Selected work.
Systems we've designed, built and run for clubs, communities and our own homes. Several of them later became products.
RAYNET-UK DMR Server
RAYNET-UK is the UK's national voluntary communications service, provided for the community by licensed radio amateurs. We built and run its Digital Mobile Radio (DMR) server for members.
The server is divided into RAYNET groups and zones. Each group has 100 talkgroups, which its controllers can rename, enable, disable and put access control on, and controllers can invite members to join. Members send traffic through their own hotspots (the recommended method) or through some public repeaters. We also wrote a help site to support members using the service.
To request access, contact your local RAYNET group controller.
Octotrack
Octotrack pulls half-hourly consumption and export data, along with each meter's tariffs, from the Octopus Energy API. It charts usage over any period and predicts the month's bill. It also handles Intelligent Octopus Go extra sessions by repricing those half-hours at the cheap rate.
On our own system, which runs a house and three EVs, export brings the average price down to around 3.5p/kWh. If you'd like Octotrack for your own monitoring, get in touch.
Squash court booking screens
A squash club with five courts wanted booking information shown outside each court. Bookings are taken online through MyCourts, which offers no API.
We wrote a small web service that collects the day's bookings from MyCourts every few minutes, processes them once and caches them as a single JSON file. Only one system ever loads MyCourts, and the screens can poll the static file quickly with very little overhead.
Each screen is a 7" LCD driven by an ESP32 on the club WiFi. All screens run identical firmware. On first boot each one reads its WiFi credentials, data URL, court number and on/off times from an SD card, stores them, and the card can then be removed. This ESP32 display platform became the basis of our products.
A smart in-home display
Supplier in-home displays can't handle half-hourly smart tariffs and can't align with your billing date, so their costs are often wrong. Glancing at a phone isn't always practical either.
Using data already in Home Assistant, we built a kitchen display from an inexpensive ESP32 and a Nextion 2.8" touchscreen, integrated through ESPHome. It shows accurate live and period costs on the actual tariff.
Solar, battery & EV
In 2022 our energy supplier went bust and we were moved to British Gas. Running the house cost around £500 a month, and two petrol cars cost about £400 a month each in fuel.
The plan was to use only cheap overnight rates. A house using about 30 kWh a day needed roughly 28 kWh of battery storage and 10 kW of supply to cover high-draw appliances, and had to ride through power cuts without choosing which circuits to keep. Tesla Powerwalls, solar, a Zappi charger, three EVs, an Octopus smart tariff, Home Assistant and Octotrack together cut the combined energy and fuel bill dramatically.
We apply the same approach to client energy projects.