Is a “net-zero” house the same thing as an “off-the-grid” house?
Not necessarily, thanks to an invention called net-metering. Most green homes in metropolitan areas remain connected to the power grid. They use photovoltaics to produce power, but do not store the power (eliminating the need for expensive batteries). When they produce excess power, they sell that power to the power company. Their electric meter actually runs backward! On cloudy days or high use times, they purchase power from the power company. But at the end of the year, if all works right, the sum is zero.
