case study sonnen

How to deliver an MVP when your in-house development team is busy?

case study sonnen


Solar energy

model / length

Scrum/5 months


4 Developers, Designer & Scrum Master

Executive Summary

When sonnen turned to XSolve they had only a few months to develop an MVP of their customer portal. Their in-house development team was tied up with other products, and the deadline did not allow sufficient time to recruit new developers and designers. 

sonnen wanted to create a customer window to the intangible world of self-sustainability and solar energy, as provided by sonnen’s core product, the sonnenBatterie. Apart from acting as an engagement tool, the customer portal would also be an important element of the company's marketing strategy, with customers acting as brand ambassadors and showcasing the web app to their friends and neighbors. 

XSolve delivered a fully self-organizing Scrum team in just four days from the first contact by sonnen. A full, interdisciplinary development team, consisting of Designer, Frontend Developers, DevOps and Scrum Master, was carefully selected to meet the client's needs. The XSolve team created an MVP of the customer portal working hand-in-hand with sonnen’s Product Owner and in-house designer. The team sculpted a completely new user experience and improved the user interface, all in line with sonnen’s brand identity. The resulting responsive web app is fully scalable and performs exceptionally well in terms of loading time, achieving the product KPIs.

The customer portal is now live and new features have been added with every sprint. Following the success of the collaboration, sonnen has partnered with XSolve to deliver new products.

From the start the collaboration was based on mutual trust. From the start Sonnen was very opened to all suggestions that XSolve development team has proposed.

What we did


"The XSolve team really feels like they are sonnen employees. They work on an equal footing and collaboratively with our team members. This allows us to create a better experience for our customers."

Norbert Baumann,

VP Research & Development / Digital


Established in 2010, sonnen is a quickly growing company operating in the renewable energy and technology sector. The company is the global leader in residential energy storage and operates throughout Europe, USA, Australia and more. Its core product is the sonnenBatterie, a home energy storage system for private homes and small to mid-size businesses. sonnen ships a ready-to-use system containing battery modules, an inverter, a power measurement system and an intelligent, internet-connected energy controller. After it has been installed at the customer’s site it can store energy collected from PVs and distribute that energy around the house as well as pass it on to other people registered in the sonnenCommunity. Furthermore, the product has the potential for more extensive use; for example, building a virtual power plant consisting of thousands of sonnenBatteries for storing or providing excess energy, achieving sustainability and stability on the electrical grid.

The mutual visits in our HQ in Gliwice and at Client's office in Sonnen allowed the team to reach high-performance quickly.

sonnen customer portal MVP case study outsourcing web development and design xsolve
sonnen customer portal mvp xsolve web app


- sonnen clients are highly engaged consumers who are eager to see the effect of their sonnenBatterie. Most importantly, they want to observe how the system works and what impact it has on the environment, how self-sustainable they are, how the energy is shared within the sonnenCommunity, and how they help to stabilise the power grid.

- Electricity is an intangible product and thus sonnen decided that their customer portal would be a tool to keep customers engaged after they have bought the system. The customer portal is a way to visualize all relevant information for all their products, like the sonnenBatterie, Smart Home accessories and the sonnenFlat energy contract. 

- The previous version of the customer portal had only the must-have features and offered some data, but it was very technical, complex and not visually appealing.

- sonnen wanted to take the portal to the next level, simplify the data presented and make it user-friendly as well as coherent with the rest of the brand.

- The web app needed to be easy to be understood by everyone, so sonnen customers would proudly show it off to their neighbors and become ambassadors for the brand.

- In September, sonnen decided to launch the new customer portal by the end of the year and test it on real users to make further improvements in the future.

- Their in-house team of developers was tied up with other products and they quickly needed a fully self-organizing team.

- sonnen realized that the process of recruitment and training can take up to 3-6 months and with a December deadline on the horizon they were unable to reach it without an external partner.

- sonnen had most of the designs ready but needed a graphic designer onboard to work alongside the development team to further enhance the designs, add new views for the app, and create all mobile views for the responsive version, as well as oversee the implementation.

- The Client realized that the the old customer portal was not scaling very well, with integration of new features affecting the rest of the web app.

