In this paper, methods of integrating solar energy into oil and gas industries are proposed. There are numerous applications of solar energy in oil and gas industries; however, this paper particularly aims to utilize solar energy for producing hydrogen, which required in hydrothreater unit of heavy crude oil upgrader process. Each proposed method is designed to have hydrogen production capacity equals to that required in the upgrader process. Three hydrogen production processes from solar energy are proposed, namely, solar steam reforming of natural gas using a volumetric receiver reactor, solar steam reforming of natural gas using molten salt as a heat carrier, and electrolysis of water using solar thermal energy. The three methods were compared with conventional process, steam reforming of natural gas. Process designs were carried out using Aspen Plus _­and System Advisor Model (SAM) to determine proper capacity of the technologies in the process, as well as required raw materials and utilities. Based on the process design, economic analyses on all processes were performed and the levelized cost of hydrogen production for different pathways (LCHP) was calculated. The result show that the solar steam reforming of natural gas process using a volumetric receiver reactor has the minimum LCHP of 2.514 $ per kg H₂, which is 46% higher than that of the conventional process.