Energy tech · Mobile app

Your solar system is running perfectly. Or so the app says.

A speculative redesign of the Enpal customer app, focused on rebuilding financial trust through clarity, transparency, and plain-language savings visibility.

RoleUX Research & Design
IndustrySolar Energy Tech
Duration3 weeks
ResearchSecondary (reviews, forums)
Speculative redesign concept. No affiliation with Enpal. Research based on publicly available reviews and forums.
Savings screen — €3,240 saved in total, payback progress on trackHome screen — You saved €42 today, system working as expectedForecast screen — Projected €115 savings next month with Winter Efficiency context

Screens explored

HomeAlert stateSavingsPerformanceForecastNotificationsLanguage

The problem

Enpal customers couldn't verify their savings, couldn't tell if their system was underperforming, and couldn't trust the numbers the app showed them.

The insight

This isn't a data display problem. It's a trust problem. And for a company whose upsell strategy depends on satisfied customers, eroded trust has a direct commercial cost.

The approach

Six design solutions spanning financial clarity, performance confidence, proactive alerts, forecasting, notifications, and multilingual support for pan-European expansion.

01 · Context

Europe is going solar. Customers are going in blind.

Solar adoption is accelerating across Europe, driven by rising energy prices, REPowerEU policy targets, and falling panel costs. But accessibility created a new problem.

Enpal's model

Enpal offers solar PV, battery storage, EV chargers, and an energy monitoring app, on a subscription model. Customers don't own the panels. Enpal does. That shifts the relationship: customers are paying monthly for a promised outcome, not a purchased asset.

Why trust is Enpal's core product

A subscription customer who trusts the system stays, upgrades, and refers. A customer who suspects underperformance cancels and churns. Trust isn't a UX nice-to-have — it's directly tied to Enpal's upsell and retention performance.

2x

Solar energy production across Europe since 2019

600 GW

EU solar target by 2030 under REPowerEU

€20k+

Typical homeowner investment in a PV system

02 · Research

What real customers are saying

Research was conducted through App Store reviews, Play Store reviews, Reddit threads, and energy community forums. Three reviews became anchors, each representing a distinct layer of the same underlying trust failure.

All research is secondary, synthesised from publicly available customer reviews and community forums. No Enpal employees or customers were interviewed directly. Pain points were prioritised by frequency across sources.

Financial credibility

The app is showing feed-in tariffs of around €100 per day, even though 0 kWh were fed into the grid. How is that possible? Why can't the user enter their feed-in tariffs and simply multiply by the amount fed into the grid to get the correct amount?

App Store review · 5 users marked helpful

Money is shown without energy being sold. Cause and effect are broken. The user is proposing their own calculation: "tariff × kWh = money", because the app's logic is opaque. Users don't need a smarter algorithm. They need a transparent, traceable one. Understandability over sophistication.
System reliability

There are daily connection drops, and sometimes the Q2 fuse has to be reset several times a day to restart the Enpal box. Absolutely unacceptable. The app does what it's supposed to, when it actually works.

App Store review · 12 users marked helpful

The system violates the promise of automation. When automation fails silently and requires manual recovery, users lose confidence in both the hardware and the app, even when the interface itself is functional. The design opportunity: clear system state communication, transparent explanation during outages, and explicit "no action needed vs action required" messaging.
Daily friction

I constantly have to switch to "today," and it doesn't show me what the individual modules are generating or what the storage level has been over the last hour. And what's the "Enpal Life" button for? I can see my products there, but I can't click on them.

App Store review · 13 users marked helpful

The app is not aligned with the user's daily mental model. Critical data is incomplete or hard to access, and everyday interactions require unnecessary effort. Broken UI elements (buttons that don't work) actively undermine trust in the product's quality.

The user this redesign is for

HM

Hans Müller, 52

Homeowner, Berlin. Solar PV, battery storage, EV charger.

“I invested a lot in this system. I just want to quickly see that everything is working as it should.”

Checks the app daily

Often in the morning, to confirm the system ran well overnight.

Moderate tech comfort

Uses a smartphone daily but is not an energy engineer. Wants reassurance, not raw data.

Motivated by ROI

Wants to know their €20k investment is paying off, in euros, not kilowatts.

03 · Core insight

This is a trust problem, not a data problem

The data exists. The system monitors everything. The failure is in translation: from raw energy metrics to financial confidence.

“Enpal sells customers confidence. The current app fails to deliver it.”

