Electricity Supply Limited (SECL) has been the player involved both in generation and transmission of electricity. The study aims at forecasting annual electricity consumption of the company and suggest an optimal combination of renewable options namely wind, small hydro, solar photo voltaic, solar thermal and biomass to meet the RPO targets of subsequent 25 years. A linear regression model has been used for forecasting the consumption and RPO contributions whereas linear programming model has been used for determining the optimal combination of renewable sources under consideration over the segments of generation and short term power purchase agreements for meeting overall REC requirement from non-solar and solar sources. The study recommends for long term PPAs of 1 MW for wind, 30 MW of small hydro and 20MW of biomass instead of 1-year short term PPA and a need for promoting wind farms in the near future.