The electric power industry worldwide has been focusing towards increasing utilization of renewable energy resources such as wind and solar to build and maintain clean, reliable and affordable electricity systems. Although these resources are environmentally clean, their uncertain and intermittent nature is a significant issue. Similarly, other energy generators such as nuclear and gas have serious environmental issues. These issues can be resolved with effective management of supply and demand using appropriate energy storage. Although various energy storage options are available, PHES is globally proven technology at grid level. Additionally, gravity power module (GPM) is a newly emerged technology in the power industry. However, its applications at full scale are still awaited. This research developed methodologies for integrated planning framework for PHES systems at grid level, employing a GIS-based model to identify feasible PHES sites, optimizing the scheduling of feasible PHES potential, and performing the financial analysis of PHES system. The methodologies were applied on grid-connected electricity area of Ontario that identified 285 feasible PHES and GPM sites with storage potential of 56,268 MWh. This research proposed the formation of a cooperative association namely „Pumped Hydro Storage Association (PHSA)‟ for integration of PHES system in the electricity market system operated by the IESO in Ontario. Using 2016 data, the optimization model resulted that PHSA supplied real-time energy 28,134 MWh/ day, provided ancillary services including variable operating reserve 23,914 MWh/ day, fixed operating reserve 4,220 MWh/ day, and purchased energy 65,060 MWh/ day. The optimization results and resultant financial indicators confirmed that proposed PHES system is technically and financially viable in a large electricity market system. As an initial step, partial development of PHES and GPM plants was proposed with an initial capital cost of C$ 1,052 Million utilizing 7,767 MWh/ day energy potential that resulted in a net profit share of C$ 13.36/ MWh for each participatory plant. Finally, the developed PHES planning framework for PHES system can certainly be found valuable to the policymakers, system operators, energy developers, research scholars, engineers, financial analysts and scientist community to work on future improvement in the PHES system.