Please share comments about my design with unprotected bus bar.
Components:
3x Multiplus-II 15k
4x RS-MPPT 540|200
9x modified lynx power-in (M8)
1x Pytes hub
48 x Pytes E-BOX
There is potential it will roast itself.
At least fuse each stack.
It seems you haven’t looked at all diagrams. Every component is protected by itself but because of staggered design (no clear disconnect between sections: chargers, batteries and inverters) bus is not.
I am wondering how this can be achieved in practice - maybe bus can be segmented with two or three shunts with 800A to limit splash damage.
I guess i missed the lightheartedness and sarcasm last night before bed. 
Ok so the roast request…
Bold design! You’ve essentially built a protection system to protect your protection system — the fuses already on every component are doing the heavy lifting here, so the segmentation is more of an overachieving backup dancer than a lead act.
The splash damage analogy is great though, even if the solution is a bit like buying flood insurance for a house that’s already on a hill. Points for thoroughness, invoice is going to sting a little.
The inverter is going to see one phase go down and shutdown in fault anyway, so your beautifully segmented, lovingly fused, shunt-monitored bus will protect a system that’s already decided to stop working.
10/10 for creativity, 4/10 for practicality, and a solid 7/10 for making the BOM more expensive than it needed to be. 
Look you gave shown that you know what you are doing with the components, you have got a bit tangled up convincing yourself there’s a protection gap that doesn’t really exist.
So your two justifications for the segmentation:
Fault isolation — handled by the fuses already on every component
Maintenance or segment isolation if it wasconsidered — irrelevant because you’d de-energise the whole system anyway when working on it.
Your most likely problem will be fire and fuses do nothing in that circumstance.
Making sure everything is torqued and has good connections.
Retorqued or checked after initial loading and periodic checks after.
Is it condescension or parsimony with regard to the number of nominations?
More awards could certainly have been given 
One can even afford a wry smile on a serious note, provided you are familiar with the concept of physico-electrical geometry. This is a task involving the design of interconnection matrices and current distribution for parallel battery modules.
Really not my intention to steal your topic but right now building a very similar system:
3 x Multiplus-II 15k
1 x RS-MPPT 450|200 (future expansion for winter days)
5 x modified lynx power-in (M10)
8 x Dyness PowerBrick 16KWh
1 x existing Fronius ECO 27-3 with 32KW panels
Batteries are fused with NH00 125A gB, this also adds disconnect capability.
Multiplus II and future RS-MPPT are fused with Mega fuses, no in between Lynx fuses.
My biggest concern being the busbar capacity, in the components distribution I am making sure that every MPII is having at least 2 batteries on the same Lynx Power-in.
Really interested in your project ongoing.
I am grateful for your responses. They are reinforcing me that I go in right direction. I understand that there may be many ‘right directions’ but it is good to know that my idea does not belong to wrong way category.
Just to expand on reasoning - all those fuses are meant to protect connections (cables) because as you said devices themselves are already protected. Reason I mentioned that bus does not have any protection is that if it gets shorted (operating error) there is only physical protection (covers) to prevent disaster but no fuse. I guess I did go too far here but my heritage is Polish forum elektroda.pl full of regulations citing zealots …
During the process I realized that connectivity is always the main problem to resolve and solution is always a balance between cost an safety and another one between buy and DIY.
I browsed many forums and I am surprised that there is very little practical information regarding connecting system together. I see people figuring out things for themselves and often I find that people do make all sorts of things that can be considered errors (like lack of ventilation) so I thought that bringing this topic may be useful for everyone because sooner or later we all face such problem.
Because there is a difference between DIY and professional… The professionals don’t need to ask -they know the regulations and safety concerns.
Knowing what is right/safe for your set up and its use is important and being able to forsee and provision for all circumstances.
And keeping a balance as well. It is easy to go overboard (and easier to skip the cost too but pay later.)
My stance is if the bus bar is uncovered, it should not be energised. Especially not with 48v live many amps of batteries attached. You are no longer playing and cannot be casual - the right SOP should be followed. Safety 101.
I meant that you have already fused each device so they are protected (besides their own internal protection) so a segmented bus bar fuse is overkill and actually not likely to blow if the bus bar is shorted.
It is okay to share topic 
Today I’m buying batteries and Lynx bus bar components. After I put everything together I will take measurements and will order/make cables as short as it is practical.
