Viessmann: HEMS Financial Analysis

The client, a renowned German manufacturer in the heating and refrigeration industries, sought to enhance their existing SaaS-based Home Energy Management System (HEMS) app. The goal was to introduce a new feature enabling photovoltaic (PV) system owners to efficiently track and analyse key performance and financial metrics — empowering users to make smarter, data-informed decisions about their home energy usage.

Viessmann ViCare App Reference:
https://www.viessmann.co.uk/en/products/control-system-and-connectivity/vicare-app.html

The Problem

PV system owners currently lack a user-friendly tool to monitor the financial performance of their systems. This gap makes it difficult to optimise energy usage or maximise returns, limiting users’ ability to make informed, data-driven decisions.

Objective

Within 36 weeks, design a comprehensive finance feature within the HEMS app that goes beyond tracking energy consumption and billing. The feature should enable PV owners to monitor savings, earnings, and other key financial metrics—helping users to make smarter energy management decisions.


My contribution

I contributed to a Financial Analysis feature in Viessmann’s SaaS-based energy platform for PV system owners. Working with two UX designers, I conducted research and mini interviews to identify user pain points, followed by A/B testing to compare early concepts. We refined design concepts and wireframes based on feedback, resulting in a clearer, more user-friendly experience aligned with the platform’s goals.

EMPATHISE

EMPATHISE

What PV owners think ?

What PV owners think ?

In addition to the research provided by the client, I conducted secondary research and mini interviews with five PV owners to better understand their behaviour and preferences in managing system finances.

In addition to the research provided by the client, I conducted secondary research and mini interviews with five PV owners to better understand their behaviour and preferences in managing system finances.

The desktop research sat PV users:

The desktop research sat PV users:

Tend to have higher environmental awareness, and make more rational economic decisions.

Tend to have higher environmental awareness, and make more rational economic decisions.

Studies show mixed findings on PV adoption by income level—wealthier households invest more easily, while lower-income groups are driven by energy savings.

Studies show mixed findings on PV adoption by income level—wealthier households invest more easily, while lower-income groups are driven by energy savings.

Most long-term PV users are middle-aged or older, but younger adoption is rising.

Most long-term PV users are middle-aged or older, but younger adoption is rising.

PV users in mini interviews say

PV users in mini interviews say

They use a variety of tools such as budgeting apps, web dashboards, and customised spreadsheets.

They use a variety of tools such as budgeting apps, web dashboards, and customised spreadsheets.

High Satisfaction with Spreadsheets: The majority expressed highest satisfaction with using spreadsheets due to their flexibility, customisability, and the control they offer over financial tracking.

High Satisfaction with Spreadsheets: The majority expressed highest satisfaction with using spreadsheets due to their flexibility, customisability, and the control they offer over financial tracking.

Competitor Research

Competitor Research

Our team began by researching energy tracking apps across different regions—including the US, Australia, Europe, and Asia—to understand the maturity of tools available in the market. We then narrowed our focus to apps that specifically offer both energy and finance monitoring features.


Key Findings

  • Most apps prioritise energy tracking, such as kWh consumed or generated, rather than financial insights.

  • Financial monitoring features appeared mainly in apps from Australia and the UK.

  • Where available, financial data was usually limited to total bills, costs, and basic analysis related to consumption and feed-in tariffs.

Our team began by researching energy tracking apps across different regions—including the US, Australia, Europe, and Asia—to understand the maturity of tools available in the market. We then narrowed our focus to apps that specifically offer both energy and finance monitoring features.


Key Findings

  • Most apps prioritise energy tracking, such as kWh consumed or generated, rather than financial insights.

  • Financial monitoring features appeared mainly in apps from Australia and the UK.

  • Where available, financial data was usually limited to total bills, costs, and basic analysis related to consumption and feed-in tariffs.

DEFINE

DEFINE

Pain points

Pain points

Based on research into existing PV tracking apps and user insights, several key challenges emerged regarding financial analysis features:

Understanding Metrics: Many users, especially younger or new PV owners, struggle to interpret key metrics on energy production, consumption, and financial performance.

Lack of Financial Context: Most tools display data in kWh only, without converting it into monetary terms (e.g. Euros), leaving users to estimate financial impact themselves.

No Real-Time Data: Limited access to real-time updates makes it harder for users to track system performance effectively.


No Real-Time Data: Limited access to real-time updates makes it harder for users to track system performance effectively.

Missed Opportunities: These gaps prevent users from optimising energy usage and maximising financial returns.

IDEATE/DESIGN

IDEATE/DESIGN

Two Wireframe Concepts

Two Wireframe Concepts

After generating numerous ideas and creating various design sketches, we finalised two design options for the Voltisight Financial Analysis feature. Both concepts incorporate visuals to effectively break down key metrics such as kilowatt-hours (kWh), monetary figures, and percentages. This visual approach is designed to enhance comprehensibility for both new PV system adopters and experienced PV app users, ensuring that the data is accessible and easy to understand.

