Hello,
we are just in final setup and together with my electrician I'm wondering about DC 
fusing and cables.
See picture attached.
- Are 300 A and 100 A ok?
- Are wires diameters fine?
- There are no additional fuses necessary, e.g. for individual batteries?
Thanks in advance for some feedback
David
The Multi 2 cabling and fusing can be checked here. The size of DC cable used is based on length.
The 250/70 here.
On the Pylons if you are using their kits will be good in pairs like that.
An example of 4x 3000C batteries in a kitchen cupboard and a thermal image taken an hour or so into an ESS scheduled overnight charge. Please don't be taken by the colour mapping (thermal cameras like to make things look exciting!) the temp readings are the important bit - Pylontech 25mm cables @31C (feel a bit warm to touch).
The inverter/charger is a 48/5000/70-35 Multiplus, so can sustain around 4400W, which with 52v (charging voltage) would be 84A. Given all of the detail involved in designing the ESS, I haven't really given this aspect too much thought - just followed the battery manual. And now reasonably satisfied 25mm cables are fine (just a 2 metre run) given that, in operation, they barely get warm.
Also wonder if there's a 'boys toys' thing going on with cable sizes. Your drawing looks perfectly adequate to me. I have a 50mm cable from Lynx Distributor to the Multi and, in operation, it is v adequate. Must say though, those 70mm cables would make it look a lot more important!
Fuse size is based on protecting the wire. Once you know the wire size then size the fuse accordingly.
This is a great calculator for both:
