German firm RWE said over half the Siemens 3.6MW turbines are now generating electricity and exporting it to the mainland. The remaining turbines should be connected by the end of this year.
The milestone comes just over a year after the first electricity was exported from the site at the end of August 2013.
RWE project director Toby Edmonds is hopeful the development will be completed before Christmas but warned winter weather could push full commissioning into the new year.
Cabling at the site was held up in February with the discovery of underwater munitions. They were removed and, earlier this week, unexploded ordnance risk managers 6 Alpha Associates gave Gwynt y Mor the all clear.
Some array cables still need to be put in place at the project, located 13 kilometres from the North Wales coast. An RWE spokesperson said the cables should be installed by October or November.