After generating numerous ideas and creating various design sketches, we finalised two design options for the Voltisight Financial Analysis feature. Both concepts incorporate visuals to effectively break down key metrics such as kilowatt-hours (kWh), monetary figures, and percentages. This visual approach is designed to enhance comprehensibility for both new PV system adopters and experienced PV app users, ensuring that the data is accessible and easy to understand.

Concept 1 Overview:

Concept 1 Overview:

Concept 1 Overview:

  • Show visualisation overlapped charts: Features overlapped bar charts showing Costs and Earnings in Euros, enabling users to immediately compare how their PV earnings to their consumption costs.

  • Show visualisation overlapped charts: Features overlapped bar charts showing Costs and Earnings in Euros, enabling users to immediately compare how their PV earnings to their consumption costs.

  • Show visualisation overlapped charts: Features overlapped bar charts showing Costs and Earnings in Euros, enabling users to immediately compare how their PV earnings to their consumption costs.

  • Detailed View: Further down, users find Costs and Earnings displayed in separate tabs with an overall percentage chart that emphasises the accountability of their consumption costs.

  • Detailed View: Further down, users find Costs and Earnings displayed in separate tabs with an overall percentage chart that emphasises the accountability of their consumption costs.

  • Detailed View: Further down, users find Costs and Earnings displayed in separate tabs with an overall percentage chart that emphasises the accountability of their consumption costs.

Concept 2 Overview:

Concept 2 Overview:

Concept 2 Overview:

  • Show direct Financial Benefit: Directly illustrates the financial benefits of owning a PV system, such as showing that users would have paid €68.40 more without their PV system at home.

  • Show direct Financial Benefit: Directly illustrates the financial benefits of owning a PV system, such as showing that users would have paid €68.40 more without their PV system at home.

  • Show direct Financial Benefit: Directly illustrates the financial benefits of owning a PV system, such as showing that users would have paid €68.40 more without their PV system at home.

  • Detailed view: Unlike Concept 1, which uses separate tabs, this concept integrates all key financial metrics into a set of bar charts, offering a consolidated view of the data.

  • Detailed view: Unlike Concept 1, which uses separate tabs, this concept integrates all key financial metrics into a set of bar charts, offering a consolidated view of the data.

  • Detailed view: Unlike Concept 1, which uses separate tabs, this concept integrates all key financial metrics into a set of bar charts, offering a consolidated view of the data.

Time Frame

The time frame function was modified to be more prominent and fixed during scrolling to accommodate elderly users better. This update allows users to adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, to address issues with real-time data accuracy, users can now view data updates every 15 minutes on the app.

Removed summary bar charts

The summary bar chart, which users found less useful and might cause accessibility issues, was removed. This change simplifies the interface and focuses on the data breakdowns that users find most valuable.

Included filter function

A new filter function was introduced, enabling users to select and view bar charts for specific categories such as All, Costs, Savings, and Earnings. This feature allow users to customise data views, display information based on their specific needs.

(Almost) Real-time data!

Users now can adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, the client also gave feedback on real-time data. The system could not offer immediate data updates on the app, but users can view data updates every 15 minutes on the app, which provides accuracy.

PROTOTYPE / TEST

PROTOTYE &TEST

PROTOTYPE

& TEST

Comparison Usability Testing & Affinity Map

Comparison Usability Testing

& Affinity Map

Five PV owners from different countries were recruited by a third-party to participate in an online interview using Google Meet. Prototypes were tested on Maze and Figma, with feedback collected through Google Forms. The aim was to determine which design concept was preferred by PV owners and gauge their understanding of the data and terminology used. The focus was on user interaction and comprehension rather than direct A/B testing, thus it was termed "Comparison Usability Testing".

Five PV owners from different countries were recruited by a third-party to participate in an online interview using Google Meet. Prototypes were tested on Maze and Figma, with feedback collected through Google Forms. The aim was to determine which design concept was preferred by PV owners and gauge their understanding of the data and terminology used. The focus was on user interaction and comprehension rather than direct A/B testing, thus it was termed "Comparison Usability Testing".

User Interview Process Overview

Identify users’ preferred methods for financial tracking.

Present concept designs and gather feedback on feature clarity and suggestions.

Observe user behaviour while interacting with Concept 1 and Concept 2.

Collect user preferences and comments to determine the more effective concept.

Affinity Map

After the interviews, a digital affinity map was created to categorise user feedback. Responses were colour-coded into three categories based on ease of understanding: "Easy to Understand" (Green), "Somehow Easy But Unclear" (Yellow), and "Difficult to Understand" (Red).

Report

Report

  • Testing showed a preference for Concept 2. All users found the monetary data breakdown in Concept 2 easier to understand compared to the overlapped bar charts in Concept 1.

  • Users preferred monetary figures paired with kWh units over percentages.