The three reviews above represent three layers of the same problem: the user can't verify the numbers (financial credibility), can't rely on the system being available (system reliability), and finds the daily experience frustrating rather than reassuring (daily friction). Each layer erodes trust. And for a company whose upsell model depends on satisfied, trusting customers — trust is the product.

Current experience

"34.2 kWh produced"

Raw metric, no financial context

Graph with no benchmark

User can’t tell if output is good or bad

No system status

Silence feels like something is wrong

Redesigned experience

"You saved €42 today"

Euros first — the metric that matters

"Above your weekly average"

Instant context, no interpretation needed

"System working as expected"

Explicit reassurance removes anxiety

Based on patterns observed in App Store reviews. No access to the actual Enpal app codebase.

How might we

Restore user trust in an automated home energy system to enable confident energy and financial decisions?

04 · Scope

What this redesign solves, and what it doesn't

Transparent prioritisation. Hardware reliability and backend data accuracy are real problems — but they're not design problems. This redesign focuses on what the app can control.

In scope

  • Financial clarity: savings in euros, not kWh
  • Performance confidence: actual vs forecast output
  • Proactive alerts with plain-language explanations
  • Daily monitoring experience, reduced friction
  • Multilingual support for pan-European expansion

Out of scope

  • Hardware reliability (a network/infrastructure problem)
  • Backend data accuracy (a systems problem)
  • Installation and onboarding flows
  • Sales and quote experience
  • Advanced energy trading or tariff optimisation

05 · Competitive gap

Every app shows data. None closes the loop to trust.

A comparison of four players in the energy management space. The gap is consistent: technical data without financial context, and no connection back to the original sales promise.

Tibber DE

Smart energy + electricity provider

Real-time price optimisation
Consumption monitoring
Solar production tracking
Savings vs forecast
Financial trust layer
Plain-language summaries

Enpal (current)

Solar PV subscription provider

Solar production monitoring
Energy flow overview
Battery status
Savings vs forecast
Financial trust layer
Plain-language summaries

Tesla Energy

Premium solar + battery ecosystem

Solar production monitoring
Powerwall management
Time-based control
Savings vs forecast
Financial trust layer
Plain-language summaries

This redesign

Enpal: trust-first approach

Solar production monitoring
Energy flow overview
Battery status
Savings vs original forecast
Financial trust layer
Plain-language summaries

★ = differentiating features not available in compared apps. Tesla offers monetary savings estimates (Solar Value / Energy Value) but does not compare against original sales forecasts or payback timelines. Analysis based on publicly available app descriptions and reviews.

06 · Solutions

Six solutions, each rebuilding a layer of trust

Every design decision maps to a specific research finding. Expand “Design rationale” on any card to see the reasoning.

Home screen showing You saved €42 today
Solution 01

Home screen: lead with euros saved, not kilowatts produced

"€100 shown with 0 kWh fed in. How is that possible?"

The original app led with solar production in kWh, a metric most homeowners can't intuitively translate into financial terms. The redesigned Home screen opens with "You saved €42 today" as the primary statement, supported by a system health indicator ("System working as expected") and a plain-language energy flow summary. Technical metrics are present but secondary.

1Visibility of system status
Heuristic #1: Visibility of system status

Users should always know what is happening at a glance. The original app required users to interpret kWh figures to understand system health, putting the cognitive work on them. The redesign makes system status and financial outcome immediately visible without any interpretation required.

Key decision

Savings in euros as the hero metric, not production in kWh. Weather context (“Sunny today”) explains why today's numbers look the way they do — removing the anxiety of “is this normal?”

Savings screen with payback progress bar and monthly comparison
Solution 02

Savings: close the loop between the sales promise and reality

"Am I actually saving what I was promised?"

The savings screen directly answers the question every Enpal customer has but no current app answers: "Is my investment paying off as promised?" It shows total savings since installation, a payback progress bar (€3,240 of €19,800 paid back, on track), and a direct comparison: "Without solar: €187/mo. With solar: €31/mo." The sales forecast becomes a live benchmark, not a forgotten number from a brochure.

6Recognition over recall
Heuristic #6: Recognition over recall

Users shouldn't have to remember what they were promised at installation and compare it to what the app shows. The redesign makes the comparison explicit and persistent — the original sales forecast becomes a benchmark the app tracks against automatically.

Key decision

The payback progress bar is the most important element. It gives users a single, trackable answer to “was this worth it?” that doesn't require any calculation on their part.

