Urgent techy help re Solar Panel Wiring or no Southport

So solar panel stuck on roof and covered up so no power being generated

Hole drilled in roof and wires from solar panel fed through taking great pains to retain live marker on appropriate wire.  All fittings and wire sikaflexed down.

Fitted controller in what I call the electric cupboard.

Pulled wires through top of cupboards and opps the live wire marker has disappeared

I know to wire the battery to the controller first but if I wire the solar panel incorrectly will the controller intervene and not let the system work.

I was having the solar panel fitted by someone but 'life' got in the way.

Uncover the panel and connect a voltmeter,you will be able to work out which is the live wire,  it will show as a -ve reading if you have terminals wrong way round

Sorted this evening - just have to see if the panel charges the batteries when the sun comes up   
 
I thought I had sussed the positive lead last night but confirmed it today with the voltmeter. Phew.

Thank you Ken