Hi everyone! I'm from Germany, and I've noticed that our home AC circuits (230V) typically use 1-pole circuit breakers, which works fine for us. However, I've observed that solar circuits often utilize 2-pole circuit breakers. I understand that some benefits of 2-pole breakers include reducing the risk of arcing in DC circuits and protecting against reverse polarity in grounded AC systems. I'm curious, is redundancy another reason for their prevalence, and why are 2-pole breakers so commonly used in solar applications?
2 Answers
It's crucial to use a 2-pole breaker for DC systems because ground faults can happen on either pole, especially with modern transformerless inverters. Always go for a 2-pole isolator or breaker. Just keep in mind that PV arrays won’t trigger a breaker during a fault since they don't produce fault current—it's mainly for isolation.
There are a few reasons for this. First, your 230V AC system is grounded, so no need to disconnect the neutral. Conversely, some DC setups are ungrounded, meaning you need to break both poles to manage potential ground faults. Also, DC voltage is trickier because it doesn't have zero crossings, making it harder to break the circuit, especially at higher voltages like those in solar systems.
Absolutely, and it’s key for ensuring that the system is really isolated during maintenance!