At a Glance
- Tasks: Lead software design and strategy while collaborating with a dynamic engineering team.
- Company: Join Joulen, a pioneering energy tech company transforming the market.
- Benefits: Enjoy 22 days leave, private medical insurance, and a supportive work culture.
- Other info: Embrace autonomy and growth in a fast-paced, innovative workplace.
- Why this job: Make a real impact in the renewable energy sector with cutting-edge technology.
- Qualifications: Proven experience in software engineering and leadership in tech environments.
The predicted salary is between 63000 - 77000 £ per year.
The energy system is changing fast.
As renewable generation and electrification spread, flexibility becomes more valuable, and assets such as home batteries, commercial and industrial batteries, electric vehicles and grid-scale storage can all help balance supply and demand.
Capturing that value takes direct market access, sophisticated forecasting and real-time optimisation.
Joulen provides all three.
We trade directly in energy markets and use our platform to forecast tradable volumes and find the strongest opportunity in any given period, so flexible assets earn more than they otherwise would.
We do this with installers, energy retailers and OEMs, who gain a stronger customer proposition and a new revenue stream, while asset owners see better returns and the grid gets more flexibility.
The role
As a Principal Software Engineer you are the senior technical authority for one or more of Joulen's product domains, sitting between Senior Engineer and Head of Engineering on our Software Engineer career track.
You set the design principles, delivery strategy and operational standards for your domain, and you work with the other Principals & Head of Engineering to shape how engineering works across Joulen.
You stay hands-on: you pair, write tests first and ship small increments to trunk like everyone else.
Your leverage comes from turning GB energy-market change into sound platform and architecture decisions, and from growing other senior engineers.
Key Responsibilities
- You will be the technical authority for your product domain, and the person who understands the relationship between your engineering domain and product propositions it serves.
That means understanding our products such as Flex, Trade and Grid.
- You will set the standards that keep our systems simple, tested and safe to change at scale.
You define the design principles, test strategy and coding standards for your domain, own its technical-debt strategy, and arbitrate the significant trade-offs between systems.
- You also shape our continuous delivery and release strategy, so that engineers can ship small changes to production frequently and confidently.
- You will own the reliability of what we run and how we use AI to build it.
You set operational standards and the incident framework for your domain, and you help lead Joulen's agent engineering practice, including how AI is governed in production software.
- Beyond your own systems, you will shape how engineering works across Joulen.
With the other Principals you will design team interaction models for fast flow, build the ownership and review norms that keep the codebase collectively owned, and set the standard for how engineering communicates, up to board and external audiences.
- You will grow other senior engineers, influence hiring, and help keep a culture where problems surface quickly and are resolved without politics
- Demonstrable, hands-on Extreme Programming practice: TDD, DDD, pair and mob programming, continuous refactoring and simple, emergent design.
- A track record of defining continuous delivery strategy with trunk-based development, feature flags and progressive delivery.
- Experience setting design principles, test strategy and operational standards across several systems or teams, not just your own.
- Ownership of production reliability: observability, incident frameworks and reducing MTTR.
- Fluent AI-native engineering, with a view on governing AI and agent-driven systems in production.
- Working knowledge of Team Topologies and how team boundaries shape architecture and flow.
- Clear, persuasive writing (ADRs, strategy papers, postmortems) for engineers, commercial colleagues and board-level readers.
- A history of developing senior engineers and shaping hiring.
- Experience in GB electricity markets, flexibility, trading, dispatch or settlement. If you don't have it yet, you'll need the appetite to become an authority quickly.
- Experience designing platforms and systems for agentic or AI-assisted delivery.
- A profile in external software engineering or energy-industry forums.
What we offer
- 22 days annual leave plus 11 public holidays
- Option to buy additional annual leave
- Pension
- Life Assurance
- Private Medical Insurance
- How We Work
Joulen runs on six operating principles: Customer Centricity, Talent Density, Move with Urgency, Radical Candour, Disagree & Commit, and Owner-Operators.
In practice that means you will be given the outcome and the autonomy to get there, you will get direct feedback and be expected to give it, and you will be trusted to make decisions in your area without waiting for permission.