With my current experience I can say following:
When it comes to currents you can make calculation as I did. Ignore inter-module connections. I don’t think they make any practical difference (millivolts at worst). Focus on current flow on sections between components. There are different opinions circulating but keeping maximal potential current flow on a section below 500A should make a good system. I couldn’t find what is the maximum run for 1000A bus but I guess it will be couple modules. So if you stagger components to prevent bottlenecks you should be fine. I couldn’t find a source that says you should not do that.
Prepare a schematic and I’m sure someone will help you correcting mistakes (if you made them).
So my concern is you are relying on megafuse with tiny 2k aic rating to handle available fault current from four pytes lfp batteries in parallel…
Imo you need class t fuse (20k aic) (Via class t power in?), midnite/carlingtech mnedc250 (50k aic) or an NH style fuse to handle the available lfp fault current.
Why would you not mount the lynx covers on to cover the busbars?
Hello.
Again, thank you for valuable piece of insight.
Busbars will be covered - mockup image is to show intention where I want to connect each device and use which fuse. Implementation will use covers and potentially additional temperature sensors to monitor bus.
Each battery segment is only two power banks - pair is capable of producing 200A in peak and 100A long term. Pytes E-BOX banks seem not to have typical fuses so I assume manufacturer decided that they are not beneficial somehow. I put fuse on each connection just to protect cable. I have 24 pairs so I expect low currents on each and I will probably lower BMC current limits.
Do you think megafuse won’t be able to disconnect current that betteries may produce during catastrophic malfunction ? What kind of malfunction ? I specifically chose bank that has automotive batteries.
Ok when you say unprotected/uncovered and splash protection I thought you were operating with covers off and busbars exposed. Perhaps a language difference.
Megafuse doesnt have the aic rating for 48V lfp and thats why Victron introduced the Class t power ins.
If I was laying this out without using midnite/carlingtech breakers id do this:
Three class t power ins. 6 class t fused 4/0 connections to each battery stack of 8. Then lynx shunt m10 1000A, then four more class t power ins for your inverters and rs450s, interleaving sccs and inverters along the bus. This way the lynx shunt will give you accurate soc when the pylontechs may drift with smaller undetected loads.
To me it makes no sense to segment the power bus with 800A fuses. Potentially could use an 800A cnn fuse in the lynx shunt to seperate batteries from loads but in my system I use the solid busbar that comes with the m10 lynx shunt instead of a system fuse.
For effective protection on battery connections, using Lynx system, Adler EF3 is an option but does not offer disconnect capability.
That is why I preffer NH00 socket and fuse, specifically gBat or the high speed aR type.
What I meant by splash damage is type of collateral when for example failed capacitor in power supply takes down transistor, and other components around it.
I dropped idea of segmenting bus this way following advice on this thread. What I will do instead is to focus on control to catch issues in advance and prevent situations where physical safety measures have to kick in. For example one of the ideas is to use additional temperature sensors on devices to monitor bus temperature on segments - I will have seven otherwise unused sensors.
Pytes E-BOX allows only stacking of two banks. It is not explained in the documentation as to why. I came up with idea of creating local bus bar inside each stack to connect 8 banks to local bar and then 6 local bars to main bus bar. I gave up on this idea though due to complications, DYI, and cost. I would have to build bus bar myself and find practical solutions to mount fuses, create shielding that allows enough airflow, etc, etc. System needs to be reliable enough so I can leave it unattended for periods of time hence I looked for similar solutions and experiences of their owners.
One fact I didn’t disclose is that I want to commission system few months before I start living there so I need to do in IKEA style. I will go there for few days and build system out of proven components that I will only have to connect together. DIY approach is usually ongoing process of modifications, expansions, and fixes and I can’t afford that. Whole 3 tonnes shipment arrives sometimes next week and I’m still working hard on getting solar panels solution which is another safety challenge
I’m guessing they don’t want too many units in parallel due to available fault currents and potentially AIC limits of the breakers they are using if any?
Also looks like pytes ebox is discontinued? Unless you are getting them on final clearance pricing?
“Please note: The capacity can be increased by connecting the batteries in parallel, but due to the limitations of BMS and power cable, Max. 16 batteries can be connected in parallel as a group without any additional kits and a bus bar should be used for connecting them together. Only batteries marked with C16 label on the battery carton and SN code support a maximum of 16 units in parallel in one group. Otherwise, only a maximum of 8 units in parallel is supported. Installations with greater than or equal to 8 batteries will require the: Pytes Battery Hub”