The power in your house most likely comes from a traditional electrical grid, designed to reliably deliver electricity from suppliers to consumers. These grids where designed in the 1960s and they seem overdue for a major renovation. From wikipedia:
Through the 1970s to the 1990s, growing demand led to increasing numbers of power stations. In some areas, supply of electricity, especially at peak times, could not keep up with this demand, resulting in poor power quality including blackouts, power cuts, and brownouts.
Smart grids go one step further by incorporating two-way communication systems that monitor and control how and when the electricity delivered is being used and can help manage electrical loads. But they can only do very little if everyone is switching on the A/C at the same time:
Grid 2030 is a joint vision statement for the U.S. electrical system developed by the electric utility industry, equipment manufacturers, information technology providers, federal and state government agencies, interest groups, universities, and national laboratories.
The modern smart grid is an attempt to leverage newer, low-cost electronics to extend grid management into individual homes and businesses – but the real break thru can only be reached by distributed energy grids because 15% of the power is still lost on the transport from the big power plants.