Net metering

Net metering (or net energy metering, NEM) allows consumers who generate some or all of their own electricity to use that electricity anytime, instead of when it is generated. This is particularly important with wind and solar, which are non-dispatchable. Monthly net metering allows consumers to use solar power generated during the day at night, or wind from a windy day later in the month. Annual net metering rolls over a net kilowatt credit to the following month, allowing solar power that was generated in July to be used in December, or wind power from March in August.

Net metering policies can vary significantly by country and by state or province: if net metering is available, if and how long you can keep your banked credits, and how much the credits are worth (retail/wholesale). Most net metering laws involve monthly roll over of kWh credits, a small monthly connection fee, require monthly payment of deficits (i.e. normal electric bill), and annual settlement of any residual credit. Unlike a feed-in tariff (FIT), which requires two meters, net metering uses a single, bi-directional meter and can measure current flowing in two directions. Net metering can be implemented solely as an accounting procedure, and requires no special metering, or even any prior arrangement or notification.

Net metering is an enabling policy designed to foster private investment in renewable energy.

Net metering originated in the United States, where small wind turbines and solar panels were connected to the electrical grid, and consumers wanted to be able to use the electricity generated at a different time or date from when it was generated. Minnesota is commonly cited as passing the first net metering law, in 1983, and allowed anyone generating less than 40 kW to either roll over any kilowatt credit to the next month, or be paid for the excess. In 2000 this was amended to compensation "at the average retail utility energy rate." This is the simplest and most general interpretation of net metering, and in addition allows small producers to sell electricity at the retail rate.

Utilities in Idaho adopted net metering in 1980, and in Arizona in 1981. Massachusetts adopted net metering in 1982. By 1998, 22 states or utilities therein had adopted net metering. Two California utilities initially adopted a monthly "net metering" charge, which included a "standby charge," until the PUC banned such charges. In 2005, all U.S. utilities were required to offer net metering "upon request." Excess generation is not addressed. As of 2017 43 U.S. states have adopted net metering, as well as utilities in 3 of the remaining states, leaving only 4 states without any established procedures for implementing net metering.

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Wikipedia