Breakers or Fuses and Switches?

[BigSur]

I'm planning a simple system and would like advice/suggestions on breakers vs. fuses/switches:

The system:
- Single 100w poly panel
- 20a PWM SCC
- One 12v SLA 100 amp hr. battery
- 10agw wire
- Loads are LED lights and DC fans.

The problem:
I like the idea of in-line breakers so I can also easily switch off a component (like PV in to SCC) but having trouble finding ones with decent reviews. So far these look like the only/best options:

ZOOKOTO 20A Circuit Breaker Fuse Inverter with Manual Reset Button
T Tocas 32v DC Circuit Breaker Fuse Inverter with Manual Reset Button Switch Fuses 12V 20A

Questions:
- What fuses/breakers you are using and how you like them?
- Is it more practical and less hassle to use an in-line fuse and wire in a switch for manually cutting off instead of these breakers?

 

[chrisski]

My recommendation would be to skip the solar panel breaker. Don’t even need a fuse for just one panel.

If you do insist on one, look at Midnite SOlar. They have 150 VDC+ rated breakers that you can turn it on and off. Read the specs on the panel, so a 100 watt panel probably puts out 6 amps, so there’s some math involved, but it will work out to around 10 amps. Your 20 amp fuse Is probably good for two panels in parallel on your PWM controller. If you add more, you’ll need another breaker.

For the battery fuse, that really depends on your loads. I added three lights to my RV totaling .75 amps, and the fuse I added on that branch was 7.5 amps just because that’s the smallest I had and the wires in that are rated for more than 7.5 amps. FOr my main battery, I have a 2000 watt inverter, and I fused that at 200 amps. You definitely want a fuse from the battery.

 

[HateGrid]

Solar panels are current limiting, so you can short them out and nothing happens. Most panels can handle 20A through them and the MC4 connectors are typically rated for 30A. Once you parallel more than 3 panels, (like chrisski mentioned) then you need to look at fuses or breakers in your combiner box to prevent two panels from forcing more than the 20A limit through one panel with a short.

 

[Positronium]

If you do insist on one, look at Midnite SOlar. They have 150 VDC+ rated breakers that you can turn it on and off.

I primarily build portable 4s LiFePO4 projects usually with 60A BMS and 60A breaker. The breakers mentioned earlier are my go to. The picture attached is one of my projects with the MidNite Solar Unpolarized DC breaker. I like having the breakers act as on/off while also providing circuit protection. Small DC switches cannot handle 60A and in many of my projects, like the one in picture, I don't have the space for a Class T DC fuse, the fuse holder and a beefy DC switch. Below is the store I usually buy these breakers.

MidNite Solar MNEDC Circuit Breakers 150VDC

Shop now for MidNite Solar MNEDC Circuit Breakers 150VDC.

www.stellavolta.com

 

[chrisski]

I primarily build portable 4s LiFePO4 projects usually with 60A BMS and 60A breaker.

What is that tape you have over the terminals? I’ve seen it before, but I don’t know the name.

 

[Positronium]

What is that tape you have over the terminals? I’ve seen it before, but I don’t know the name.

That is Kapton tape.

 

[MrAubin]

Big Sur, I too would like to use those for solar disconnects before the charge controllers. Thier low profile unlike the monster height of conventional breakers.

 

[BigSur]

Big Sur, I too would like to use those for solar disconnects before the charge controllers. Thier low profile unlike the monster height of conventional breakers.

MrAubin, I’m sorry to say other priorities have taken me away from this project for a while and I haven’t moved forward. As a result I’ve made no decision yet.

Hopefully that’s about to change and I’ll get this project going again. I’m still eager to hear of others’ experiences. Thanks for resurrecting this thread!

 

[MrAubin]

Of coarse. I'm currently picking up spools of wire and other things to start making my first setup. Been planning 2 months now and have till this coming tax time to buy my 24 volt battery, and my 5 405 watt panels. I should have 4 more charge controllers and all my bus bars built by then. Only thing I haven't picked out due to lack of reviews is an inverter. Darnit, picture doesn't show the fuses on the battery terminal or the inverter terminal.

 

[DerpsyDoodler]

Of coarse. I'm currently picking up spools of wire and other things to start making my first setup. Been planning 2 months now and have till this coming tax time to buy my 24 volt battery, and my 5 405 watt panels. I should have 4 more charge controllers and all my bus bars built by then. Only thing I haven't picked out due to lack of reviews is an inverter. Darnit, picture doesn't show the fuses on the battery terminal or the inverter terminal.View attachment 59126

Why so many smaller charge controllers as opposed to say, 2x 40 amp and another 20, or 3x 40 amp?

 

[MrAubin]

Lots of reasons that are personal some make sense if you over think stuff some cause I'm dumb..... I don't like having a single issue that causes lots of problems like if a big controller goes down you have no panels. I can have them set to different angles per controller and better control my flow to my battery. Every controller has its own meter, I'll have multiple heat sensors on my one battery from each controller. Also, I love the look of neatly wired panels and breaker rooms having an array of charge controllers that look like my old Rockford fosgate car audio amps is super sexy. I have picture memory, but I can build in there too. I can see it all wired and installed already and I can't wait to do it and show everyone. I can afford to buy lots of smaller stuff periodically and it's easier to afford a 300 dollar controller than a 5 or 600 is alot harder to save for. Tax time will allot me around 6k that's when I'll order my battery and panels.