About

I invent small useful things and give them away. Mostly home energy, home automation, and civic data — the kind of tools nobody else is going to build because the niche is too narrow, but a handful of people genuinely need. Some of them are working hardware. Most of them are open source. All of them came out of an itch I wanted scratched in my own life first.

Things I've made

Roughly newest to oldest. None of these are products in the commercial sense — they exist, they work, the code is public, fork or use them as you like.

• An Octopus Agile charge planner. A cron-driven Python planner that books grid-charging during cheap Agile half-hour slots while keeping the battery above its SOC floor. Multi-stage decision pipeline (predict slots → compute gaps → trim by per-slot price ceiling → emergency safety net), drift detection on round-trip efficiency and wire temperature, push alerts when something drifts beyond its rolling baseline. Lives in this site's repo and runs my own home setup. The decision history is on the live solar dashboard.
• A clean local-storage pattern for HA daily metrics. Most HA energy dashboards lie about daily totals because the underlying sensors don't reset cleanly at midnight. Built a tiny SQLite table populated nightly from the cumulative-counter at 23:00 BST — immune to the various Victron, LTS, and recorder-timing bugs that corrupt the official numbers. Now feeds the all-time-record crown banner and Top-5 list on the dashboard. Architecture write-up here.
• Wire-temperature instrumentation for home batteries. Two £3 DS18B20 sensors clamped to the high-current cable caught a 76°C fault on my old busbar that no BMS dashboard would have shown. The pattern — instrument the wire, not just the cells — flagged a degrading thermal margin before any visible failure, and the busbar was swapped on data alone. Story and numbers here.
• bin-cal — Subscribable UK bin collection iCal calendars. Drop the URL into your calendar app once and bin day shows up automatically. Built because remembering bin day shouldn't require checking a council website.
• HA Battery Smart-Charge blueprint — A Home Assistant blueprint that does smart battery charging against Octopus Agile rates with SOC and plunge override. For people who want a planner without writing the Python.
• Octopus Greener Days forecast card — A Lovelace card that shows Octopus Energy's Greener Days score in your HA dashboard. Visual nudge for when to run the dishwasher.
• Council bin-schedule sources. Upstream contributions to the popular HACS waste-collection-schedule integration: added Kingston, added Mole Valley, and rewrote Kirklees for the new my.kirklees.gov.uk API. Other people's calendars now light up correctly because of these.
• Real-time GPS tracking for travel. A live-location sharing system built during the Central-Core years so people could follow along during long motorcycle trips across Europe and Southeast Asia.
• Home Assistant core: URL input for Prowl notifications (#46427). Small but useful — let people point Prowl at non-default endpoints. Plus a couple of documentation PRs.
• Timezone fix for octopus-energy-rates-card — popular community card for HA dashboards. Was breaking outside UTC; now isn't.
• OpenEnergyMonitor notifications. The notifications layer for the foundational UK open-source home-energy project, back when it was just getting going (#4, #5). Didn't endure in mainline. The project did.
• Arduino early-days community work. Active in the formative years of the platform — hardware experiments and a few smaller contributions when the ecosystem was still being figured out. Less linkable than the GitHub-era work but the start of the same habit.

Full list of public repos: github.com/elyobelyob (and github.com/elyob in earlier years).

The thread

Across all of it, the same instinct: instrument something, surface the data, make it public. Started with embedded hardware in the Arduino days, moved through home-energy monitoring (OpenEnergyMonitor, Home Assistant), civic data (council bin schedules), and now home solar and battery on Octopus Agile. Each step has been a system I didn't fully understand until I started measuring it.

The 700 W solar array on the patio in Surbiton is small. The instrumentation around it isn't. The numbers on the ROI page and the live solar dashboard are computed from real meter and sensor data, with the methodology in code, not from vendor screenshots.

Day job (briefly)

Senior back-end developer for 25+ years across PHP, Symfony, Laravel, Node.js, AWS. Founded Central-Core.com (2015–2022), an IoT and home-automation venture working with IBM and British Gas on utility-usage analysis and reduction — that's where the energy-instrumentation thread became professional rather than just a hobby. Earlier career across FTSE-listed publishing (Informa), banking compliance (Halifax Cetelem in Paris and London, Daiwa Europe, Zurich, Eagle Star), telephony (Regus), and luxury e-commerce (Mr Porter, Moncler at Wednesday London). It's the credential plank, not the story.

Other things

Solo motorcycle tour of 18 countries on a 2014 KTM 1190 Adventure. Land's End to John o' Groats charity cycle. PADI Advanced Open Water diver. RYA National Powerboat Certificate. No car for thirty years; everything by scooter, bike, train, or ferry. Live in Surbiton.

Contact

Best way to reach me is via GitHub. PRs and issues welcome on any of the repos above. Comments on posts here are read. If you build something on top of any of this, drop a link — that's the best response any of these get.