Independent solar-monitoring concept

Step into the solar side with confidence.

With the share of surveyed German homeowners who already have or plan to install solar potentially reaching 65% by 2029, I explored how Enpal could make system performance understandable, actionable, and trustworthy.

ResearchSecondary synthesis · no customer interviews
Deliverable15-screen interaction model
Personal project with no affiliation or access to Enpal's customers, calculations, product data, or production UI.
Home screen showing daily savings and system status
Home
Savings screen comparing performance with forecast
Savings
Forecast screen showing projected monthly savings
Forecast

Signal

Precise financial values lose credibility when their inputs are hidden.

Focus

Traceable savings, forecast comparison, and explicit system states.

Boundary

The interface cannot repair hardware, backend, or calculation accuracy.

Status

Directional hypotheses awaiting customer and domain validation.

01 · Evidence to insight

The evidence points to clearer verdicts—not more telemetry.

Secondary research combined representative German homeowner data, peer-reviewed PV research, cross-market monitoring behavior, and three App Store reviews. No primary interviews were conducted.

01

The audience is broadening

German adoption data suggests the audience increasingly includes homeowners with moderate technical comfort. The interface should not assume energy expertise.

02

Financial figures need visible inputs

A precise euro figure loses credibility when users cannot inspect its tariff, energy inputs, freshness, or missing data.

03

Reviews suggest anomaly states need more context

During an issue, customers may not know what changed, whether savings are affected, or whether action is required.

Representative evidence

“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?”

App Store review · illustrates calculation opacity

Core insight

Design hypothesis: financial numbers may feel more credible when their inputs and changes are visible.

The opportunity is narrower than “replace kWh with euros”: expose the calculation, compare it with a meaningful forecast, and communicate uncertainty during anomalies.

Focus

  • Savings inputs, formula, freshness, and confidence
  • Actual performance compared with forecast
  • Plain-language alerts and support handoff

Not addressed

  • Hardware reliability or backend accuracy
  • Installation, sales, or tariff optimization
  • Measured product or business impact

System reliability

Evidence: A review described daily connection drops and repeated hardware resets.

Design implication: The interface should distinguish monitoring, action required, and support ownership without diagnosing infrastructure it cannot observe.

Daily friction

Evidence: A review described incomplete module data, repeated view switching, and unclear controls.

Design implication: The daily experience should lead with a verdict and make important destinations explicit.

02 · Three design decisions

Three decisions define the concept.

The full prototype contains 15 screens. The primary story is concentrated into the three decisions below; the remaining screens support those decisions rather than competing with them.

Decision 01

Expose how financial outcomes are calculated

Home screen with daily savings and healthy system status
Daily verdict
Savings screen with payback progress and monthly comparison
Savings trace
Performance screen comparing actual and expected generation
Actual vs expected
Forecast screen explaining projected winter savings
Forward context

Evidence

A review questioned a precise value whose energy inputs and tariff assumptions were invisible.

Decision

Let users trace savings to production, tariffs, freshness, and the original forecast.

Trade-off

Payback appears only where the contract supports it; all values are illustrative.

Next test

Can customers explain the figure and recognise stale or seasonal data?

The headline is a verdict rather than an isolated metric. Home answers “Is everything working?”; Savings connects performance with the customer's agreement; Performance explains actual versus expected output; Forecast prepares users for seasonal change.

This applies visibility of system status and recognition over recall without pretending that interface clarity can repair an inaccurate calculation.

Decision 02

Explain anomalies and the next action

Green system health state
Working normally
Amber system health state under monitoring
Being monitored
Critical system health state with support action
Action required
Notification center with three status messages
Notification trail

Evidence

A review described connection failures without clear ownership or next action.

Decision

Use one stable health card with label, explanation, urgency, and next action.

Trade-off

Severity cannot depend on color; savings must come from measured intervals.

Next test

Can users interpret severity and choose the correct next action?

The layout stays fixed across states to preserve spatial memory. Notifications retain the history, allow individual dismissal, and close with a reassuring empty state.