  • While real-time data tracking was preferred, older users found closely stacked, overlapping bar charts challenging.

  • A colour-blind user highlighted issues with the red/green colour combination in Concept 1, prompting reconsideration of colour choices to accommodate accessibility.

  • Testing showed a preference for Concept 2. All users found the monetary data breakdown in Concept 2 easier to understand compared to the overlapped bar charts in Concept 1.

  • Users preferred monetary figures paired with kWh units over percentages.

  • While real-time data tracking was preferred, older users found closely stacked, overlapping bar charts challenging.

  • A colour-blind user highlighted issues with the red/green colour combination in Concept 1, prompting reconsideration of colour choices to accommodate accessibility.

POST-TESTING

POST-TESTING

Adjustments to improve

Adjustments to improve

Based on the feedback received, the following improvements were implemented to enhance the user experience and functionality to meet the customer’s expectation

Based on the feedback received, the following improvements were implemented to enhance the user experience and functionality to meet the customer’s expectation

Time Frame

Time Frame

The time frame function was modified to be more prominent and fixed during scrolling to accommodate elderly users better. This update allows users to adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, to address issues with real-time data accuracy, users can now view data updates every 15 minutes on the app.

The time frame function was modified to be more prominent and fixed during scrolling to accommodate elderly users better. This update allows users to adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, to address issues with real-time data accuracy, users can now view data updates every 15 minutes on the app.

Removed summary bar charts

Removed summary bar charts

The summary bar chart, which users found less useful and might cause accessibility issues, was removed. This change simplifies the interface and focuses on the data breakdowns that users find most valuable.

The summary bar chart, which users found less useful and might cause accessibility issues, was removed. This change simplifies the interface and focuses on the data breakdowns that users find most valuable.

Included filter function

Included filter function

A new filter function was introduced, enabling users to select and view bar charts for specific categories such as All, Costs, Savings, and Earnings. This feature allow users to customise data views, display information based on their specific needs.

A new filter function was introduced, enabling users to select and view bar charts for specific categories such as All, Costs, Savings, and Earnings. This feature allow users to customise data views, display information based on their specific needs.

(Almost) Real-time data!

(Almost) Real-time data!

Users now can adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, the client also gave feedback on real-time data. The system could not offer immediate data updates on the app, but users can view data updates every 15 minutes on the app, which provides accuracy.

Users now can adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, the client also gave feedback on real-time data. The system could not offer immediate data updates on the app, but users can view data updates every 15 minutes on the app, which provides accuracy.

Removed summary bar charts

Removed summary bar charts

The summary bar chart, which users found less useful and might cause accessibility issues, was removed. This change simplifies the interface and focuses on the data breakdowns that users find most valuable.

The summary bar chart, which users found less useful and might cause accessibility issues, was removed. This change simplifies the interface and focuses on the data breakdowns that users find most valuable.

Included filter function

Included filter function

A new filter function was introduced, enabling users to select and view bar charts for specific categories such as All, Costs, Savings, and Earnings. This feature allow users to customise data views, display information based on their specific needs.

A new filter function was introduced, enabling users to select and view bar charts for specific categories such as All, Costs, Savings, and Earnings. This feature allow users to customise data views, display information based on their specific needs.

(Almost) Real-time data!

(Almost) Real-time data!

Users now can adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, the client also gave feedback on real-time data. The system could not offer immediate data updates on the app, but users can view data updates every 15 minutes on the app, which provides accuracy.

Users now can adjust the financial analysis to their preferred view (yearly, monthly, daily), moving away from the default 'day view' and its associated dense, sticky bar charts.


Additionally, the client also gave feedback on real-time data. The system could not offer immediate data updates on the app, but users can view data updates every 15 minutes on the app, which provides accuracy.

REFLECTION

REFLECTION

What I have learned

What I have learned

Joining the project halfway brought some initial challenges, as I needed to pick up existing research based on earlier insights, did research and testing again to confirm previous results. I was fortunate to have a great UX design team, and I learned valuable knowledge from the UX lead on how to manage and maintain harmony between different teams with varying perspectives.

The experience was very rewarding, as I learned a lot about the specific user group. Interviewing super-users gave us useful insights that helped us design a more user-focused app. This also matched the project’s goal of raising environmental awareness, making the work both meaningful and impactful.

Joining the project halfway brought some initial challenges, as I needed to pick up existing research based on earlier insights, did research and testing again to confirm previous results. I was fortunate to have a great UX design team, and I learned valuable knowledge from the UX lead on how to manage and maintain harmony between different teams with varying perspectives.

The experience was very rewarding, as I learned a lot about the specific user group. Interviewing super-users gave us useful insights that helped us design a more user-focused app. This also matched the project’s goal of raising environmental awareness, making the work both meaningful and impactful.

© Gemma Bao Tran, 2025

Email contact: gebao.nt@gmail.com