Job Description

Are you an experienced IT professional with a passion for infrastructure excellence, cutting-edge technologies, and driving business-critical IT solutions? We're looking for an

IT Senior Infrastructure Specialist

to join our team and play a central role in delivering robust, secure, and innovative IT services that support the growth and success of our organization.


The Calisen Group are a forward-thinking renewable energy organisation committed to leveraging technology to drive efficiency, security, and innovation. Our IT department plays a vital role in enabling our business goals by ensuring our infrastructure is dependable, secure, and adaptable to the evolving digital landscape. This is a unique opportunity to join a team that values collaboration, expertise, and the pursuit of excellence.


As the

IT Senior Infrastructure Specialist

for Calisen, you will lead the charge in ensuring our IT systems are secure, resilient, and optimised for the future. Reporting to the Service Delivery Manager, you will be the go-to technical expert, managing and evolving our infrastructure while supporting key business projects. You will...

Own the IT infrastructure

: Manage, document, and maintain a holistic understanding of the technical architecture, identifying risks and opportunities for improvement.

Drive innovation

: Introduce and implement emerging technologies, ensuring the business remains at the forefront of IT advancements.

Ensure robust security

: Maintain compliance with IT security principles and standards, including ISO27001, and respond to external security audits.

Resolve critical issues

: Act as the focal point for major incidents (P1) and lead the resolution of complex technical problems to minimize business impact.

Deliver projects

: Provide architectural direction, technical leadership, and hands-on delivery for IT infrastructure projects, ensuring alignment with business objectives.

Collaborate across teams

: Partner with internal and external stakeholders, including service desk teams, IT management, suppliers, and third-party providers, to enhance service delivery and reliability.

Key Responsibilities:

Technical Expertise and Leadership-

Maintain deep knowledge of our IT operating environment, including: + Microsoft Windows Operating System (Client & Server).
+ Microsoft Azure, Active Directory (AD/AAD), and Entra.
+ Microsoft Office 365, Dynamics, and SQL Server.
+ Microsoft Endpoint Manager (Intune).
+ Networking technologies (IP, DNS, LAN, WAN).
+ Cloud computing platforms and mobile device operating systems (iOS, Android).
Resolve complex technical issues and provide expert guidance to IT teams and stakeholders. Lead the adoption of innovative technologies to enhance performance, scalability, and security.

Security and Compliance-

Maintain a strong security posture, identifying areas for improvement in line with evolving threats. Work with IT security teams to ensure full compliance with ISO27001 and GDPR. Respond to external IT infrastructure and security audits.

Project Delivery and Service Improvement-

Lead infrastructure upgrade projects, ensuring minimal disruption to business operations. Provide architectural input and technical expertise to support key business initiatives. Identify and implement service improvement initiatives to drive reliability and availability. Execute refresh projects and adopt new technologies to sustain IT infrastructure for future growth.

What We're Looking For:

Recognised IT qualification or equivalent experience. Specific Microsoft accreditation (e.g., MSCE). Strong familiarity with ITIL framework and best practices. Proven experience in a senior IT infrastructure or support role, with a track record of resolving complex issues. Experience working in a customer-facing IT support capacity. Advanced expertise in Microsoft technologies (Windows OS, Azure, Office 365, Intune, SQL Server, and more). Knowledge of networking protocols and infrastructure (IP, DNS, LAN, WAN). Strong understanding of IT security principles, standards, and technologies. Experience with mobile device management and operating systems (iOS, Android). Advanced problem-solving skills, with the ability to resolve novel and complex technical issues. Exceptional customer service and stakeholder engagement skills. Strong project management and organisational abilities, with experience leading technical change. Excellent communication skills, capable of translating technical concepts for diverse audiences.
Please note: All successful applicants must pass a basic criminal record check, provide suitable references covering the last 5 years', and prove their eligibility to work in the UK.

What We Offer:

NEW! Competitive Salary

: 62,000 salary per annum, with our annual salary review ensuring your efforts are always rewarded.

NEW! Birthday Off

: Celebrate your day, on us!

NEW! Life Assurance

: Protection for you and your loved ones (4x your salary).

NEW! Enhanced Maternity & Paternity Leave

: Supporting you through life's biggest moments.

NEW! My Rewards Platform

: Discounts from hundreds of top retailers, just for being part of the team.

30 Days Holiday

: Increasing to 33 days with service (including bank holidays).

Company Sick Pay:

Supporting you during unexpected health challenges.

Pension Plan

: Secure your future with our robust pension scheme.

Electric Vehicle Salary Sacrifice Scheme

: Drive into a greener future.

Health-Shield Benefits Program

: Enjoy discounts, claim back on health expenses, and more.

24/7 Employee Assistance Plan

: Because your mental health matters. *

Professional Growth Opportunities

: Join a rapidly expanding market leader where your career can thrive.