So I wanted an integrated, small-scale (lights and plugs only) UPS-like system for my house, rather than a full fat solar setup.

I approached a renewables company local to me and they advised that I buy an inverter from them and they would give me one of their installers to do the job. Unfortunately I misconstrued the arrangement as their installers only do the AC side and the owner of the company would normally come in after and do the DC side (included in the job quote if I went via the company for the whole job).

 

Anyway, fast forward and I now have a 24v Mecer 3KW system installed and 4x12v 180ah lead acid batteries which will of course be used in 2 banks of 2 each. I will need to figure out how to get the DC side connected properly.

I need some advice on the following:

1) DC cable size. Inverter manual indicates 35mm², but most installations I've seen in person use 25mm²

2) A fuse for the cable is the bare minimum, but I also understand the value of having a DC breaker/isolator as well. Would something like this suffice with fused connections (avoiding the need for separate fuses) and am I selecting the correct amperage for my setup? https://powerforum-store.co.za/collections/featured-products/products/keto-battery-disconnector-with-160a-fuses

 

Expert advise would be appreciated!

Edited May 17, 20224 yr by Acheron

On 2022/05/17 at 7:56 PM, Acheron said:

So I wanted an integrated, small-scale (lights and plugs only) UPS-like system for my house, rather than a full fat solar setup.

I approached a renewables company local to me and they advised that I buy an inverter from them and they would give me one of their installers to do the job. Unfortunately I misconstrued the arrangement as their installers only do the AC side and the owner of the company would normally come in after and do the DC side (included in the job quote if I went via the company for the whole job).

 

Anyway, fast forward and I now have a 24v Mecer 3KW system installed and 4x12v 180ah lead acid batteries which will of course be used in 2 banks of 2 each. I will need to figure out how to get the DC side connected properly.

I need some advice on the following:

1) DC cable size. Inverter manual indicates 35mm², but most installations I've seen in person use 25mm²

2) A fuse for the cable is the bare minimum, but I also understand the value of having a DC breaker/isolator as well. Would something like this suffice with fused connections (avoiding the need for separate fuses) and am I selecting the correct amperage for my setup? https://powerforum-store.co.za/collections/featured-products/products/keto-battery-disconnector-with-160a-fuses

 

Expert advise would be appreciated!

Fused unit is fine as in your link.  If the distance between battery and inverter is less than 1m then 25sq mm is fine for your inverter but then the fuses need to be no more than 125A. With 35sq mm you can use the 160A fuses as per link.