California's net-metering law originally took effect in 1996 and applies to all utilities with one exception*. The law has been amended numerous times since its enactment, most recently by SB 489 in October 2011, which extended net metering to all technologies eligible for the Renewables Portfolio Standard (RPS).
The original law applied to wind-energy systems, solar-electric systems and hybrid (wind/solar) systems. In September 2002, legislation (AB 2228) allowed biogas-electric facilities up to 1 MW to net meter until December 31, 2005, under a pilot program. This pilot program was extended until December 31, 2009, upon the enactment of AB 728 in September 2005. SB 489 did away with the pilot program, and instead allowed for biomass and all other RPS-eligible technologies to participate in net metering under the same terms available for solar and wind.
Other legislation enacted in October 2003 (AB 1214) made fuel cells eligible for net metering until the cumulative rated generating capacity of net-metered fuel cells reaches 112.5 MW statewide. AB 2165 increased the statewide maximum to 500 MW, and requires each utility to provide net metering for eligible fuel cells until it reaches its proportionate share of the 500 MW cap. Previously restricted to fuel cells that begin operation before January 1, 2014, AB 2165 of 2012 extended the eligibility deadline to January 1, 2015.
'''Aggregate Capacity Limit'''
Legislation enacted in 2006 (SB 1) increased the aggregate limit of net-metered systems in a utility's service territory from 0.5% to 2.5% of the utility's aggregate customer peak demand. AB 510 of 2010 further raised the aggregate limit to 5%. In practice, all three investor-owned utilities have interpreted "aggregate customer peak demand" differently, and are using different methodologies to calculate their net metering caps. The CPUC approved a [http://docs.cpuc.ca.gov/efile/PD/163814.pdf proposed decision] in May 2012 to more clearly define "aggregate customer peak demand" for all utilities. The decision defines aggregate customer peak demand as the sum of the non-coincident peak demands of all utility customers. Previously, the utilities had used the largest instantaneous peak demand as their reference point.
The CPUC decision also stipulates that net metering will be suspended for new customers at the end of calendar year 2014, pending the outcome of further CPUC proceedings. However, net metering will continue to be available to renewable customer-sited generation until the target for solar PV capacity under the California Solar Initiative has been reached.
'''Net Excess Generation'''
Net excess generation (NEG) is carried forward to a customer's next bill. Under prior law, any NEG remaining at the end of each 12-month period was granted to the customer's utility. [http://www.leginfo.ca.gov/pub/09-10/bill/asm/ab_0901-0950/ab_920_bill_20... AB 920] of 2009 gave customers who are net metering solar and wind systems two additional options for the NEG remaining after a 12 month period. Customers have the option of rolling over any remaining NEG from month-to-month indefinitely, or they can receive financial compensation from their utility for the remaining NEG. The CPUC set the compensation rate at the 12-month average spot market price for the hours of 7 am to 5 pm for the year in which the surplus power was generated. Click [http://www.cpuc.ca.gov/PUC/energy/DistGen/netsurplus.htm here] to read more about annual net surplus compensation. The rate making authorities of municipal utilities must develop their own compensation method for the remaining NEG through a public proceeding.
'''Renewable Energy Credits'''
The renewable energy credits (RECs) associated with the electricity produced and used on-site remain with the customer-generator. If, however, the customer chooses to receive financial compensation for the NEG remaining after a 12 month period, the utility will be granted the RECs associated with just that surplus they purchase.
'''Virtual Metering Options'''
[http://www.leginfo.ca.gov/pub/07-08/bill/asm/ab_2451-2500/ab_2466_bill_2... AB 2466] of 2008 allows a local government, if certain conditions are met, to distribute bill credits from a renewable energy system across more than one meter. To be eligible for this billing arrangement all electrical accounts involved must receive electricity under a time-of-use tariff, and all accounts must be owned by the same entity. Click [http://www.cpuc.ca.gov/PUC/energy/DistGen/RES-BCT.htm here] to learn more about the bill credit transfer program for local government.
California also allows virtual net metering for certain utility customers. Originally authorized just for customers participating in the Multifamily Affordable Solar Housing (MASH) program, the CPUC voted in July 2011 in favor of a [http://docs.cpuc.ca.gov/PUBLISHED/AGENDA_DECISION/138968.htm#P132_22399 proposed decision] which extends virtual net metering to all multi-tenant properties and to all distributed generation technologies. Virtual net metering allows the bill credits associated with the electricity produced by the system to be distributed across all the tenants' electricity bills. Click [http://www.cpuc.ca.gov/PUC/energy/DistGen/vnm.htm here] to read more about virtual net metering.
SB 594 of 2012 allowed for the possibility of meter aggregation under net metering pending a favorable determination by the CPUC and the ratemaking authorities of publicly-owned utilities. A single customer with multiple meters on contiguous property may elect to aggregate the electrical load of their meters and apply the generation credits of a renewable energy system also located on contiguous property to all of the meters. Before this meter aggregation is allowed, however, the CPUC must determine that meter aggregation will not increase the expected revenue obligations of other customers not participating in net metering. The bill requires the CPUC to make this determination by September 30, 2013. Similarly, the ratemaking authorities of publicly-owned utilities must make a favorable determination regarding the rate impact on its non-net metered customers before allowing meter aggregation. A publicly-owned utility must make this determination with 180 days of receiving the first request from a customer to aggregate their meters. If meter aggregation is allowed, participating customers will be ineligible to receive compensation for any net surplus generation remaining after a 12 month period as described above.
'''Restriction on Additional Fees'''
California does not allow any new or additional demand charges, standby charges, customer charges, minimum monthly charges, interconnection charges, or other charges that would increase an eligible customer-generator's costs beyond those of other customers in the rate class to which the eligible customer-generator would otherwise be assigned. The CPUC has explicitly ruled that technologies eligible for net metering (up to 1 MW) are exempt from interconnection application fees, as well as from initial and supplemental interconnection review fees.
Publicly owned utilities may elect to provide co-energy metering, which is the same as net-metering, but incorporates a time-of-use rate schedule. Customer-generators with systems sized between 10 kW and 1 MW who are subject to time-of-use rates are entitled to deliver electricity back to the system for the same time-of-use (including real-time) price that they pay for power purchases. However, time-of-use customers who choose to co-energy meter must pay for the metering equipment capable of making such measurements. Customer-generators retain ownership of all renewable-energy credits (RECs) associated with the generation of electricity they use on site.
* [http://www.pge.com/b2b/newgenerator/netenergymetering/ PG&E's net-metering web page]
* [http://www.sce.com/customergeneration/customer-generation.htm SCE's net-metering web page]
* [http://www.sdge.com/clean-energy/overview/overview SDG&E's net-metering web page]
''* Publicly-owned electric utilities with more than 750,000 customers which also provide water are exempt from offering net metering. Los Angeles Department of Water and Power (LADWP) is the only utility that falls in this category.''