New joiners go through Joulen Bootcamp, our structured onboarding programme, so you will understand the energy markets we operate in and how our product works, not just the ledger.
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Principal Software Engineer Engineering Belfast / Hybrid employer: Joulen
Joulen is an exceptional employer located in Belfast, offering a dynamic work environment where finance plays a crucial role in the rapidly growing energy flexibility sector. Employees enjoy competitive salaries, generous leave policies, and comprehensive benefits including study support for professional qualifications, all while being part of a collaborative team that values autonomy and personal growth. With a strong focus on employee development and a culture that encourages innovation and direct feedback, Joulen provides a unique opportunity to shape the future of energy trading and settlement processes.
StudySmarter Expert Advice🤫
We think this is how you could land Principal Software Engineer Engineering Belfast / Hybrid
✨Join Local Tech Meetups
Get out there and mingle with fellow developers by joining local tech meetups. It’s a fantastic way to meet people who might be working at Joulen or know someone who does. Plus, you can pick up some trendy tech skills and trends while you're at it!
✨Contribute to Open Source Projects
Show off your coding chops by jumping into open-source projects. Not only does this give you practical experience, but it also gets you noticed in the dev community. You'll create a killer portfolio that speaks volumes about your skills to Joulen.
✨Tap into Online Developer Communities
Don’t underestimate the power of online developer communities like GitHub, Stack Overflow, and even Reddit. Participate in discussions, share your projects, and build your visibility. We can often find opportunities through these channels that can lead to a full-time gig at companies like Joulen.
✨Explore Job Boards Specifically for Tech Roles
Keep your eyes peeled on job boards that focus on tech roles. Sites like TechCareers or Stack Overflow Jobs can often have listings for companies like Joulen that might not show up on broader job sites. Make it a habit to check these regularly, and don’t hesitate to apply directly through our website!
We think you need these skills to ace Principal Software Engineer Engineering Belfast / Hybrid
Some tips for your application 🫡
Show off your coding skills:When applying for a software engineering role, it's super important to showcase your coding skills. Make sure your CV includes your tech stack, any relevant programming languages you’re comfortable with, and examples of projects you've worked on. If you have a GitHub profile, link it up! We love to see code in action.
Tailor your portfolio:For a full-time role, we’d expect to see some solid examples of your work in your portfolio. Make sure to include at least two or three projects that highlight your problem-solving skills and your ability to work with different technologies. Focus on the projects that are most relevant to the position at Joulen.
Craft a killer cover letter:Your cover letter is your chance to stand out—make it personal! Explain why you want to work at Joulen and how your skills align with the role. Show us your passion for software development. We dig enthusiastic candidates who understand the value of collaboration and continuous learning!
Be clear and concise:When it comes to writing your CV and cover letter, clarity is key. Avoid jargon that could confuse us and stick to simple, direct language. Highlight your achievements with quantifiable results where possible, and keep everything easy to read. A well-organised application goes a long way!
How to prepare for a job interview at Joulen
✨Brush Up on Your Coding Skills
For a full-time software engineering role, it's crucial that we stay sharp with our coding abilities. Expect technical questions that might involve solving problems on the spot or discussing algorithms. Practise on platforms like LeetCode or HackerRank to get comfortable with the types of questions that often come up.
✨Know Your Tools and Frameworks
Make sure we’re well-acquainted with the tools and technologies listed in the job description. Familiarise ourselves with any specific frameworks or programming languages mentioned. If Joulen uses React or Node.js, for instance, be ready to discuss how we’ve used them in previous projects or coursework.
✨Showcase Your Projects
Bring along a portfolio that highlights our best work. This could be code samples, GitHub repositories, or any side projects we’ve built. Make sure we can talk through our thought process for each project, especially the challenges we faced and how we solved them—this shows our problem-solving skills in action.
✨Prepare for Behavioural Questions
While technical skills are key, full-time positions also require cultural fit. Be ready to discuss our previous experiences and how we handle teamwork, conflict, and deadlines. Brush up on the STAR method—Situation, Task, Action, Result—to clearly articulate our past experiences when discussing how we've contributed to a team.
