The California Multifamily Affordable Solar Housing (MASH) program was created in 2008 to offer advanced solar incentives to eligible affordable multifamily housing residences. These incentives are typically offered in the form of a one-time rebate given at the end of the project.
The California Public Utilities Commission (CPUC) was in charge of the program's administration. And the program was carried out by Southern California Edison (SCE), Pacific Gas & Electric Company (PG&E), and the Center for Sustainable Energy in San Diego Gas & Electric's (SDG&E) service area.
MASH has resulted in the installation of more than 23 megawatts (MW) of solar capacity since it began in 2008. There have been nearly 360 solar installations on multifamily buildings serving over 6,500 low-income households across the state.
The program's objectives were to:
The Multifamily Affordable Solar Housing (MASH) program in California has made solar energy available to tens of thousands of multifamily building owners and tenants throughout the state. This has allowed them to reduce carbon emissions and save money on energy costs.
MASH uses financial incentives and an innovative billing arrangement to solve the issue of persuading building owners to invest in renewable technologies. This was achieved with tenant units where the tenants pay their own utility bills, a barrier commonly known as a "split incentive."
In addition, the Multifamily Affordable Solar Housing (MASH) program offers a "virtual net metering" tariff. This tariff allows all tenants to benefit from the lower electricity costs generated by the solar energy system of the building.
From 2011 to 2013, MASH solar photovoltaic (PV) systems prevented over 27,450 kilograms of CO2 emissions. This is equal to an entire year's worth of energy-related emissions from approximately 2,600 households.
In buildings that have implemented virtual net metering, tenants' annual electricity costs have decreased by an average of $480.
As of 2023, demand for MASH incentives has significantly outstripped supply, and the current program is at capacity.
For solar energy systems that meet certain requirements, the MASH program offers rebates to owners of multifamily low-income residences. These rebates are given in a single lump sum using the Expected Performance-Based Buydown (EPBB) approach.
The EPBB, which was initially created under CSI, determines the generating capability of a solar energy system based on confirmed characteristics. Location, system size, tilt, shading, and orientation are examples of these features.
To calculate the total rebate, the capacity is multiplied by a design factor that contrasts the system's estimated performance with an ideal system installed in the same place.
Note: Rebates typically cover 30 to 40 percent of the system's installation expenses and are meant for eligible systems up to the first 1 MW of generating capacity.
The MASH program's goal seeks to combine the administrative simplicity of a one-time refund disbursement with an incentive structure that offers a higher rebate for systems that benefit tenants by lowering their energy bills.
Building owners can use the rebates, which the program offers in two stages, to lower their initial capital costs for the installation of the solar energy systems:
MASH projects can be as small as 10 kW or as large as 300 kW the majority are between 25 and 50 kW, with total fixed costs averaging between $150,000 and $300,000 before rebates.
In 2009, the CPUC added a virtual net metering tariff to MASH to ensure that occupants can take advantage of solar energy systems installed on their buildings. Virtual net metering has reduced the annual electricity expenses of participating tenants by an average of $480 per unit.
Under virtual net metering, a PV system generates enough electricity to cover the demand of both common areas and tenant units. The system distributes all of its generated electricity directly into the utility grid.
The utility then credits the building owner's and tenants' individual accounts with the kilowatt-hours generated by the PV system. This is done in accordance with a predetermined allocation agreement.
Virtual net metering reduces the cost of electricity for all residents of a low-income housing complex. The program does this without requiring the PV system to be physically connected to each tenant's meter. Additionally, it eliminates substantial hardware and installation costs, reducing the total cost of the system.
Many low-income Californians that might not otherwise have access to carbon-free solar energy now have it thanks to the MASH initiative. Building owners also profited from the program because it decreased their capital expenses and energy costs.
The MASH solar energy systems reportedly prevented more than 27,450 tons of CO2 emissions from 2011 to 2013. This amount is roughly equal to the annual energy-related emissions from 2,600 typical American houses.
Since its inception in 2008 through December 31, 2015, the MASH program has completed nearly 360 solar projects statewide. This added more than 23 MW of electricity-generating capacity, according to CSI's official public reporting. A total of 216 extra projects with a combined capacity of almost 36 MW are in the pipeline.
The virtual net metering tariff has enabled participating tenants to reduce their electricity bills by an average of $480 per year (based on data from 2011 to 2013).This was because they had direct access to electricity credits accrued from the solar energy systems installed on their buildings.
More than 6,500 tenant units were enlisted in the MASH virtual net metering tariff as of December 31, 2015.