SAO PAULO, Jan 8 (Reuters) - Private equity infrastructure fund I Squared Capital said on Monday it would acquire a 49% stake in Brazilian energy firm Origo Energia for up to $400 million, marking its first direct investment in Latin America's largest economy.

Origo operates on a distributed energy generation model, building photovoltaic solar plants and offering quotas of the electricity produced to small- and medium-sized companies and homes, who, in turn, receive discounts on their energy bill.

Proceeds of the deal will be used to fund solar projects totaling more than 2 gigawatts (GW) of capacity in 20 states across Brazil for an estimated capital expenditure of 6 billion reais ($1.23 billion), I Squared said in a statement.

Origo Energia has more than 100,000 customers and 300 megawatts-peak (MWp) in operational solar assets across several states.

($1 = 4.8788 reais) (Reporting by Leticia Fucuchima; Writing by Peter Frontini)