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Joshua Weiner
CEO at SepiSolar
Joshua Weiner is the CEO and founder of SepiSolar, Inc., a national solar-plus-storage design, engineering, and consulting company based in Fremont, California.12 He founded the company in 2009 and has been leading a growing team of designers, engineers, and technical consultants since then.4
Background and Education
Weiner holds a BA from the University of California, Berkeley, which he completed between 2001 and 2005.1 His educational background also includes a degree in Astrophysics & Astronomy from UC Berkeley.4
Professional Experience
Before founding SepiSolar, Weiner worked at Akeena Solar from 2005, where he quickly took on a supervisory role in the company's operations departments.4 His career in the solar industry includes:
- CEO at SepiSolar, Inc. (February 2009 - Present)12
- Director of Storage Integration at Nextracker Inc. (July 2015 - 2019)2
- Director of Engineering/Engineering Consultant at NRG Energy (February 2013 - February 2015)3
- Engineering Consultant at ENGIE Storage (January 2009 - July 2013)3
Expertise and Certifications
Weiner is a certified member of the North American Board of Certified Energy Practitioners (NABCEP) since 2007.3 He has taught advanced solar system design and project management at UC Berkeley.3 His areas of expertise include:
- Solar PV and energy storage design and engineering
- Renewable energy technologies and markets
- Project development and management
- Energy policy and finance
- Codes and standards in the solar industry3
Expert Witness Services
As CEO of SepiSolar, Weiner provides expert witness services and case review for construction law and civil litigation firms. He offers expertise in various aspects of solar and energy storage projects, including technology, contracts, finance, permits, and project development.3
SepiSolar, under Weiner's leadership, has worked on over 3900 commercial and industrial/utility projects, 540+ energy storage projects, and completed 11.5 GW of projects across 47 states.5