Performance screen showing 94% system efficiency
Solution 03

Performance: show expected vs actual, in plain English

"Can't see if my system is actually working correctly"

Instead of showing raw output figures, the performance screen opens with "Everything is running optimally" and a single efficiency score: 94% of expected output, within normal range. A 7-day actual vs expected bar chart shows the trend. Component status (panels, battery, grid) is shown with plain-language descriptions, not just green dots. The default state is explicitly reassuring — users aren't left to wonder if a number is good or bad.

4Consistency and standards
Heuristic #4: Consistency and standards

Users shouldn't have to interpret what a number means — “94% efficiency” only tells them something if there's a consistent reference point. The redesign establishes “expected output” as that reference, so every reading is automatically contextualised against the forecast the system was sold on.

Key decision

The headline is always a verdict, not a metric. “Everything is running optimally” — not “94 kWh.” The number supports the verdict; the verdict doesn't require interpretation.

Home screen — green state, €42 saved
Home screen — amber state, €28 saved
Home screen — coral state, €12 saved
Solution 04

Alert state: a three-tier model that communicates severity through savings impact

"I have to reset the hardware myself. Unacceptable."

The System Health card uses a traffic-light model with three distinct states. Green: "System working as expected" with a checkmark — daily savings shown as €42. Amber: "Battery charging slower than expected. Enpal is monitoring." with a warning triangle — savings reduced to €28. Coral: "Inverter issue detected. Our team is responding. Tap to contact support." with an alert circle — savings reduced to €12. The dashboard layout stays identical across all three states; only the card colour, messaging, and savings figures change. This prevents layout shift and preserves spatial memory.

5Error prevention
Heuristic #5: Error prevention and recovery

When errors occur, users need to know three things: what happened, whether it affects their savings, and whether they need to do anything. Each alert tier answers all three in one glance. Savings figures differentiate per state (€42 / €28 / €12) so users understand the financial impact of an issue — not just its existence.

Key decision

Coral (#ffd0d0) was chosen over alert red (#ff0000) for the critical state. Red feels alarming and erodes trust — precisely the opposite of what the app should do when a homeowner sees an alert on a system they paid €20k for. Coral communicates urgency without panic. And “No action is needed from you” on the amber state removes anxiety at exactly the moment it would otherwise spike.

Forecast screen showing projected €115 savings
Solution 05

Forecast: show what next month will look like before it happens

"I never know if winter months are costing me more than expected"

The Forecast screen projects next month's estimated savings (€115), contextualised with seasonal efficiency factors. Winter months naturally produce less solar energy — instead of letting users discover this through a confusing dip in their savings, the app explains it upfront. A CO₂ offset tracker adds environmental impact alongside financial data, giving users a second dimension of value from their system.

1Visibility of system status
Heuristic #1: Visibility of system status

Forward-looking data reduces the anxiety gap between monthly bills. Users who can see projected savings don't need to wonder whether their system is underperforming during winter — the app tells them before they have to ask. This is visibility extended into the future, not just the present.

Key decision

Pairing financial projection with CO₂ offset tracking. Users who aren't motivated by money alone can see their environmental impact — and users who are focused on ROI get a forward-looking number that keeps them engaged between bills.

Notifications — 3 items
Notifications — 2 items
Notifications — 1 item
Notifications — All caught up!
Solution 06

Notifications: keep users informed without overwhelming them

"I missed an alert because I didn't check the app that day"

A bell icon with a count badge (1 or 3 depending on severity state) signals unread alerts. Notification cards use icon circle colours to communicate severity: amber for attention-needed items, green for positive confirmations. Users can dismiss individual notifications or tap "Mark all as read" to clear the list. The dismiss flow progresses naturally: 3 items, 2 items, 1 item, then an empty state reading "All caught up! No new notifications. Your system is running smoothly."

3User control and freedom
Heuristic #3: User control and freedom

Users need to control what they've seen. The dismiss flow gives them agency over their notification list, while the system communicates proactively so users don't need to manually check for issues. The System Health card on the Home screen is tappable and navigates directly to Notifications.

Key decision

The empty state is deliberately reassuring: “All caught up!” closes the loop. It tells users there's genuinely nothing to worry about — not that the system has stopped communicating. Severity is communicated through icon circle colour, not left border bars (which clipped against rounded corners in testing).

See all six solutions in the interactive prototypeOpen Figma prototype

07 · Design trade-offs

Every decision had a reason. Here are five.

Design is choosing. These are the choices that shaped the prototype — each one a deliberate trade-off, not a default.

Green state — €42 saved
Green · €42
Amber state — €28 saved
Amber · €28
Coral state — €12 saved
Coral · €12

Same layout, same position, same components — only the colour, message, and savings figure change.