- Additionally, the loading times of the old portal were high, with customers having to wait several seconds until the page and data loaded, not only in Europe but also in the US and Australia.

- The KPIs for the new portal included that it be stable, live and running, with easy integration of new features, plus reduced page loading times and minimal downtime.

- From the customer perspective, sonnen wanted to achieve a top-notch user experience as well as an amazing digital experience. For the MVP of the new customer portal, sonnen planned to measure the satisfaction of users through surveys, aiming for an average score of 4 out of 5 or higher.



“What we really gained from the collaboration was a partner that is not only doing what we asked them to do but is also thinking and giving feedback. We really enjoy the input from each individual team member, not only about the technology but also about the content and design.”

Norbert Baumann,

VP Research & Development / Digital


- sonnen selected a number of partners who stood in terms of technological fit. They began their research by visiting websites, looking not only for more information about processes but also searching for a cultural fit - a startup atmosphere within an enterprise business. They contacted several potential partners and had initial talks. XSolve stood out as a company who really wanted to understand their problem and fulfill sonnen’s needs.

- XSolve kicked off the project four working days after the initial contact with a fully self-organized team.

- From the beginning the product was developed in a Scrum framework with one week sprints. 

- The Product Owner was on the sonnen side and the XSolve team, based in Gliwice and Warsaw, had a remote kick off meeting with a presentation about the sonnen company as well as the vision and goals for the product. They also established a structure for the coming weeks as well as dependencies between people and their responsibilities.

- XSolve carefully selected the team members to suit the client’s needs, choosing people who had worked together in the past. Product development started with three frontend developers, a DevOps Specialist and a Scrum Master. Two weeks into the development process, it was agreed that the help of the XSolve designer was crucial and thus she joined the team. sonnen’s in-house backend developer assisted in product development and onboarded the team with respect to the existing infrastructure, highlighting certain considerations for coding. The team was interdisciplinary, with all the skills necessary to complete the mission.

- sonnen provided XSolve with some initial designs. The team’s goal was to prepare a responsive web design for the web app as well as rethink the UX for the customer portal based on the user stories discussed during workshops.

- In November, sonnen recruited an in-house designer who also joined the team. The new designer was based at sonnen’s HQ in Wildpoldsried and was on-boarded by the XSolve team, working with them together hand-in-hand from the day one.

- XSolve built the Customer Portal with React. It is hosted on Amazon Web Serivces and it uses various libraries like Redux and Highcharts.

- The XSolve team visited sonnen HQ two weeks after the project kicked off for further onboarding on-site. sonnen visited XSolve’s HQ every month and the team from Gliwice travelled to Germany twice. These face-to-face interactions helped to form bonds between project members and a better understanding of the business needs for the product.

- Both XSolve and sonnen worked very closely together and from the beginning the collaboration has been transparent and agile. XSolve’s Scrum Master helps the team to follow the process and looks after

- The team held daily meetings online, discussing obstacles and asking questions about the product, solving them on the spot or within 24 hours. Throughout the day, everyone was in constant contact via Slack. The designers in both companies held additional calls regarding UX and UI, constantly updating each other on progress and changes as well as making sure that everything was in line with the sonnen brand. The review, retrospectives and planning meetings were held via Google Meet, with the whole team taking part across Gliwice, Warsaw and Wildpoldsried. 

sonnen customer portal MVP case study

“The XSolve team really feels like they are sonnen employees. They work on an equal footing and collaboratively with our team members. This allows us to create a better experience for our customers and that is hugely important. XSolve treats the customer portal as their product and this resulted in the high quality of their work.”

Norbert Baumann,

VP Research & Development / Digital


Delivering a Customer Portal that fulfils the user needs.

- In early December, a first version of the product was released to a small group of customers, tested and iterated, and the full release went live in February. 

- The product is now live and the team measures the page loading time and uptime. The results are very satisfactory for the client. 

- sonnen has carried out customer satisfaction surveys and so far the response has been incredibly positive with an average score of 4 out of 5.

- sonnen continues to work with XSolve on further development of the customer portal. Currently, the team is testing new functionalities, gathering user feedback, analyzing it and developing the product accordingly using lean startup approach.

- Following the success of the collaboration, sonnen has also decided to partner with XSolve on their new flagship project which was launched in February 2018.

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