Product Engineer (Mid-Level / Senior)
Sunsave
Sunsave builds a solar-plus-battery alternative to energy suppliers, offering kit, install, finance and battery trading to drive customers' bills towards zero. The Product Engineer will join a small squad (acquisition, installation, in-life or energy) and own problems end-to-end from user research to running services in production.
What you’ll do
- Own problems end to end from working with users to running in production
- Join a small squad focused on acquisition, installation, in-life or energy
- Delegate implementation to agents while retaining design and ownership
- Ensure correctness, auditability and security of systems
What they’re looking for
- 2+ years running production software for mid-level
- 6+ years running production software for senior
- Right to work in the UK required
- Experience with TypeScript, NestJS, React/Next.js, PostgreSQL and AWS is a plus
Skills
- TypeScript: TypeScript
- NestJS: NestJS
- React/Next.js: React, Next.js
- PostgreSQL: PostgreSQL
- AWS: AWS
- AI / agents: AI, agents, AI tools
The post
Sunsave | Product Engineer (Mid-Level / Senior) | London, United Kingdom (Holborn) | ONSITE (hybrid, 3 days/week in office) | Full-time
Sunsave is building what replaces your energy supplier. Customers switch to solar and a battery with nothing to pay upfront: kit, install, finance and long-term protection in one package, and the battery trades energy on the grid every day to push their bills towards zero. Founded in 2022, £113m Series A (equity and debt) in 2025, more than 3x growth last year, nearly 90 people.
I lead engineering and data science. Software runs every step of the customer journey: the quote, the finance application, the contract, the install and the battery trading. You'd join a small squad on one area: acquisition (website, quote, finance, contract), installation, in-life (customer app, monitoring, maintenance) or energy (battery optimisation and grid trading).
Product engineers here own problems end to end, from working with the people who use what they build to running it in production. Agents do a lot of the implementation. We expect you to use them every day, delegate the implementation but never the thinking, and own every line you merge. We offer finance and hold customer data, so correctness, auditability and security matter a lot.
Experience: 2+ years running production software for mid-level, 6+ for senior. TypeScript, NestJS, React/Next.js, PostgreSQL and AWS are a plus but not required. Right to work in the UK required.
The interview is built for how we work. No leetcode. A ~45 min async review of a pull request written with AI, then a ~90 min live session where you shape and build a small problem close to our work with your own AI tools.
JD: https://sunsave.notion.site/Sunsave-Product-Engineer-410e7b62a21d8141b04deaa4656a1b17 Apply: https://ats.welcometothejungle.com/board/sunsave-RTBuAt/job/e4f90cf7-9f97-4874-b1b1-8cf9643b239f