Arcata, Humboldt County -- Just past noon on a hazy, raw Sunday a few weeks ago, Linda Parkinson did what few homeowners in this storm-battered region could: She turned on the television. While most Humboldt County residents were reeling from power outages left by devastating rains, Parkinson had electricity to spare. She cooked a feast for a dozen people, took hot showers and threw video-game parties for her 15-year-old son's classmates. For 24 years, Parkinson, 49, has lived completely off the electric grid, drawing energy exclusively from solar, propane and other renewable on-site power sources. She isn't alone. Some 180,000...