Understanding and Improving Solar Water Heater Effectiveness in California Households
Improving penetration of solar water heating through understanding of social, technical, and market factors
Regents of the University of California, Davis
Recipient
Davis, CA
Recipient Location
3rd
Senate District
4th
Assembly District
$499,310
Amount Spent
Completed
Project Status
Project Result
Employing a range of qualitative and quantitative methodologies, the research team performed an analysis of solar water heating technologies installed in California. Methods and data used include the CSI-T database, case studies of successful solar water heating markets, analysis of contractors and installations in California, interviews with industry experts, surveys of households with solar water heaters, and successfully securing utility data of energy consumption before and after installation of solar water heaters. An investigation of factors that are favorable to successful installation and use of solar water heating has been completed along with knowledge transfer across diverse stakeholder groups that do not typically overlap. The final report was published in December 2019.
The Issue
California has invested substantially in the adoption of solar water heating (SWH) to reduce residential GHG emissions. However, SWH has extremely low penetration despite environmental benefits and State investment. In 2010, the California Solar Initiative Thermal (CSI-T) program began providing subsidies to encourage cost-effective SWH. Authorizing legislation aimed for 200,000 installations by 2017, but fewer than 10,000 applicants were filed as of June 2019. To meet energy and climate-related goals, it is imperative to understand the potential role of solar water heating in displacing natural gas consumption for residential hot water use.
Project Innovation
This research assessed the performance and potential of natural gas-displacing solar water heaters in single-family homes in California. This assessment considers the possible scale and scope of solar water heating in the context of low natural gas prices, high system costs, doubts about field performance, and perceived availability of better alternatives. The research documented diversity in user satisfaction and perceived system performance, and a qualified decrease in project costs to below $5000 per installation. The research also found clusters of low-income installations successfully fostered through community action agencies. These community agencies were key to reducing installation costs. The suitability of solar water heating for California households is not purely a matter of cost-effectiveness within a typical energy efficiency framework, but also of evolving perceptions and values in the context of ongoing energy transformation.[br /]
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Project Benefits
This research supports California's energy goals by providing a clear picture of technology adoption issues related to the performance of SWH and demonstrating holistic technology assessment, which will be crucial to a successful transition. Currently, single-family residential solar water heating is not positioned to play a large role in emission reduction policies. The research shows, however, that solar water heating could contribute to decarbonization efforts and benefit some households in its current form. Improvements are possible in further strengthening performance reliability, lowering installed cost (e.g., through simpler systems, workforce learning, etc.), pinpointing good candidates for solar water heating, and increasing awareness amongst potential users. The research also demonstrates how holistic technology assessment can support California's clean energy transition.
Environmental Sustainability
Research provides a basis for increasing environmental benefits from SWH in California's single family home sector by clarifying technical and human factors that affect performance of SWH, delineating opportunities for improved performance, and identifying specific application that could yield the greatest benefits.
Key Project Members
Sarah Outcoult
Subrecipients
Ghoulem Research
Match Partners
Southern California Gas Company (SoCalGas)
