March 1 (Reuters) - Ontario's power grid operator expects more than 3,200 megawatts (MW) of renewable capacity to be connected to the transmission system, while the province's remaining coal-fired plants will shut over the next 18 months. In a report published on Thursday, the Independent Electricity System Operator (IESO) said the renewable capacity includes the Canadian province's first two transmission grid-connected solar projects. By August 2014, the IESO said total wind and solar generation connected to the transmission and distribution systems is expected to reach about 6,800 MW. "Integrating renewable resources into Ontario's changing supply mix has been a learning process for both us and the renewable generators," Bruce Campbell, IESO Vice-President of Resource Integration, said in the release. "Everything we've learned will be applied in the coming months as wind and solar gain even more prominence on the grid," he said. The grid operator also said the six remaining 475-MW coal-fired units at Lambton and Nanticoke are scheduled to stop burning coal by the end of 2013. In addition, the conversion of 211-MW Atikokan from a coal-fired plant to biomass is underway, with the unit expected to be in service by the third quarter of 2014. Despite these big changes, the IESO said Ontario will continue to have adequate generation and transmission capability to meet consumers' needs over the next 18 months. The IESO expects the use of electricity from the grid to decline by 0.9 percent in 2013 as consumers participate in more conservation programs and install generation capacity at their homes and businesses. In 2012, the IESO said electricity use increased 0.4 percent. For the summer of 2012, there were about 30,500 MW of generating capacity in Ontario with a peak demand of about 23,400 MW, according to a summer assessment from the North American Electric Reliability Corp (NERC), which is responsible for setting the region's reliability standards. In 2012, NERC said about 40 percent of the generating capacity in Ontario came from nuclear plants, 21 percent natural gas, 19 percent hydro, 11 percent coal, 7 percent oil and 2 percent renewable. The biggest generators in Ontario include units of province owned Ontario Power Generation, Bruce Power, Atco Ltd, Calpine Corp, TransCanada Corp and TranAlta Corp. Bruce Power is a partnership between TransCanada, Cameco and others.