Senior Software Engineer (Backend) - Team Billing

We are a green-tech company shaping the energy industry towards a more sustainable future. At Lumenaza, you have the opportunity to actively contribute to the world of decentralized and renewable energy. Our mission is to drive the energy transition forward - with passion and innovation.

Lumenaza stands for clear values: sustainability, diversity, and collaboration. We take pride in our diverse team and are committed to supporting women in tech.

You will receive thorough onboarding into the processes of the energy market and gain access to an exciting, future-proof industry. We are well aware of the energy market's complexity, which is why we place great importance on sharing knowledge and ensuring that you can succeed - regardless of your previous industry experience., As part of our team, you will work on solutions for the billing and monetization of energy services and the related business processes.

• Contribute to the energy transition: You design and develop software solutions that enable our customers to reliably and efficiently implement complex tariff models, billing workflows, and accounting-related processes. Your work directly supports economically sustainable business models in renewable energy.

• Shape complex systems: From concept and implementation to quality assurance, you are involved in every step. You help design and evolve billing logic, data models, and product catalogs, ensuring long-term maintainability, scalability, and domain correctness.

• Solve technical challenges: Billing systems place high demands on accuracy, traceability, and performance. You develop robust and scalable solutions using Python and Django, working on data modeling, asynchronous processing, batch processing, distributed systems, and the integration of external billing and accounting systems, while tackling demanding design and performance challenges.

• Collaborate across teams: You work closely with colleagues from backend, frontend, DevOps, Product Management, and adjacent domains such as Finance and Operations. Together, you design cloud-based solutions, share knowledge, and actively shape architectural decisions. In an agile environment, you contribute to the continuous improvement of both product and processes.

• Stay curious and share knowledge: You keep up with current trends in software design, bring new ideas into the team, and support the continuous evolution of our billing platform.

• Bridge legacy and future: You help maintain existing systems while supporting their ongoing evolution and gradual modernization, contributing to the sustainable development of our billing and system landscape.

Do you want to help shape the energy industry of tomorrow? We value enthusiasm for sustainability over perfection - diversity and a willingness to learn are what count. Apply and help us shape the future.

• A degree in Computer Science, Business Informatics, or a comparable qualification
• At least 5 years of experience as a backend software engineer, ideally in domain-complex, data-driven systems
• Excellent knowledge of Python and Django
• Solid experience with the Django REST Framework
• Practical experience designing, developing, and integrating REST APIs
• Experience with microservice architectures and distributed systems
• Confident handling of Docker and Docker Compose
• Practical experience with pytest or similar testing frameworks
• Understanding of working with business-critical legacy systems and their evolution
• Passion for clean code, automation, and CI/CD
• Strong communication skills in English
• Experience working with PostgreSQL, Redis, and object storage (e.g., S3)
• Confident use of Git
• Experience working with Linux systems
• Knowledge of Celery and asynchronous programming

Nice-to-have

• Experience with Pydantic, FastAPI, or Django Ninja
• Experience using the Robot Framework for test automation
• Experience integrating external accounting or ERP systems (e.g., DATEV, SAP)
• Experience with Temporal or similar workflow orchestration tools
• Knowledge of TypeScript and React
• German language skills are a plus

Our Tech Stack

Most of our systems are built with Python and Django, with PostgreSQL as the primary database. We use the Robot Framework for system testing and deploy containerized code through a GitLab-based CI/CD pipeline to Kubernetes test and production environments. Frontend applications are implemented using React.

At Lumenaza, you'll find not only unique benefits but also a culture of support and continuous development:

• Comprehensive onboarding and training: Tailored programs and active knowledge sharing to support your professional growth.

• Flexibility for a better work-life balance: Flexible working hours and the option to work from home part of the week.

• Attractive additional benefits: Fair pay, a discounted electricity tariff, and a reduced-price Deutschlandticket.

• Modern work environment: An inspiring office in Berlin-Kreuzberg that fosters creativity and productivity.

• Innovation at the heart of the energy transition: Join a team working at the forefront of energy innovation and help shape a sustainable future.

Lumenaza develops powerful software to connect producers and consumers of green distributed energy, providing everyone access to the energy market. We unlock innovative businesses models based on green distributed energy resources, accelerating new energy. This enables businesses to increase core product sales and sell energy services to existing and new customers. Our platform significantly reduces time-to-market and cost-to-serve.We maximize value from renewable assets. Consumers benefit from knowing the clear origin of their energy and profit from innovative, individualized energy solutions