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[1l243]

Hello I am new to the forum and new to solar. I am so new my system has been ordered but has not arrived yet. I am doing research in preparation for the arrival of all the components.

My system is for my 36 foot Toy Hauler TT. I ordered a 500 watt kit that comes with 5/100 watt panels and a 40amp PWM Charge/Controller. I also ordered a Renogy 2000w inverter... I have a 340ah lead acid battery bank

My plan is to mount the panels on the roof and to wire the panels in parallel. Access the inside the trailer via the fridge roof vent. Install the charger controller in the trailer for easy viewing and then connect to the batteries of the trailer. I will mount the inverter in the storage compartment about 4 feet from the batteries. I plan to use a disconnect switch between the charger controller and the panels. A 50 amp breaker between the battery and the charger controller and a fuse or breaker between the battery and inverter.

What I have since learned of what I don't know?

1. The distance between where I was going to mount the charge controller and the batteries is 20 feet. I have read that this distance is not acceptable due to volt drop? Is it correct that I have to mount the charge controller as close to the batteries as possible? The problem is that the charge controller would not be easily visible for viewing status at this location. However the controller is supposed to have a smart phone app that I may be able to use.

2. Is there a difference between using a fuse vs a breaker? What size fuse/breaker should I use between the battery and the 2000w inverter?

3. If my charge controller is going to be out of view I plan on getting a remote battery monitor. With keeping the price down in mind I like this unit for the display features.

https://www.amazon.com/AiLi-Program...ry+monitor&qid=1611648492&sr=8-13&tag=mh0b-20

Everything but the battery monitor on it's way and can't be changed at this point.

Any help or advise is appreciated.

 

[Dzl]

Hello I am new to the forum and new to solar.

Welcome to the forum!

1. The distance between where I was going to mount the charge controller and the batteries is 20 feet. I have read that this distance is not acceptable due to volt drop? Is it correct that I have to mount the charge controller as close to the batteries as possible? The problem is that the charge controller would not be easily visible for viewing status at this location. However the controller is supposed to have a smart phone app that I may be able to use.

Voltage drop is just a math problem. If its too high, any one of these three options can reduce Vdrop:
1. Use larger wire
2. Reduce the current
3. Reduce the distance

2. Is there a difference between using a fuse vs a breaker? What size fuse/breaker should I use between the battery and the 2000w inverter?

Best bet is to consult your inverter manual and follow their guidance.

At a minimum, I would use math similar to this:
2000W / inverter low voltage disconnect voltage / efficiency = amps x 1.25 = approximate minimum fuse/breaker current rating (and wire would need to be larger than this number)

For instance:
2000W / 10.5V / 0.85 efficiency = 225 x 1.25 = 280A

 

[Whinny]

Where is your converter in relation to the preferred solar controller location? It may have two #4 wires feeding it, they may be enough. The controller could be hooked up like any other 12v device through an empty existing fuse location in the converter. Try it, even temporary, and measure the voltage drop if its fine you are good to go.

 

[1l243]

Thanks for the info. When my components come in and after I get the panels installed I could temporarily connect the charge controller add 5 feet of cable going out and measure voltage then add 20 feet of cable and measure again and see what the voltage drop is. Then determine what volt drop is acceptable?

The math problem should also include the cost of running large diameter wire long distances.

I purchased extra 10ga solar cable for this purpose but it may not be large enough.

The converter is located in a wall partisan between the living space and front bedroom. To access I would have to enter the trailer though the fridge vent through the floor and then back through the floor and up into the wall partisan. Or access from the roof into the wall partisan and hope my aim is good.

 

[Whinny]

I tried to edit my earlier post-but couldn't find it.
I wasn't thinking about 500 watts when I suggested the converter, you have too much panel to hook to a existing fuse holder. It probably needs a fuse or breaker for 50-60 amps. If the converter is difficult to get to probably easier to go to the battery buss bar. When you go in the fridge vent stay to the cold side, opposite the burner tube and be sure to seal cable entrance to the coach side-carbon monoxide is the concern.

 

[1l243]

I found a Voltage Drop Calculator on the Interweb. If it's accurate and the perimeters I am putting in are correct it's very helpful.

Perimeters

Voltage 14.3 volts
Phase Single
Ampres 40amp
Wire size 10awg
Conductor Copper
Distance 25 feet

10ga wire at 25 feet is voltage drop is 2.49 volts to 11.81 volts at 17.41% drop
8ga wire at 25 feet voltage drop is 1.56 vots to 12.74 volts at 10.91% drop
6ga wire at 25 feet voltage drop is .98 volts to 13.32 volts at 6.85% drop
4ga wire at 25 feet voltage drop is .62 volts to 13.68 volts at 4.34% drop.

I think this tells me all I need to know.

I am thinking I could get by with 6ga wire spanning 25 feet from charge controller to battery?

There is no significant drop at 5 feet using 10 ga wire...

 

[Forbisher]

I found a Voltage Drop Calculator on the Interweb. If it's accurate and the perimeters I am putting in are correct it's very helpful.

Perimeters

Voltage 14.3 volts
Phase Single
Ampres 40amp
Wire size 10awg
Conductor Copper
Distance 25 feet

10ga wire at 25 feet is voltage drop is 2.49 volts to 11.81 volts at 17.41% drop
8ga wire at 25 feet voltage drop is 1.56 vots to 12.74 volts at 10.91% drop
6ga wire at 25 feet voltage drop is .98 volts to 13.32 volts at 6.85% drop
4ga wire at 25 feet voltage drop is .62 volts to 13.68 volts at 4.34% drop.

I think this tells me all I need to know.

I am thinking I could get by with 6ga wire spanning 25 feet from charge controller to battery?

There is no significant drop at 5 feet using 10 ga wire...

5.5A 100w panels in parallel x 5 is about 28A and 18Vmp.

Unfortunately you bought a PWM instead of MPPT but 5 panels would have had to be in parallel too on a MPPT.
6 panels would have been a better choice or larger than 100w panels.
3S2P
2S3P
Click the calculator link.
6 AWG is about 3% drop for your system.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[1l243]

5.5A 100w panels in parallel x 5 is about 28A and 18Vmp.

Unfortunately you bought a PWM instead of MPPT but 5 panels would have had to be in parallel too on a MPPT.
6 panels would have been a better choice or larger than 100w panels.
3S2P
2S3P
Click the calculator link.
6 AWG is about 3% drop for your system.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Hi Forbisher. were you measuring volt drop from panel to charge controller? I was measuring the voltage drop from the charge controller to the battery. According to specs 14.3 volts is coming out of the charge controller to the battery.
Thanks

 

[Forbisher]

Hi Forbisher. were you measuring volt drop from panel to charge controller? I was measuring the voltage drop from the charge controller to the battery. According to specs 14.3 volts is coming out of the charge controller to the battery.
Thanks

Yes panels to SCC as I got fixated on your poor choice of a PWM controller.
From your new post asking basically the same question 35 feet 10 AWG is 10.88% volt drop which is not good.
You needed 6 AWG at 25 feet to be at 3%.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net