"Among Xcel Energy's 1.5 million customers in Colorado, only about five households have achieved net zero energy status, utility officials estimate. Not many homeowners have embraced zero energy because it's expensive. Building a new home with the equipment and materials needed for zero energy requires a minimum extra investment of $20,000 to $70,000 above the price of a conventional home, with a payback period of up to 30 years at today's energy prices."
"Many utilities, including Xcel Energy, allow homeowners to sell excess solar electricity back to the grid through a process called net metering. By tying photovoltaic electric production to a net meter, homeowners can offset the cost of power they purchase from the utility at night or during cloudy periods when the solar panels don't produce."
This is an example of the extreme demand reduction that is possible in some segments of the energy industry.
Phase control is measured by the "power factor," which should normally be close to 1. This is not an issue for the relatively small and simple loads that households normally put on the grid. Industrial customers must provide a load that is resistive, neither inductive nor capacitive, and they pay a penalty if this is not achieved. For example, if a factory has a lot of electric motors, it will have to pay a power factor penalty because they are not resistive loads.
If you're supplying electricity to the grid, you must follow the same rules--in reverse, sort of--and if you don't then the system gets messed up. So as I understand it, the issue for the electric company when net metering is used, is to make sure that the electricity supplied to the grid meets the phase requirements--plus a bunch of other rules. That's something that they normally don't need to worry about with residential customers, so it's an incremental burden on them.
Here is a list of rules that one utility requires you to follow. They're pretty complex, and "somebody" has to make sure, in a net metering environment, that they're being follwed. http://www.chelanpud.org/Snap/Interconnection.htm
