MCB vs MCCB: Which one to use on your solar setup?

MCB means Miniature Circuit Breaker. It is mainly used for small-to-medium solar setups. MCCB means Molded Case Circuit Breaker. It is mainly used for medium-to-large setups.

You will notice on Shopee and Lazada that the maximum amperage for a standard MCB is typically 63A.

If you need a higher amperage, you will likely find a wider MCB that can support from 80A to 125A.

Since 125A is the maximum amperage it can handle, it means you are limited to the following setups based on your voltage:

Volts	Maximum Watts
12V	1,500W
24V	3,000W
48V	6,000W

This means a 12V setup using a 125A MCB has a maximum capacity of 1500W.

We also need to consider the 25% safety factor, which limits the usable power. This derates the available capacity of a 125A MCB, as shown in the updated table below:

Volts	Maximum Watts
12V	1,200W
24V	2,400W
48V	4,800W

Now, what if your 12V setup needs to handle a load exceeding 1200W? You have two options:

1. Convert your setup to 24V, which would allow you to handle up to 2400W.

2. Use MCCB that can handle higher amperes.

MCCB sizes available online typically range from 100A to 250A.

This means a 250A MCCB will have the following capacity after applying the safety factor (25%):

Volts	Maximum Watts
12V	2,400W
24V	4,800W
48V	9,600W

So choosing between MCB and MCCB is now easier. Here's the summary for you:

Breaker	Amperes	Usable Watts	Buy
MCB	63A	605W
Wider MCB	125A	1,200W
MCCB	250A	2,400W

Breaker	Amperes	Usable Watts	Buy
MCB	63A	1,210W
Wider MCB	125A	2,400W
MCCB	250A	4,800W

Breaker	Amperes	Usable Watts	Buy
MCB	63A	2,420W
Wider MCB	125A	4,800W
MCCB	250A	9,600W

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