Help Identifying/Understanding Fault Protection and Where

[myersfamilyhome]

Can someone help me understand how to determine if a fuse/breaker is needed for 1-9, how to determine the size of the fuse/breaker, and if possible explain why at that location

Understandings (please correct me if I'm wrong):
* DC (Direct Current) power flows in a loop.
* Because DC requires a loop (complete circuit) to function, there must be a common positive and negative connection to complete the flow of electrons.
* When power is being generated by DC equipment the flow of power is pushed out the positive line and returns (completes the loop) through the negative line.
* When power is being consumed by DC equipment the power is pulled in through the positive line and returns (completes the loop) through the negative line.
* Using river analogy, voltage is speed of river flow, current/amps is the width of river, and resistance is riverbed water is in contact with. With this in mind the length of a river(wire), will lose speed of water flow(voltage drop) simply due to resistance, and the width of river (wire size) determines the amount of water (amperage) at any point in the river that can pass through. If the river isn't wide enough (wire gauge) and the amount of water (amps) is greater than capacity, the water will overflow creating resistance/friction (heat).
* A Series Connection (connecting negative of one power source to the positive of another like power source). This adds the amperage output of all in series while maintaining the lowest voltage produced from the series.
* A Parallel Connection (connecting positive power lines together and negative power lines together of common power sources). This adds the voltage output of all in parallel while maintaining the lowest amperage produced from parallel.
* Parallel and Series and be combined to get wanted output as long as wire can handle current (amps) and have common voltage.
* Breakers/Fuses are used only on positive lines. This allows the fuse/breaker to protect the wire/circuit/equipment that a fault/surge could damage before it gets that far.

Basic Solar Model:
Sun ? - (lol had to add this)
PV - (Solar Panels)
PV Series Wiring - (PV- to PV+)
[1. Fuse/Breaker(s)? - Between Panels]
PV Parallel Wiring - (PV+/- to Combiner)
[2. Fuse/Breaker(s)? - Leaving Panels]
Combiner - (1,2,3,4to1 or Combiner Box)
[3. Fuse/Breaker(s)? - Leaving Combiner]
Charge Controller (Convert PV Power to Common Battery Voltage Power)
[4. Fuse/Breaker(s)? - Leaving Charge Controller]
Bus Bar - (+Distribution of CC Power)
[5. Fuse/Breaker(s)? - Leaving Bus Bar to Inverter]
[6. Fuse/Breaker(s)? - Leaving Bus Bar to Converter]
Converter - (Converts CC/Battery Power to Different DC Power)
[7. Fuse/Breaker(s)? - Leaving Converter to Circuits]
[8. Fuse/Breaker(s)? - Leaving Bus Bar to BMS]
BMS - (Manages Battery Bank)
[9. Fuse/Breaker(s)? - Leaving BMS to Each Battery/Cell]

Thanks to everyone for help

 

[12VoltInstalls]

power is pulled in through the positive line and returns (completes the loop) through the negative line.

backwards

 

[myersfamilyhome]

backwards

So the device consuming power is pulling it in through it's negative (- / most cases black) connection? I always thought the black was ground and was not the supply line.

 

[Zil]

It makes 'no never mind' what direction the electrons may move through a wire. At one time the negative was configured as hot. We now customarily use the positive side of DC as the hot side and the negative side as the "return". Most of the devices we use are designed with that specification and their cases are polarized as negative. Unfortunately there are exceptions with some imported devices. As a standard vehicle has it's chassis polarized as negative, these few devices must be isolated from the chassis.
Because of our specification of positive dc as hot side we fuse the positive side and we call that 'feed'.
Some devices have internal fuses or the manufacturer specifies a certain ampere fuse. But the wire to that fuse must be protected with a fuse sized to the ampacity of that wire. The locations of fuses and the size of fuses are well engineered and that information is readily available on the internet and some very well presented manuals. Be careful of information found on the internet, especially on various forums. some information is from experts, some seems just made up on the spot..
The BMS that I have seen are on the negative side and therefore not fused.
When connecting batteries in series, negative to positive, the voltage increases by adding each battery voltage. The amp/hour stays the same.
When connecting in parallel, positive to positive, negative to negative, the voltage stays the same but the amp/hour adds up.
Yes batteries and solar panels can be configured to any voltage and ampere by combination of series and parallel.

 

[12VoltInstalls]

So the device consuming power is pulling it in through it's negative (- / most cases black) connection? I always thought the black was ground and was not the supply line.

Don’t think of it as “pulling”

The “+” IS ‘the supply line’ but the electrons move the opposite direction of what most people think.
The electrons are ‘freed’ or ‘captured’ by a chemical action when an opposing potential (sortofa controlled short in discharge, or the battery is the controlled short when charging) is applied to the electrodes at the opposite ends of the electrolyte solution.

I maybe shouldn’t have brought any of that up. It doesn’t change what we do with solar.

 

[myersfamilyhome]

Don’t think of it as “pulling”

The “+” IS ‘the supply line’ but the electrons move the opposite direction of what most people think.
The electrons are ‘freed’ or ‘captured’ by a chemical action when an opposing potential (sortofa controlled short in discharge, or the battery is the controlled short when charging) is applied to the electrodes at the opposite ends of the electrolyte solution.

I maybe shouldn’t have brought any of that up. It doesn’t change what we do with solar.

I really appreciate the technical details. The more it makes sense and can help bridge gaps of understanding the better down the road when it's needed. It also helps me direct my drive to learn more. Found a great explanation that helped me better understand more about batteries, electrons, and flow.

How a battery works

How do batteries power our phones, computers and other devices?

www.science.org.au

Guess we got a little off track from my original question, but always good to learn more ?. Now if I can just get input on how to protect my system so I can get things ordered lol.

 

[Zil]

Size fuses to protect the ampacity of the cable & wire.
Put a Fuse close to the power source. Have a catastrophic fuse located as close to the battery as possible.
I fuse the battery positive going to the Positive BusBar. I fuse the circuits leaving the BusBar at the BusBar. Inverter, Charge source, and branch fuse block.
Note the charge sources are fused at the battery or BusBar positive end, not the charger end of the cable.