Coral over red for critical alerts

Red (#ff0000) feels alarming and erodes trust at exactly the moment the app needs to build it. Coral (#ffd0d0) communicates urgency without panic — critical for a user staring at an alert on a system they paid €20k for.

Savings change per alert state: €42 → €28 → €12

If the savings figure stayed at €42 during a critical alert, the user sees conflicting signals — the card says something is wrong, but the number says everything is fine. Differentiated figures make severity financially tangible.

Two-factor authentication removed

The persona is 52 and moderately tech-comfortable. 2FA adds friction that outweighs its security benefit for this audience. Biometric login (FaceID/TouchID) was kept — it’s easy to operate. This is a deliberate simplification, not an oversight.

Notification severity via icon colour, not left borders

Left border bars were tested first but clipped against the card’s rounded corners, creating a visual artefact. Icon circle colours (amber for warnings, green for positive) communicate severity cleanly within the card’s existing shape.

Help moved from Settings footer to dedicated page

Help was buried at the bottom of My Account, past four sections of settings. For a user who needs support, that’s four scrolls too many. The ? icon now appears on all six main screens, and Help & Support is also in the hamburger menu — two paths to the same destination.

Process note: A full Nielsen Norman 10-heuristic evaluation was conducted across all 15 screens before finalising the prototype. These trade-offs emerged from that process — alongside fixes for navbar variant errors, jargon simplification, and visual consistency issues across alert and notification states.

08 · Interaction patterns

Two patterns designed for a 52-year-old homeowner

Both additions came directly from the persona. Hans is moderately tech-comfortable — explicit, labeled access always beats implicit navigation patterns.

Home screen with hamburger icon highlighted
Menu page with 6 labeled items

Hamburger menu

The profile photo was originally the only entry point to My Account — too implicit for older users. The hamburger menu provides explicit, labeled access to all six secondary features: My Account, Notifications, Help & Support, Language & Currency, About Enpal, and Log Out.

Both the hamburger menu and shortcut icons (? and bell) remain. The menu is a safety net. The icons are accelerators. This is Heuristic #7: flexibility and efficiency of use.

Home screen with ? icon highlighted
or
Menu with Help & Support row highlighted
Help & Support page with 4 channels

Help discoverability

Help was originally buried at the bottom of Settings, requiring users to scroll past four sections to find it. It now has a dedicated Help & Support page accessible via a ? icon present on all six main screens and via the hamburger menu.

Four clear channels: Chat with Support (AI chatbot), Call Support, Email Support, and System Guide. Each CTA names the channel — no ambiguous wording. This is Heuristic #10: help and documentation.

09 · Multilingual support

Trust doesn't translate automatically

Pan-European expansion requires more than translated strings. Financial terminology, number formats, and currency conventions differ across markets. The language selector is a strategic feature, not just a settings option.

Enpal's expansion beyond Germany into France, Spain, Italy, and the UK requires the app to feel native in each market, not just translated. The Settings screen supports all five target languages alongside a currency display toggle (EUR, CHF, GBP), so financial data always appears in the format that feels natural to each user. German is the primary market; English supports UK expansion, French/Spanish/Italian unlock pan-European reach, and CHF support extends to Switzerland — whose three official languages (German, French, Italian) are already in the dropdown.

My Account · Settings sections

Personal Details section of My Account — Hans Müller's profile data
Localization section — App Language (English) and Currency Display toggle (EUR, CHF, GBP)

Localization is where the multilingual story actually lives — five language options plus EUR / CHF / GBP currency display, both inside the same My Account profile page.

Business case: Enpal's upsell model depends on trust. A British customer seeing EUR amounts when they expect GBP, or a French customer reading savings data in German, faces an immediate trust barrier before the content has even had a chance to reassure them. Language and currency support is trust infrastructure, not a UI addition.

10 · Learnings

What this project taught me

Two things I'd carry directly into a real product team.

01

UX and business goals aren't just aligned here — they're the same thing.

I started thinking this was a data display problem. The research showed it was a financial trust problem — and financial trust is literally what Enpal's upsell model runs on. When the UX goal and the business goal are the same variable, every design decision has direct commercial weight. That changes how you prioritise.

02

Secondary research can be as specific as primary — if you synthesise well.

Three App Store reviews, each cited by multiple users as helpful, gave clearer design direction than a generic interview guide would have. The specificity was already in the data. The job was to recognise which complaints were patterns, not outliers, and to follow the emotional thread underneath them.

Explore the full prototype

All 15 screens across 6 solutions, 3 alert states, and the full notification dismiss flow.

Open Figma prototype

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