“No action needed” is only appropriate when monitoring and support policy genuinely justify it. Critical states must remain explicit even when the visual language avoids alarmist red.

Decision 03

Give help and secondary actions explicit entry points

Home screen with the hamburger menu highlighted
Explicit entry
Menu with labeled secondary destinations
Labeled safety net
Help and Support page with four contact channels
Support channels

Evidence

Implicit profile navigation and buried support are difficult to discover under stress.

Decision

Keep shortcut icons, then add a labeled menu and a second route to support.

Trade-off

Intentional redundancy adds chrome in exchange for clearer recovery paths.

Next test

Measure first-click success across age and technical-comfort groups.

The menu names My Account, Notifications, Help & Support, Language & Currency, About Enpal, and Log Out. Shortcut icons remain available for frequent actions.

Each support CTA names its channel—chat, call, email, or guide—so the destination is clear before selection.

03 · Assumption audit

The concept improved when its riskiest assumptions were challenged.

A structured review exposed three high-risk assumptions. The useful outcome was not more polish; it was narrower claims and safer states.

Calculation integrity

Risk found

Alert severity appeared to directly change the savings figure.

Revision

Financial impact now requires measured intervals, tariffs, downtime, and a confidence state.

Secure access

Risk found

Two-factor authentication was removed based on assumptions about older users.

Revision

The concept preserves account protection and explores biometrics, passkeys, recovery, and risk-based access.

Accessible severity

Risk found

Color carried too much responsibility for communicating status.

Revision

Icon, label, explanation, urgency, and action reinforce every state; color is supplementary.

  • • Corrected the account-page navbar to use a neutral tab state.
  • • Replaced jargon and gamified labels with plain-language status.
  • • Added reassurance and action copy to every alert state.
  • • Added individual dismiss, mark-all-read, and a clear empty state.
  • • Moved Help & Support out of the settings footer.

Still unvalidated

No customer testing, internal product access, production data, calculation audit, or measured business impact. The concept is a set of hypotheses ready for validation—not evidence of an Enpal product outcome.

04 · Supporting work

The supporting work remains available without blocking the story.

Localization, the directional market scan, and detailed sources are useful evidence, but they are secondary to the three product decisions above.

The prototype explored five languages and three currencies. With no validated expansion brief, this remains a UI exploration—not a core solution or launch recommendation.

Personal details section in My Account
Personal details
Language and currency controls in My Account
Language & currency

Public descriptions of Tibber, Enpal, and Tesla Energy informed the opportunity. This is a dated directional scan, not an exhaustive feature audit.

Tibber DE

Smart energy

Price optimization
Consumption monitoring
Savings vs forecast

Enpal

Solar customer app

Production and flow
Earnings and savings
Inspectable forecast comparison

Tesla Energy

Solar + battery

Energy monitoring
Monetary estimates
Original forecast comparison

Concept

Concept focus

Production and flow
Traceable calculation
Actual vs forecast
  • • Initiative Klimaneutrales Deutschland (2025): representative survey of 4,000+ German homeowners.
  • • Wittenberg & Matthies (2016): German residential solar-household research.
  • • Enact (2022): 482 verified US solar owners, used only as cross-market corroboration.
  • • Clean Energy Wire, Fraunhofer ISE, BSW-Solar, and KfW for German market context.
  • • Three App Store reviews used as illustrative owner voices.

05 · Reflection

The concept became more defensible when it focused on traceability—not simply replacing kWh with euros.

What changed

The concept moved from a euros-first interface toward an inspectable relationship between energy, tariffs, forecasts, and confidence.

Limitation

Secondary research can frame hypotheses, but it cannot establish Enpal customer needs, calculation accuracy, or product impact.

Next validation

Test calculation drill-down, missing-data states, contract-specific views, severity comprehension, and support handoff with customers and domain experts.

Explore the full interaction model

15 screens, three system-health states, and the complete notification dismiss flow.

Open Figma prototype