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Toolkits Offer Pathway to Multifamily Solar

Increasing stakeholder resources for virtual net metering

The Center for Sustainable Energy (CSE) now offers online toolkits for solar contractors and multifamily property owners that provide resources for virtual net metering projects in each large investor-owned utility (IOU) territory. 

The toolkits were developed as part of an award to CSE from the Solar Market Pathways Virtual Net Metering Market Development Project, a Department of Energy-funded research project under the SunShot Initiative. It is aimed at expanding solar access to renters and tenants by increasing solar adoption within the multitenant, multifamily building sector. 

Virtual net metering (NEM-V) is a program offered by the IOUs that allows such building owners to install a single solar electric system and share the solar generation among the tenants’ utility accounts. The program became available to market-rate customers in 2012 but has been severely underutilized since then. 

“Nearly all of the residential solar energy installations in California have been made on single-family housing, yet a third of the state’s residents live in multi-unit dwellings,” said Ben Airth, CSE’s senior manager for renewable energy.

Airth said there are several hundred thousand multifamily properties, mostly apartments, in California that could take advantage of shared solar resources, but only about a hundred are doing so now. The multifamily housing stock is especially prevalent in the three largest cities in California, with over 40% of the households located in Los Angeles and San Francisco.

CSE’s online Solar Toolkits provide resources to multifamily property owners and solar contractors on how to efficiently and effectively navigate the process of utilizing NEM-V for solar for projects. 

Property owners will find a step-by-step guide on how to prepare for going solar and interactive worksheets to track energy-related information.

The Contractor Toolkit is designed to serve as a hub for virtual net metering resources, including an interactive multifamily building stock map, information on tariff interconnection processes and forms for each IOU territory. The map assists contractors in identifying regions with a dense multifamily building stock in order to support targeted marketing efforts and customer acquisition. 

Currently, six counties have maps: Alameda, Fresno, Los Angeles, Santa Monica, San Francisco and San Diego. The data allow contractors to find out which ZIP codes contain the greatest volume of apartments and condos and, in some cases, can be filtered by building size and type. Building types include apartment buildings and condo complexes in both the market-rate and affordable housing sectors. While it does not provide specific addresses or property contact information, contractors can use other available mapping tools to access street level views and assess rooftop solar potential.

The maps were created using county assessor secured roll datasets utilizing information on land use code, tax parcel code, number of units, address and more. Small units are defined as buildings with 2-9 units, medium buildings are defined as buildings having 10-19 units and large buildings are defined as having 20 or more units. 

If you have questions or ideas for additional resources that could supplement the toolkits, please email CSE at

October - November 2016
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