Splitting tails for solar supply

[Electricalpete]

Hi,

Can I ask for your opinions on the below please.

I am planning to get a 10kw solar system installed, eventually with battery back up, and I’m planning on putting all of the control gear on a wall in my garage.

The garage is only about 2m away from the edge of the house, however this makes it about a 15m cable run from the board.

So I’m thinking about putting a new board in the garage, to run the solar gear, battery backup, and a car charger.

The existing house distribution board is just above the external electricity box, on the other side of the wall. TN-C-S supply.

Usually the tails would be split at the incomer using a Henley block and then a switch fuse installed within 3m to the run the supply to the new garage board, however I don’t really have any room to install a switch fuse unit or install one where it wouldn’t look unsightly.

So my plan is to replace the old seventeenth edition board, with a new eighteenth edition board, and installing it as follows.

The old board is a split load board with 13 circuits installed, six on one RCD, seven off the other RCD

My plan is to put all 13 circuits on RCBO’s on the new eighteenth edition board fed from the main switch and utilising the SPD’s and then spilt the incoming cable using a split load link kit at the main switch, and then install a 50 Amp MCB (possibly an RCD, as this cable is now effectively a sub main feeding the garage, so not separate tails), by itself off the link kit to feed the garage board , so this is effectively the switch fuse to protect the supply for the board, but it part of the main board, I hope that makes sense.

So both boards will be fed from the same tails, and the tails will be protected by the 100Amp BS88 incomer, however the splitting will effectively be done in the board, with the boards main switch isolating everything.

But the solar back feed will only be through the 50 amp MCB, and back through the split load link kit through the main switch and back to the tails.

So just a question if anybody can foresee any issues with carrying out the installation in this way, or if it will not comply for the regulations for any reason, before I spend the time and money installing this.

I just want to overcome installing a switch fuse unit really, as this will look awful in the house, and there is no room for one in the meter intake.

Any thoughts as to possible issues that could occur, or indeed conformation this would be fine, or an alternative solution, would be appreciated.

Thanks

Peter.

 

[binky]

you could use a mini board, main switch and 50Amp MCB for the sub main, it's a lot smaller than a switch fuse, cheaper and does the same job.

Sub main doesn't need RCD, plus RCDs and solar inverters don't always work well together. RCD what you need to at the garage end.

 

[Electricalpete]

Hi Binky,

Thanks for the reply

Good to rule out the RCD.

My thought was to effectively make the mini board within the main distribution board, so have the split load link feed another main switch plus MCB on say the lefthand side of the board to feed the garage, then have the rest of the house fed as normal on RCBO's off the righthand side of the board, so effectively two boards in one.

So wanted to check if there were any issues with doing it this way.

Any thoughts would be appreciated.

 

[johnb2713]

Dont forget you will need CT's on the incoming tails.

 

[Murdoch]

is it easy to get the OK for 10 kwh panel systems these days?

 

[Fleeting]

The submain may need rcd protection if fault protection is not satisfied by the protective device.