Energy Lens
What happens during the day?
A low overnight price can come with a higher daytime rate. Compare both against your home’s pattern, with standing charges included.
The cheap night rate is only part of the bill.
Compare electricity tariffs against your whole household: daytime use, standing charges and the car on the drive.
Energy Lens uses your half-hourly readings, or a clearly labelled simulation, to show what a different tariff or charging time could change.
Free to use. Open source. No Energy Lens account.
Same energy. Different time.
Made-up exampleMove the car’s charging to see how the pattern changes.
HomeCarShading: cheaper hours
Charging on arrival£1.97example EV energy per day
The same 6.6 kWh of car charging, priced at the time it is used.
Illustration only: fictional rates of 30p/kWh by day and 10p from midnight–06:00. This is synthetic data, not anyone’s meter readings or a tariff quote. The full app also counts household use and standing charges.
Your readings stay with you.
Files are read on your device and saved in your browser. There is no account to create, no readings upload and no analytics. Download a private backup whenever you need one.
Look at the whole bill.
What if the car charged later?
Try different plug-in hours and charger power. With measured EV readings, only the car’s energy moves; the rest of the household stays in place.
How much can I trust the result?
Check the imported dates and missing half-hours. Gaps remain visible, and incomplete data is never quietly filled with invented consumption.
From meter readings
to a useful comparison.
Start with the annual kWh on your bill if you want to explore. Bring half-hourly data when you’re ready to compare the timing you actually measured.
Read the EDF and Glow data guideGet your electricity use
Download half-hourly consumption from your supplier, or use the local Bright / Glow connector after verifying your smart meter.
Import and check it
Match your timestamp and kWh columns. Review the dates, totals and missing intervals. CSVs and saved Energy Lens backups are supported.
Compare your quotes
Enter the rates for your region and tariff. Compare the recorded pattern, or explore charging scenarios using clearly stated assumptions.
Built from an ordinary question about an EDF bill.
Energy Lens grew out of trying to understand an EDF bill. It brings consumption, charging times and tariff rates into one place so you can examine the assumptions.
The dashboard, calculation engine and local connector are all open source under the MIT licence. The connector can download available Glow history, work from a local CLI, and expose energy analysis through MCP tools.
Explore the sourceA few practical questions
Am I looking at someone else’s private data?
No. This introduction uses a fixed synthetic example. A fresh dashboard starts with editable example inputs. Your own imports are stored in your browser and are not published for other visitors.
Does it only work with EDF?
No. Other suppliers’ half-hourly electricity CSVs can work too, using column mapping. The time calculations use UK local time, and the bundled price examples are for London. Enter quotes for your own region before making a comparison.
Do I need a smart meter or an electric car?
A smart meter provides the half-hourly history for measured comparisons. You can explore an annual simulation using bill totals without it. If you do not have an EV, set home charging to zero in the app.
Will my data follow me to another device?
Download a private JSON backup from Data & method, then import it on the other device. Saved data is specific to the browser and website address; it does not sync automatically.
Bring your own numbers.
See what changes when the whole household is included.