NEW DELHI, Oct 10 (Reuters) - Indian conglomerate Reliance Industries Ltd (RELI.NS) on Sunday announced two deals to buy solar capacity, as the owner of the world's biggest refining complex seeks to become net carbon zero by 2035 and make India a hub for low-cost solar manufacture.

Through its unit Reliance New Energy Solar Ltd (RNESL), Reliance is buying Norwegian-headquartered solar panel maker REC Solar Holdings for $771 million from China National Bluestar (Group) Co Ltd and an up to 40% stake in India's Sterling and Wilson Solar (STEN.NS).

Reliance in June said it would invest $10.1 billion in clean energy over three years.

Owned by Asia's richest man, Mukesh Ambani, the company plans to build solar capacity of at least 100 gigawatts (GW) by 2030, accounting for over a fifth of India's target of installing 450 GW by the end of this decade.

Ambani said in a statement on Sunday, Reliance was ready to set up "a global scale integrated photovoltaic giga factory" with initial annual capacity of 4 GW, eventually rising to 10 GW.

He said buying REC Solar would help Reliance to expand in Australia, Europe, the United States and also elsewhere in Asia and that it was seeking to make India a hub for the manufacture of the lowest cost, highest efficiency solar panels.

All fossil fuel companies are under pressure from investors and campaigners to reduce emissions to limit global warming and oil majors including Royal Dutch Shell Plc (RDSa.L) and BP Plc (BP.L) have set goals to become net zero-carbon firms by 2050.

In August, RNSEL said it would invest $50 million in U.S. energy storage company Ambri Inc