When comparing the cost of an off-grid PV system on a new home to the cost of electricity from the grid, don’t forget to add line extension fees when calculating the lifetime cost of utility power. Line extension fees are the cost of connecting the home to already-existing utility wires. If your home or business is more than a few tenths of a mile from existing electric lines, you could be charged expensive line extension fees (up to $60,000 per mile in mountainous regions, according to the U.S. Department of Energy). Keep in mind that this only buys the installation of poles and electric lines. It does not buy you a single kilowatt-hour of electricity!