As you probably know, I’m preparing to install a heated windshield. As suggested firegrafik and ZZZhuk I replaced first my 110A alternator to 140A. I bought it from member of vwgolfv.pl. It’s regenerated with new regulator, new brushes, new NSK bearing (such as goes to the first assembly from factory), new commutator and changed clutch pulley (to fit my 6R).

New alternator

Alternator 140A VW 14V Valeo
Part number: 03L903023A
More info: www.elstock.dk/en/shop/#!list/all/03L903023A

Everyting works:

Voltage test

With the engine running:

On the engine off:

My old alternator 

036903024H 110A
www.elstock.dk/en/shop/product/28-4713