Background
Having previously worked closely with some of the sonnen team during my time on the Shell Energy Assistant, I was invited to join a small research and discovery sprint. I led the end-to-end design and research effort; from competitor analysis and concept creation through to prototyping, testing, and synthesis.
Team SetupThe core team consisted of myself and a Product Owner, with regular alignment sessions with sonnen's key stakeholders.
With a new EU mandate on the horizon requiring energy providers to adopt dynamic tariffs by 2024, sonnen needed to test how customers might discover, understand, and integrate a dynamic energy tariff into their daily routines.
Deliverables included- A marketing page on sonnen's website to introduce the tariff
- An exploration of how the tariff would integrate into sonnen's app
Planning the Sprint
This was a 5-week sprint that aimed to design, test, and derive key learnings within a condensed timeframe.
The sprint was designed to move fast, with clear weekly deliverables across research, design, and testing. Activities included competitor analysis, market research, personas, UI design, prototyping, and moderated and unmoderated user testing.
- Research gathering
- Core requirements
- Marketing page design
- Preliminary app flow and designs
- User testing and evaluation of marketing page
- Refinement of app functionality
- High fidelity prototype creation
- Unmoderated app user testing
- Assimilation of results
- Stakeholder presentations to share findings and insights
Understanding sonnen's User Groups
One of my first tasks alongside the Product Owner was defining who we were actually designing for. Targeting sonnen's existing battery owners seemed like an obvious starting point, but after light research and a strategic conversation, we moved away from that. The added complexity of self-energy production, combined with our tight timeline, pointed us in a different direction.
We made the call to focus on prospective customers instead. This gave us a cleaner scope, a more accessible entry point to test the dynamic tariff proposition.
Communicating the Proposition Clearly
Dynamic tariffs are fundamentally different from traditional fixed or off-peak plans. So, the challenge wasn't just explaining the tariff - it was also making it feel useful, trustworthy, and worth switching for.
Market & Competitor Research
I explored how energy companies present tariffs, focusing on those already experimenting with flexible pricing, including websites and live apps with active users. Ostrom and Octopus Energy stood out as strong examples.
Combined with insights from sonnen's product teams, this shaped a clear picture of what the marketing page needed:
- Intro to the tariff
- Key benefits and price comparisons
- Customer stories
- Educative content - how a dynamic tariff works
Marketing Page Wireframes
Based on these insights, I designed some page concepts that included tariff comparison, educational explanation, and price analysis. The aim was to understand which information mattered most to users, what captured their attention, and what might drive conversion. Here is the high fidelity wireframe that we tested.
Reworking the App for Testing
The existing sonnen app was built entirely around battery ownership and energy production data so it was going to get convoluted when it came to testing on prospective customers. So we decided to create a new, utility-centric app experience, just to test the dynamic pricing feature.
The redesigned dashboard focused on:
- Daily energy usage
- Price forecasts for the next three days
- Tile-based access to key features
I created high fidelity wireframes for this and tested them in moderated sessions.
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High fidelity wireframes tested on user groups during moderated interviews
What We Learned
Testing was split into two phases: moderated testing of the marketing page, followed by unmoderated testing of the app onboarding and core experience. Participants were recruited in Germany and Australia and met strict criteria: homeowners, energy decision-makers, and no existing PV systems.
Results revealed that while users struggled to grasp dynamic pricing on the marketing page alone, everything clicked once they interacted with pricing forecasts and usage data inside the app. Seeing prices change in context transformed abstract pricing into something practical and actionable.
Users clearly recognised the long-term potential of dynamic tariffs, especially when paired with EVs or solar
Price transparency was critical — users wanted simple, upfront comparisons
The app experience significantly improved understanding and engagement
of users said price tracking in the app would motivate them to adopt a dynamic tariff and become sonnen customers
The Moments That Mattered
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Static content can only go so far This sprint reinforced how difficult it can be to explain complex pricing models through static marketing alone, and just how powerful interactive tools can be in bridging that gap. Testing marketing and product experiences together proved to be the right approach.
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Closing with confidence To close the sprint, I condensed all findings into a clear, stakeholder-friendly deck and presented a refined version of the marketing page informed by testing insights. The work was recieved very positively internally and used as a foundation for the full product rollout planned for 2024.
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What would come next With more time, I'd explore deeper personalisation and longer-term usage patterns: particularly how trust builds over repeated exposure to dynamic pricing.
