Hey! Do you mean that by average, the connection loosens after three years? Also if the loosening is not related to thermal cycling, do you have any idea what would be the cause?
In relation to this, does anyone use Loctite or similar thread locker to secure busbar/other connections?
In relation to this, does anyone use Loctite or similar thread locker to secure busbar/other connections?
Most Loctite’s insulate so should not be used, i only use Loctite’s on my wind turbine nuts and bolts.
This is the stuff i use to protect the joints.
Thanks for the link! That makes sense especially since you use copper fasteners. I was thinking that since my stainless fasteners most likely don’t carry any relevant current i might sacrifice their electrical conduction for a more secure joint 
What you have to remember is each martial will have different requirements for torquing, so steel bolts into steel nuts will be different if screwing steel into lead battery connections or copper so you must be very careful not to damage the threads you’ve screwing into.
It’s always best to use the same martial for both bolt and nut if you can but this is not always possible.
Stainless bolts usually require lubrication for assembly, otherwise the bolt and the nut might fuse together upon torquing them to spec.
Generally a stainless fastener is also weaker (lower tensile strength) than its steel counterpart. Sure theres many different grades, but the most common grade 8.8 steel bolt is at about 880MPa while the most common grade 70 stainless is at 700MPa. Also keep in mind that stainless and aluminium have a relatively high galvanic reaction.
Most busbars i tend to work with are either bare copper or tin plated copper. Both get a light use of scotch bright at the contact points, and then steel fasteners including washers and a split washer, grade 8.8. After torquing to spec i mark each fastener with paint, from the boltthreads, over the nut, the washer to the busbar. So you can visually see if any of the elements move over time
use of scotch bright at the contact points
Lol me too 
Don’t need to worry about joints loosening if fasteners are fused together 
.
Jokes aside, I was thinking that the use of a suitable thread locker might help in a couple of ways.
It would mitigate the seizing effect which is common using stainless fasteners on certain materials.
It would ihibit mousture ingress resulting in reduced galvanic reaction.
And finally it would secure the joint to reduce the risk of them loosening in the future.
Most Locktite insulates mentioned in the thread.
Notes from the field - generalised so most likely don’t apply to your set up. A few have been mentioned in the thread already.
Often the size used is the size of copper bus bar (so is undersized actually)
Aluminium oxideses fast(er than you think). Often lugs and contact areas are not cleaned shortly beforehand as assembly is made, so are clamped on oxidised bar. The aluminium look is actually you looking at the oxidised surface (ignoring coating here)
They work loose. If not thermal cycling - possibly being distorted in initial torque? Maybe with a combo of above. The system can also have some harmonics or vibrations (also mentioned in the thread) harmonics is basically vibration - may not be a huge deal in your system.
When different material bolt is used it can work loose as there is different thermal properties. And then there is the corrosion because of dissimilar metals. (Moisture as a factor).
Thats not to say copper doesn’t have its issues. So not shooting the aluminium down. It just needs different considerations.
This is a 3200 amp 6.8meter busbar we built to carry the load of 9x15kva multiplus 2, 3 phase and 230kwh of battery storage and 200kw of solar. Built inside a container for our customer, this has also been built with an external transfer switch.
Will such an installation still be monitored by a “regular cerbo”, or do you have some kind of “business-versions” for this purpose? (Would assume that redundancy would be a desireable feature here)
Kept it standard, then easy to fix if a failure happens.
Really impressive!
How did you settle on Pylontech for batteries versus other options?
Especially when they’re 15S and limit the power from MPPTs.
To be honest we have done a lot with pylon and under the pro and cons, we have used other battery manufacturers and had issues with there BMS and needed it to be stable and due to the size of the bank not working them to hard.
That is a highly theoretical complaint 
PV is producing it’s maximum power only a few minutes per day, a few days a year. Absolutely neglectable to be capped in maximum DC Output power of the MPPTs at these times.
You’re wrong.
Please keep to the topic. Thanks
Thanks - interesting insight.
Could you please share and expound on the spreadsheet?
We often need busbars for high-current applications on tight spaces onboard yachts - here the custom-built 2000A main battery distribution we did for a 35m sailboat 
Parts are cut and bent from plain copper busbars in our workshop, then go to a subcontractor for galvanization.
Here the finished product onboard (hybrid generator system with 105kWh of LiFeP4 batteries, 24kVA Victron Quattro units and 4,5kWp PV):
