Volt and Amp - DC Circuit Breaker Question

In the following diagram I list the specs for the 24 panels I have.
My question is among the many different voltages listed and the various current specs listed, exactly which one would I use to calculate the total voltage and current for each of the two examples of wiring, on the left, a series wiring of all 12 panels in one circuit and the other wiring example on the right hand side being two paralleled 6 panel series wired circuit.
If someone can just type out the formula for each I would be grateful for that.
Thanks

12S is 12 * Voc and 1 * Isc
6S2P is 6 * Voc and 2 * Isc


Neither array configuration require over-current protection (OCP) because the panels themselves are the fuses. If your array is a single string or only 2P strings, you do not need it. For 3P or more, you need a fuse or breaker on each string.

In series, you add the voltage.
And the amperage stays the same.
In parallel, you add the amperage.
And the voltage stays the same.

sunshine_eggo said:

12S is 12 * Voc and 1 * Isc
6S2P is 6 * Voc and 2 * Isc


Neither array configuration require over-current protection (OCP) because the panels themselves are the fuses. If your array is a single string or only 2P strings, you do not need it. For 3P or more, you need a fuse or breaker on each string.

Click to expand...

Thanks for your response. I see there are two sets of electrical properties (STC) and (NOCT) and each has an Isc rating that is slightly different. For the purposes of making calculations for wire size for the 125 foot run from the Inverter to the panels - and for calculating ratings for breakers (or panel disconnect switches) which one of the ISC ratings should I use? (I would like to find a DC breaker that can perform the function of the disconnect switch if possible unless there is a good reason to not do that for some safety or engineering recommendation against doing so)

Thanks

You base limits and design on STC, i.e., calculations, wire selection, etc.

When it's actually up and running, you expect performance at or above NOCT most of the time. You will have times where it approaches STC and even exceeds STC in rare cases, but most of the time it will be in between the two ratings.

STC assumes cells are at 25°C. This only happens when it's cold outside because 80% of the energy hitting the panels is turned into heat. When it's cold outside, it's usually NOT summer, so the panels are not receiving optimal power.

On a 25°C day, the cells will be in the 40-50°C range due to heating, and this is usually listed for NOCT ratings. Hot cells operate at a lower voltage thus reducing power. Additionally, the NOCT rating assumes only 800W/m^2 is hitting the panel vs. the 1000W/m^2 for STC (20% less).

Using a DC breaker for a cut off switch is common practice.