Power BI Developer Specialist

Ariston; Randburg; On-site; ZAR 900,000 - 1,300,000; Full time

Job summary

Ariston is seeking a seasoned Power BI Developer Specialist to own the reporting and semantic layer of an enterprise analytics platform in a regulated, high-volume environment. You will design and build semantic models, craft DAX measures, and ensure security, performance, and accuracy across multiple business units.

You will collaborate with functional analysts and data engineers, perform unit tests, and drive end-to-end reporting delivery from data to executive dashboards.

Qualifications

• Design and build semantic models and DAX measures for enterprise analytics.
• Own reporting layer end-to-end across a live, high-volume environment.
• Implement and maintain row-level and object-level security (RLS).
• Optimize performance: query folding, aggregations, incremental refresh, and DAX tuning.
• Collaborate with data engineering to surface data quality issues.

Responsibilities

• Design, build, and maintain semantic models over Azure data warehouse.
• Translate business requirements into reports and dashboards with stakeholders.
• Write complex DAX for layered calculations and ensure accuracy across grains.
• Implement row-level and object-level security for data access control.
• Tune performance for large datasets and manage dataset refresh pipelines.
• Conduct peer reviews of semantic models and DAX before promotion to production.
• Support testing cycles: UAT, defect triage, and remediation.

Skills

Power BI

DAX

Semantic models

ROLS

Performance tuning

Data modeling

Unit testing

Education

Microsoft PL-300 certification

Tools

Azure Data Warehouse

Power BI Service

Gateways

Deployment pipelines

Microsoft Fabric (advantage)

Job description

We are a lean, senior digital strategy and data analytics consultancy delivering high-stakes engagements across energy, mining, manufacturing, and telecoms. Our success is driven by collaborative thinking, precise execution, and building meaningful relationships that drive results. We believe in harnessing the power of innovation and teamwork to transform businesses and make a tangible difference in the digital landscape.

We are seeking an experienced Power BI Developer Specialist to own the reporting and semantic layer of an enterprise analytics and forecasting platform operating in a regulated, high-volume commercial environment.

This is a hands-on, senior specialist role on a live, business-critical system. You will design and build the semantic models and reports that translate complex, regulator-driven commercial logic into figures that executives and operational teams rely on to make decisions. Candidates who have only built departmental dashboards on clean, static data are unlikely to find this role a comfortable fit.

Key Responsibilities

• Design, build, and maintain enterprise-grade Power BI semantic models (data models, relationships, DAX measures) sitting over an Azure data warehouse.
• Translate documented business and functional requirements into report and dashboard designs, working directly with functional analysts and business stakeholders to confirm expected outputs before build.
• Write and optimise complex DAX for layered calculation logic, including rate- and classification-driven measures that must reconcile to source at more than one grain.
• Implement and maintain row-level security (RLS) and object-level security to enforce data access rules across business units and user groups.
• Own performance tuning of semantic models and reports — query folding, aggregation tables, incremental refresh, and DAX optimisation — for large, frequently refreshed datasets.
• Manage the Power BI Service estate: workspaces, deployment pipelines, gateways, dataset refresh schedules, and version control of published artefacts.
• Write and execute unit tests and reconciliation checks for all developed reports and measures before handover, and record the results as a delivery artefact.
• Participate in mandatory peer review of semantic models and DAX, both as author and reviewer, prior to promotion to production workspaces.
• Support System Integration Testing and User Acceptance Testing, including defect triage, root cause analysis, and remediation within agreed turnaround times.
• Maintain technical documentation: data model diagrams, measure dictionaries, source-to-report mappings, and RLS matrices.
• Work closely with the data engineering team to flag upstream data quality or structural issues surfaced during report build.
• Provide light-touch training and walkthroughs to business users adopting new or changed reports.

This is the differentiating requirement for this role.

Essential Domain Experience

• Building semantic models and DAX measures over pricing, tariff, or rate structures where the applicable rate varies by customer category, time period, seasonal window, or usage band.
• Reporting across multi-level customer or product classification hierarchies, where drill paths and totals must remain correct as classifications change over time.
• Handling effective-dated reference data and slowly changing dimensions in DAX, including correct point-in-time and as-at reporting.
• Rebuilding or re-validating reports and measures following an externally driven restructure — regulatory, legislative, or commercial — that changed the underlying calculation logic.
• Reconciling report-level totals against source and actuals at more than one grain, and explaining variances to non-technical stakeholders.
• Large-model performance work: composite models, aggregations, or incremental refresh on datasets with meaningful history and volume.

Certifications

• Microsoft PL-300 (Power BI Data Analyst Associate) is required.
• A funded pathway is available for a strong candidate who is not yet certified.
• Familiarity with Microsoft Fabric's reporting capabilities is an advantage.

What We're Looking For

• You treat a DAX measure the same way an engineer treats code — tested, reviewed, and documented, not just “working.”
• You ask business stakeholders what a number should be before you build it, not after they complain it's wrong.
• You are comfortable being the person who owns the reporting layer end to end.
• You write documentation that someone else could actually pick up.