Offgrid Energy Labs
Product Manager - Battery Energy Storage Systems (BESS)
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About Offgrid Energy Labs
Offgrid is a deep-science, IP-led startup commercialising ZincGel, a sealed non-flow zinc-bromide technology for long-duration energy storage. With 70+ IP assets and cell manufacturing already underway at our facility in Hook, Hampshire, we are scaling globally through partnerships to establish gigafactories.
About the role
Our Hook pilot line is now producing bipolar stacks for the first time, and we are engineering the path from the stack, to modular kWh-class systems, to standalone systems that aggregate into MWh-scale field deployments.
We need a senior individual contributor to own the electrical and system architecture from the bipolar stack upward: through modules, packs, and systems, to how a multi-megawatt installation behaves on a customer's network. Ownership sits with you. The founders steer long-term vision and lead commercial and business development; the technical decision-making on system and product architecture is yours. You will direct a small execution layer across electrical, power electronics, and controls, rather than doing everything solo. This role shapes the product and builds the capability to deliver it.
What you will do
- Own system architecture from the bipolar stack upward: series/parallel topology, module and rack configuration, and the aggregation logic that scales a modular kWh building block to multi-MWh deployments.
- Set the system electrical design: DC bus architecture, string voltage and current limits, protection and isolation, earthing/bonding, and the PCS/inverter interface (DC- or AC-coupled).
- Set the BMS/EMS strategy, including the make-versus-buy decision, state estimation (SoC/SoH), balancing, protection, and communications (CAN, Modbus, SCADA), and direct its implementation.
- Lead the technical path from kWh systems to multi-MWh deployments, including design for storage collocated with solar and behind-the-meter bill optimisation for C&I customers.
- Define grid and site-integration requirements: connection topology, power quality, protection coordination, and commissioning for C&I and grid-scale sites.
- Own the safety, compliance, and certification strategy for grid-connected storage, and stay close to customers on the technical detail so the product is grounded in real deployment needs.
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What we are looking for
- Proven, hands-on delivery of battery energy storage systems at MWh scale in the field: architecture through commissioning, not paper design alone.
- Direct experience across both C&I behind-the-meter and grid-scale projects, including storage collocated with solar and bill optimisation for industrial and commercial customers.
- Strong power electronics and power systems competence: PCS/inverters, DC-DC conversion, DC bus design, protection coordination, and the storage-to-grid interface.
- Ability to work from stack-level electrical inputs upward, and BMS/EMS architecture experience (state estimation, balancing, protection, CAN/Modbus/SCADA) sufficient to set strategy and direct a build.
- Direct experience of site electrical integration and commissioning, with comfort engaging customers on technical detail.
- Comfortable as a senior individual contributor who directs a small execution team in a fast, early-stage environment working directly with founders.
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Chemistry-agnostic: depth of systems, power electronics, and deployment experience matters more than any specific chemistry. Cross-chemistry adaptability is a plus.
Nice to have
- UK grid connection and storage compliance: G99, BS 7671, IEC 62933, UL 9540A / 1973.
- Experience taking a storage product from pilot line to first commercial deployment.
- Design-for-manufacture exposure at module or pack level, and modelling/simulation capability (e.g. MATLAB/Simulink, PLECS).
How to Apply
Send your CV and a brief note on why this role excites you to careers@offgridenergylabs.com. If you know someone who fits, referrals are warmly welcomed. We review applications on a rolling basis and aim to move fast.
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