Quick question for a newbie... Concerning 400watt system in book.

Mirro108

New Member
Hey everyone,
First off i am modeling my system off of the 400 watt 12v system except im using 1 x 300 watt panel instead on 4 x100 watt panels. But otherwise im running 40 amp mppt charge controller, 100 ah lithium iron phosphate battery, 1200 watt inverter, and the blue sea fuse block.
Which is where my question comes in.
In this system should there be another fuse involved between the 100-200 amp fuse (mine is 175 amp) off the main before the inverter and the blue sea fuse block? The fuse block says max input should be 125 amps. So shouldn't there be another 120-125amp fuse before the 12 v fuse block? If not can someone explain.
 

svetz

Works in theory! Practice? That's something else
Staff member
Moderator
Fuses (or circuit breakers) protect the wires. Every wire (aka circuit) should have a fuse somewhere in the circuit and the fuse sized for the smallest gauge in the circuit. Both the AC and DC side need them.
Some folks also use breakers as "disconnects" to make working on parts of the system easier to de-energize (e.g., between the panels and the MPPT).
 

Zil

Solar Addict
What I have. 690ah battery positive > fuse> cable >buss bar> fuse #1 to inverter; fuse #2 for charge controller; fuse #3 for Blue Sea fuse block.
 

MisterSandals

Participation Medalist
The fuse block says max input should be 125 amps. So shouldn't there be another 120-125amp fuse before the 12 v fuse block?
It sounds like your fuse block is undersized. You are correct in thinking there should be protection before the fuse block if there is a potential to pull more amps than it is rated for.

But mostly bad design with that fuse block.
 

Mirro108

New Member
Ok i used the design and parts suggested from the website and book. Except the panel. The design is straight from the book and website.. If there is a specific fuse block # it isn't stated.

I am just trying to make sure i dont fry my fuse block and electronics after the block..

Because i noticed the parts suggested didn't have a fuse between and it is only a 125amp max input as stated by the manufacturers.
 

Mirro108

New Member
It sounds like your fuse block is undersized. You are correct in thinking there should be protection before the fuse block if there is a potential to pull more amps than it is rated for.

But mostly bad design with that fuse block.
I will personally never pull more. But there is potential for someone to do so, so i was just making certain for people who may not notice this.
My whole system will be dc and very minimal power useage.. Ie laptop, cell phone, 2x small fans, and 5 x 15watt cod leds. Nothing large draw.
 

vansvan

New Member
@Mirro108 I am working through the same issue. I am using a 1000w inverter with the same fuse box you have. I am supposed to use a 150A fuse, but I also noticed the fuse box had a max of 125A. Did you end up using the 175A fuse between the fuse box and battery? Also super new to the solar game
 
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