CASE STUDY - HMI /hardware interface design
Ara Human-Machine Interface Redesign
dcbel builds a smart home energy system that manages solar, electric vehicle battery, backup energy storage, and grid power from a single wall-mounted unit. Its interface failed during real internal field testing during a blackout. I led the redesign, and it shipped on time.
My Role
Senior Product Designer
Tools
Figma
Timeline
2 months
Oct - Nov 2025
Human-machine interface design
Field research
Design strategy
Moderated usability testing
Design systems
C-suite alignment
Scope negotiation
01 -
Context: designing without inherited bias
I was deliberately kept away from the existing interface so I wouldn't inherit its assumptions.
Instead of reviewing the existing HMI design, I was tasked with building a new concept from scratch, grounded in in-lab heuristic evaluation. For two months after I joined the company, I iterated on wireframes and journeys for new users.
As a new product category in the market, there were no category conventions to borrow from. I had to map its usability to known behaviours from industries like EVs and power backup.
how might we
Can you make a home energy interface intuitive for non-technical users through visual design, without rebuilding the underlying platform?
Increased velocity by 15x
Resolved a multi-month blocker on the user notification framework and restored executive confidence.
dcbel's first design system
Built the company's first HMI design system from scratch with tokens, typography, and complete component library that works for the engineering team.
I'd love to share my design process but the details of this project is private. To view the complete project, please use the password I provided or feel free to contact me.
What you will unlock -
The catalyst: when the design failed a real field test
Strategy: from revolution to evolution
Redesign
Redesign
Design system: the company's first
Unlock
08 -
Lessons learned
LESSON 01
The best design is the one that can ship
The right strategy for this project was a targeted evolution that respected technical debt and preserved the launch date while still meaningfully improving usability. Quality is impact achievable within real constraints, not visions.
LESSON 02
Simplicity is the ultimate empathy
We designed for homes with people who didn't understand technical jargon. They didn't need technically informative screens. They needed simple designs and metrics they could easily understand.
LESSON 03
Trust is built through alignment