going into inverter being connected through on/off switch. I'm actually planning to connect that cable(with fuse) straight to the bus bar. On/Off switch will be only on the cable leading from the battery to the bus bar.

 

[JBertok]

Howdy,
Will start from the beginning:
F1 fuses: 8.13A is minimum, 10A is fine and their locations are good separating each string from each other.
C1 Double-Pole DC Breaker: 20A is fine. Depending on where this is located, it might be possible to omit the two F1s with individual PV shutdowns at the array. If you're wanting C1 indoors, it's fine.
MPPT PV Inputs: 8AWG is fine.
MPPT DC Output: consider upsizing to 6AWG; this MPPT does support 6AWG.
F2 fuse or circuit breaker: Consider upsizing to 50A considering the 80% rule with the 40A output maximum of the MPPT. (scattered clouds, cold temps, and sun at optimal angles can harvest greater than 100W from each panel.)
F3 fuses: Upsize to 400A; 250A is inadequate for a 3000W inverter.
Battery/inverter cabling: Consider upsizing to 4/0.
300A Shunt: fine.

Far as a transfer switch, I think this PUH version of their inverter has that built-in. Your AC wiring on both input and output from the inverter need to be 30A capable which is near the limit for staying cool using 10AWG. You could upsize that to 8AWG if possible and get 10A of safety margin.

There are some 10AWG at 12VDC coming off the bus bars for the existing trailer DC stuff. That needs a fuse or breaker since it's got full battery potential there.

For your existing 100W panel:
- if the panel is 12V nominal you can keep it with its current MPPT and fuse that to the DC bus. If the charger doesn't specifically support Lithium chemistry it might be fine to use it as long as you can ensure it doesn't try to equalize. Just watch the voltages as the battery tops out. If it trips the BMS then it won't work.
- if the panel is 24V nominal you can connect it to your 40A MPPT combiner. It may be necessary to put (a) blocking diode(s) inline with whichever has lower voltage - the strings or the single panel. To be clear - this is NOT an option if this is a 12V nominal panel; check rate label.

 

[Pollack]

Howdy,
Will start from the beginning:
F1 fuses: 8.13A is minimum, 10A is fine and their locations are good separating each string from each other.
C1 Double-Pole DC Breaker: 20A is fine. Depending on where this is located, it might be possible to omit the two F1s with individual PV shutdowns at the array. If you're wanting C1 indoors, it's fine.
MPPT PV Inputs: 8AWG is fine.
MPPT DC Output: consider upsizing to 6AWG; this MPPT does support 6AWG.
F2 fuse or circuit breaker: Consider upsizing to 50A considering the 80% rule with the 40A output maximum of the MPPT. (scattered clouds, cold temps, and sun at optimal angles can harvest greater than 100W from each panel.)
F3 fuses: Upsize to 400A; 250A is inadequate for a 3000W inverter.
Battery/inverter cabling: Consider upsizing to 4/0.
300A Shunt: fine.

Far as a transfer switch, I think this PUH version of their inverter has that built-in. Your AC wiring on both input and output from the inverter need to be 30A capable which is near the limit for staying cool using 10AWG. You could upsize that to 8AWG if possible and get 10A of safety margin.

There are some 10AWG at 12VDC coming off the bus bars for the existing trailer DC stuff. That needs a fuse or breaker since it's got full battery potential there.

For your existing 100W panel:
- if the panel is 12V nominal you can keep it with its current MPPT and fuse that to the DC bus. If the charger doesn't specifically support Lithium chemistry it might be fine to use it as long as you can ensure it doesn't try to equalize. Just watch the voltages as the battery tops out. If it trips the BMS then it won't work.
- if the panel is 24V nominal you can connect it to your 40A MPPT combiner. It may be necessary to put (a) blocking diode(s) inline with whichever has lower voltage - the strings or the single panel. To be clear - this is NOT an option if this is a 12V nominal panel; check rate label.

Thank you for your reply and input!

I'm going to do all the changes you suggested.

What size fuse/breaker should I use for the 12vDC coming of the bus bars to the existing trailer DC wiring.

I think I'm going to ditch the old 100W panel...I may use it later for a different project.

 

[robbob2112]

Near identical design - in a RV you probably don't need 240vac split-phase. I need to update the design to change out my fuses. The MRBF are now 250amp class T on each string. The class T between the second bus bar and the inverter is actually a 450amp version based on the inverter install manual.

Post in thread 'Robbob2112 Answer thread'

Oct 22, 2024

24volt UPS

Schneider Electric 865-2524 Conext SW 3,000 Watts, 24VDC Inverter/Charger for Split-phase 120/240 VAC

This inverter has been discontinued.

www.solar-electric.com

Schneider Electric RNW8651016 Conext SW DC Circuit Breaker Panel

Schneider Electric RNW8651016Conext SW DC Circuit Breaker Panel

www.solar-electric.com

Schneider Electric RNW8651017 Conext SW AC Circuit Breaker Panel for 120/240 VAC

Schneider Electric RNW8651017 Conext SW AC Circuit Breaker Panel for 120/240 VAC

www.solar-electric.com

Victron 250/100
4 - 335w Q cell panels.
Bus bars from Signature solar
Victron Smart Shunt
Class T fuse (150amp)
Class T fuse holder, ignition protected
Blue Sea systems switches for each battery bank
MRBF fuse + holder for each battery bank (also 150amp - each bank can run the inverter with the other off)
4 -...

• robbob2112

• 

Not quite finished with the install

Thread 'My build thread - robbob2112'

Nov 3, 2024

This is to document the prelimenary build

The basic design is here

This is just a temporary setup to power my office and a backup inverter that powers the office, server, bedrom, and den where the fish are. This will mean moving some wires from the main panel to a subpanel. I also need to run a 10/3 wire from the main panel to the basement where the inverter/batteries will be, then I have a 10/2 wire to run back up to the sub panel for the bedroom/livingroom breaker. I also have to run PV wires from...

• robbob2112

• 

 

[JBertok]

That will depend on the DC distribution panel and its needs, and the cabling feeding it.
Do a Google search on "DC Wire Size Chart" and reference your distance vs. amperage needs.
I couldn't say if 10AWG is appropriate for that, you'll have to dig into that distribution panel and see what's needed.

For fuses and breakers you only want to flow 80% of their rating through them at maximum possible "normal" load, and the wiring needs to be sized appropriate to that circuit protection device (which is larger) rather than the maximum possible load, to ensure everything is protected from a fault. Rule of thumb when distributing power into smaller branches is that you need another, smaller rated, protection device if the upstream protection from the current source is larger than the rating of the conductor you're stepping down to.