A Net Zero home can be independent from the energy grid supply. Energy can be generated on-site usually through a combination of energy producing technologies like solar and wind - while reducing the overall use of energy with extremely efficient HVAC and lighting technologies.
The Net Zero home may use solar panels that blend into the roof, geothermal heating and cooling, and a high-tech system that allows control of climate and security using a smartphone or laptop. The purpose of the Net Zero home is to be completely independent from the utility electrical grid.
Read the USA Today article on Net Zero homes