Hugh Pickens writes "Jonathan Fahey writes for AP that as the first mass-market electric cars go on sale next month, the power industry faces a huge growth opportunity, with SoCal Edison expecting to be charging 100,000 cars by 2015 and California setting a goal of 1 million electric vehicles by 2020. But utility executives are worried that the difficulty of keeping the lights on for the first crop of buyers — and their neighbors — could slow the growth of this industry because it's inevitable that electric utilities will suffer some difficulties early on. 'We are all going to be a lot smarter two years from now,' says Mark Perry, director of product planning for Nissan North America. When plugged into a home charging station the first Leafs and Volts will draw 3,300 Watts and take about 8 hours to deliver a full charge, but both carmakers may soon boost that to 6,600 Watts. The Tesla Roadster, an electric sports car with a huge battery, can draw 16,800 Watts. That means that adding an electric vehicle or two to a neighborhood can be like adding another house, and it can stress the equipment that services those houses. The problem is that transformers that distribute power from the electrical grid to homes are often designed to handle less than about 12,000 watts so the extra stress on a transformer from one or two electric vehicles could cause it to overheat and fail, knocking out power to the block."