One File · Powerful health tracker
Every kWh produced.
Every pound saved.
A solar & home energy log in one HTML file. Production, consumption, payback period — for the householder who wants to know whether the panels actually paid back.
One payment · Yours forever · 14-day refund
- Works fully offline
- Installs as an app (PWA)
- No account, ever
- Yours, forever
Loads once, never needs the internet again. On a plane, in a basement, in a foreign hotel.
Every entry, every chart — stored locally. We never see it. We can't.
No subscription. No upgrades. No re-up next year. One file, yours.
Why log
Why solar households end up with their own books.
Inverter apps go away; payback is a 10-year question.
Payback-banner does the actual financial math.
Saved (self-consumed × import rate + exported × export rate) vs install cost. Same number a financial adviser would compute.
Self-sufficiency % reveals real grid independence.
How much of your consumption was from solar vs. grid. The number you can quote at the dinner party.
Production by weather reveals install quality.
Avg kWh on bluebird vs. mixed-cloud days. Real data on what the system actually delivers.
Lifetime kWh tier card is satisfying.
Most domestic systems generate 5,000+ kWh/year. After 5 years that's 25,000 kWh. Visible.
5.4kWp + battery
year of daily logs
no recurring fee, ever
no inverter integration
Inside the file
Eight things you'll use every day. Plus a dozen more.
One file. One dashboard. Every feature you'd expect from a "real" app — without the cloud, the cookies, or the £8/month.
Quick add
Log a reading from the home screen — three taps and back to your day.
Live insight banner
The single number that matters today, computed in real time from your entries.
Streak calendar
Daily streak across the last weeks. Showing up becomes the default.
Tier progression
Lifetime totals roll into satisfying tier badges as you log.
Total kWh imported vs exported (30d)
Ranked list updated every time you log — the leaders surface naturally.
Searchable, sortable list
Every entry findable in seconds — search across notes, sort by anything.
Free-form notes
A textarea per entry for the things that don't fit a field.
PNG share cards
One-tap share card of your stats, ready for Instagram or a group chat.
Offline, always
Loads once, runs forever without a network connection.
Installs as a PWA
Add to home screen — opens like any native app.
CSV in / CSV out
Bring your old data in. Take everything with you. No lock-in.
No account, ever
No email, no signup, no analytics, no third-party tracking.
Yours forever
If we vanish tomorrow, your tracker keeps working — local file, no server.
Light + dark
Auto-follows the system. Or pick one and stick with it.
Today
Today, at a glance.
The home screen pulls together what just happened and what's coming up — clean enough to actually look at every morning.
- Live insight banner — your unique angle, computed from your entries
- Four-tile stat grid surfacing the numbers that matter today
- Streak calendar showing the last weeks at a glance
- Quick-add button — log without leaving the home screen
- Recent entries on the dashboard so the last log is one tap away
System
Every system, in one place.
Name, system capacity (kwp), panel count, battery installed per row. Sortable, searchable, groupable.
- Search across name, notes / installer
- Sorted by name (A→Z)
- 12 fields per entry — the right amount of detail
Readings
Every reading, in one place.
Date, generated today (kwh), consumed today (kwh), exported today (kwh) per row. Sortable, searchable, groupable.
- Search across notes
- Sorted by date (newest first)
- 8 fields per entry — the right amount of detail
How it's different
What you give up vs. inverter apps. Auto-pulling readings.
Compared with manufacturer apps.
- Pricing modelPay once · $8.99£8 – £15 / month, forever
- Account requiredNoYes
- Auto-pull from inverterNoYes
- Payback period calcYesLimited
- Self-sufficiency % gaugeYesYes
- Data stays on your deviceYesNo
- Survives manufacturer shutting down appYesNo
The promise
Your panels' data is yours.
Even if the manufacturer's cloud isn't.
Offline, always
Open it once, never need the internet again. The file holds the whole app.
Local-first storage
Every entry stored in your browser, on your device. No server sync. No leaks. Nothing to breach.
One payment, forever
No subscription, no upgrade tier, no nag. If we shut down OneFileClub tomorrow, your file keeps working.
Data does not sync automatically between phone and desktop
This is a local-first app — everything stays on the device you logged it on. To use it on both phone and desktop, use the built-in JSON or CSV export on one device and import on the other when you want to keep them in step.
Every view, light and dark.
A look at every screen across both themes — your tracker, populated.
Questions
Real answers, no fine print.
Inverter integration?+
No — most inverters publish daily kWh on their app/portal. Type the number; the file lives forever, with or without the manufacturer.
Battery + EV charging?+
Battery SoC end-of-day tracked. EV charging adds to consumption — type the figure.
Where is my data stored?+
Locally, in your browser, on your device. Nothing is sent to OneFileClub or anyone else — there is no account, no cloud sync, no analytics.
Does it work offline?+
Yes. Once your personalised copy loads the first time, the entire tracker runs from a single HTML file. Airplane mode is fine.
What does 'personalised copy' mean?+
When you buy, OneFileClub stamps a private copy with your licence and deploys it to a unique URL just for you. You bookmark it, install it as an app, or save the file — and the file is yours, even if OneFileClub disappears tomorrow.
What is your refund policy?+
14 days, no questions asked. Email us, we'll process it and disable your private URL.
One payment.
A logbook that pays back.
We'll personalise a copy and email you a private link. Bookmark it, install it as an app, log today's generation.
14-day refund · No subscription
