About Rubix
Built By Installers, for Installers
Rubix designs and builds advanced solar battery storage solutions for people who expect more from their power. From off-grid needs to modern solar energy systems, we focus on reliability, smart design, and long-term value–all in a simple, installer-friendly form.
Rubix was founded by people who install, use, and depend on battery systems every day. We know job sites, system design, and customer expectations because we’ve lived them.
That experience shapes everything we build. Our modular designs simplify installs, and our dependable performance reduces callbacks.
Rubix isn’t just compatible with installer workflows.
It’s designed around them.
Who We Are
Rubix is a team of engineers and problem-solvers committed to better energy storage. We combine hands-on experience with good design to create batteries that perform in real-world conditions. Not just on paper.
Meet the Team
James Mast
Managing Partner, Rubix Battery
Since 2015, James has had a front-row seat in the off-grid solar industry, which has gone from difficult and impractical to easy and efficient. His company, Envirosol, has been instrumental in ushering in the era of lithium iron phosphate batteries, which have replaced their high-maintenance, lead-acid counterparts.
James currently fills an advisory role at Envirosol and serves as a managing partner at Rubix Battery LLC.
Lester Miller
Partner & Strategic Advisor, Rubix Battery
Lester Miller is the Executive Director of MillerTech Energy, leading with a focus on innovation, reliability, and customer-first service. Raised on a farm, he developed a strong work ethic and practical mindset that continue to shape his leadership today.
He now operates with a servant leadership approach—prioritizing people, empowering teams, and building with purpose. Lester also serves as a partner and visionary for Rubix Battery, helping guide strategy and growth across both organizations.
Josie Miller
Sales & Accounting, Rubix Battery
Josie Miller brings 30 years of experience in sales and accounting, grounded in integrity, transparency, and accountability. At Rubix, he ensures every customer interaction is clear, responsive, and built on trust. His focus is simple: reliable support that makes Rubix a dependable partner, not just a product.
Ryan Miller
Warehouse Operations & Service, Rubix Battery
Ryan Miller supports Rubix’s day-to-day warehouse operations, including inventory, order staging, and shipping. He also handles battery troubleshooting and repairs to keep systems reliable and ready for the field. With a detail-oriented, safety-first approach, Ryan helps keep everything accurate and on schedule.
Andy Schrock
Service Technician, Rubix Battery
Andy Schrock supports customer service and battery troubleshooting as a service technician at Rubix. His background includes construction, manufacturing, and technical service, giving him experience in delivering quality and reliability. Andy brings a hands-on, problem-solving approach to help keep systems running and customers supported.
David Yoder
Research & Development, Rubix Battery
David Yoder is part of the Research & Development team at Rubix. He focuses on advancing battery technology and energy solutions. With experience in solar, industrial automation, and electrical systems, he has a practical, hands-on approach to product development. His background helps drive reliable innovation across Rubix power systems.
The Rubix Guarantee
Expert Engineering
Our engineering solves problems. Every Rubix battery is designed for safety, efficiency, and long-term performance, using proven lithium technology and intelligent battery management systems.
We don’t use shortcuts. We engineer systems that are scalable, and ready for years of dependable use.
Premium Quality
Quality is our foundation. From components to construction, we build Rubix batteries with premium materials and rigorous standards. The result is consistent performance, long cycle life, and products that hold up under demanding conditions users put them through.
There are no compromises in our systems, so our customers experience fewer problems over time.
Friendly Service
We believe great technology should be backed by real people. Rubix offers knowledgeable, approachable, and personal support for installers and customers alike.
From larger concerns to small troubleshooting, our team is here to help—clearly and promptly.
Our Mission
Our mission is to deliver reliable, intelligent energy storage that empowers independence.
We aim to simplify energy systems, support the professionals who install them, and provide customers with long-lasting power they can trust, no matter where they use their power: at home, off-grid, or anywhere else dependable energy matters.
Our History
Rubix was born out of real-world frustration—and real-world experience.
2015
Lester, a professional logger, experiences repeated failures with a lead-acid winch battery in demanding field conditions. Frustrated by short lifespans and unreliable performance, he asks a simple but defining question:
“What actually makes the best battery?”
The answer: lithium.
2015–2019
With that insight, Lester founds MillerTech and later Life with MillerTech, focusing on lithium batteries engineered for real-world abuse, like logging, off-road, and demanding work environments.
At the same time, James is working in the solar industry. After acquiring Envirosol, he helps off-grid homeowners capture solar power for daily life. As his company grows, one issue becomes clear: the batteries available weren’t good enough.
To solve that problem, James starts ARK Battery, serving off-grid and Amish communities across the east-central United States. His customers depend on reliable power every day and can’t afford downtime.
Competitors With the Same Mission
For a time, Life with MillerTech and ARK Battery operate independently—and competitively. But both companies are driven by the same goal: long-lasting, durable lithium batteries built for off-grid living and hard use.
2020
Recognizing they could be stronger together, Lester and James join their experience, products, and values. Rubix is founded to solve those problems. The goal is clear: build better batteries by combining field experience with smart engineering. The result is a unified brand built on hands-on experience, installer partnerships, and premium lithium systems designed to scale.
2023
Rubix launches the Stack Series.
2025
Rubix launches the R-Series.