It first revealed the planned 52.2 million yuan ($7.6 million) acquisition last November.
Forum will become a non-wholly owned unit of Comtec Solar Systems, with its financial statements to be consolidated with those of the group, according to a statement to the Hong Kong stock exchange.
Forum installs residential rooftop solar arrays throughout mainland China.
By the end of December, the Hong Kong-based developer is expected to complete about 15 MW of distributed-generation PV capacity.
It aims to connect 77 MW of rooftop capacity to the Chinese grid by the end of 2019.
The completion of Forum is part of Comtec’s ongoing expansion into downstream PV development, which is a future growth priority for the group.
In early January, Comtec said it expected to post a “substantial” net loss for the year to the end of December, partly because of its decision to sell production assets in Malaysia to Chinese silicon producer Longi at a steep discount of 200 million yuan.
It also revealed plans in January to install smart energy charging facilities for electric vehicles (EVs) in the Chinese city of Luoyang, Henan province.
Comtec — which produces silicon ingots and wafers — also unveiled plans in December to develop an undisclosed amount of solar capacity in Wuxi, Jiangsu province, over the next three years.