First System Build Thread - Another 71kwh DIY

[Brucey]

Very cool setup. I guess my only question is if an mrbf fuse can handle the DC arc from a big battery like that. Most here seem to be using class t, or quality DC breakers, for large batteries in parallel.

 

[Disturbedfuel15]

Very cool setup. I guess my only question is if an mrbf fuse can handle the DC arc from a big battery like that. Most here seem to be using class t, or quality DC breakers, for large batteries in parallel.

Thanks. I must be naive if you wouldn't mind explaining? I have five south bend 58v 150a mrbf, one on each battery (I'm sure you saw that, I'm just repeating for clarity). They weren't terribly expensive, so if I need to change them for safety reasons, I will. I did not choose these based on price, I chose them based on safety, I thought

 

[Brucey]

Thanks. I must be naive if you wouldn't mind explaining? I have five south bend 58v 150a mrbf, one on each battery (I'm sure you saw that, I'm just repeating for clarity). They weren't terribly expensive, so if I need to change them for safety reasons, I will. I did not choose these based on price, I chose them based on safety, I thought

If those were mine, for each battery, I would use a midnite solar MNEDC250 DC breaker, then connect to the bus bar. They are pretty large so I don't think they will fit in your current enclosure. That will act as a backup in case the mrbf fails to open. The mrbf is a solid choice but we've seen instances where they fail quite spectacularly under the high current that LFP batteries can deliver.

@SilverbackMP uses a midnite 2000A battery combiner box, which has room for 12 of them, for his large parallel banks, he also has a class T and an EV shunt for each within the battery enclosures so a lot of redundancy in that design.

My more modest configuration, work in progress, mnedc250s connected to a power in:

 

[Disturbedfuel15]

Thanks for posting your configuration. This is good knowledge. I will say that I use both of those breakers as well. Same exact ones, but not per battery. Both the negative and positive from combiner are connected to one of those midnite 250s each when they enter the e-panel.

 

[Citlalatonac]

I'm a bit surprised nobody has left any comments. Oh well, I hope at least someone is learning something from this journey. It's been a fairly all-encompassing project with regards to my time.

Anyway, I installed the Halo UltraGrip (HUG) mounts on my roof last weekend. I cut the rails as well and joined them together with BOSS splices. To note, I first used a metal chop saw and that was absolutely the loudest method possible, I found. Perhaps I had the wrong wheel on it. I figured the stock wheel would cut through. It did but I'm pretty sure I ruined my ears at certain frequencies. What am I going to do, stop cutting and go put in ear protection? What am I, some sissy? In any case, it was this:
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After the ringing stopped, I unplugged that thing and instead used my band saw. Holy smokes, night and day difference. I used it while my son was napping and had no worries of waking him up. It actually cut instead of melting the aluminum. I just let the weight of my arm on the handle cut through the rails. Beautiful cuts, and WAY less material lost in cutting. I love this little thing, highly recommended. Great $100 investment for metal cutting:
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In any case, the HUG attachments were fairly straightforward to install. Snap lines, find rafters, lag bolt them in. I used multiple tools to try to find the rafters. I even tried using a 'magnespot' tool, which is supposed to be the ultimate. I put the transmitter right next to a rafter in the attic, flush with the deck. Then went on the roof and used the locator. Drilled through. Missed the rafter. WTF? Went into the attic and I drilled almost directly between two rafters. WTF? So I don't know what is up, if I got a defective one or what. I'll be returning it because it's not cheap. End of the day, a standard stud finder and tape measure worked best. I covered up any mistake holes with SolarSeal 9000, which is an approved sealant by Ironridge. Maybe today I'll be able to get the rails up there, we'll see. That's it for now.
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What made you choose the HUGs? The flashfoot design really makes sense to me, but they are more expensive and I'm just going off looking good.

 

[SparkyJJO]

I needed to cut metal better than using a hacksaw and I almost bought one of those chop saws. Got a band saw like you ahve instead. So thankful I did.

 

[Disturbedfuel15]

What made you choose the HUGs? The flashfoot design really makes sense to me, but they are more expensive and I'm just going off looking good.

Easiest to install in my opinion. Other than that, no reason. Both are certified not to leak so whatever was easiest and fit my budget. I'm very glad I went with them because they were very easy to install.