1. Why monitoring is free, forever

Cloud infrastructure is genuinely cheap. Cloudflare gives us a free tier that’s ample for tens of thousands of customers. The real cost of running Sentinel isn’t hosting — it’s engineering hours, and those are paid for by Solar Tech Support’s diagnostic and remedial work. The monitoring app is the funnel. The repair work is the business.

That dynamic only works if monitoring is genuinely free. The moment we put it behind a £4.99/month paywall like other monitoring apps, the customer doesn’t install Sentinel, doesn’t catch the fault, doesn’t ring us. Everybody loses. So we’re happy to eat the hosting cost — it pays for itself many times over in lead flow.

If you’re a sceptical engineer reading this and want to check our cost claims: a back-of-envelope per-customer cost on Cloudflare Workers + Durable Objects + R2 storage runs to roughly £0.02 / month / customer at the Live tier (no history) and £0.06 / month / customer at the Trend tier (12-month rolling Parquet rollups). The £1/mo Trend price covers that ~17x over. The margin pays for incident response, occasional engineering on the agent, and the times an engineer has to spend an hour helping a customer get the agent installed.

2. Why we’d rather you get two other quotes

When Sentinel spots a fault and you ring STS, we’ll quote you for the fix. Then we’ll suggest you get two other quotes from independent installers before deciding.

This isn’t fake humility. It’s self-interest. If you compare three quotes and pick ours, you bought with confidence and you’ll be a happy customer who tells their neighbours. If you pick a competitor’s quote because they’re cheaper or faster or you preferred their engineer, fair enough — that fault would have stayed undiagnosed without Sentinel, so we’ve still done the customer a favour, and the next fault you spot you might give us another go. Either way, you’re better off than you were when you had no monitoring at all.

The alternative business model — “you spotted the fault with our app, you have to use us for the repair” — is what the solar industry has been doing for two decades. It’s why so many customers don’t trust solar installers. We’d rather opt out of that pattern entirely.

3. Why £1 for history, not £5 or £10

Most monitoring SaaS prices by “how much pain you’ll tolerate” rather than “what does it cost us to provide.” That’s how you end up paying £200/year for a colour graph of your own solar production.

We price by cost-plus-thin-margin. £1/month covers the R2 storage cost of 12 months of 1-minute-rollup telemetry plus a generous margin for engineering time. £2/month for the Engineer tier (cell-level data, DC force-charge, advanced register access) is the same calculation with a slightly bigger margin to cover the support burden when power users break things and need help.

If we ever need to put prices up, you’ll know 60 days in advance and you can cancel at any time. We’ll never trap you in a year-long contract or tie features to a renewal cliff.

4. What we’ll never do with your data

• We’ll never sell it. Not anonymised “market research”, not aggregated “industry insights”, not bundled into a research data set for some battery manufacturer’s ML model. The data your inverter generates is yours. Full stop.
• We’ll never advertise to you in-app. No banner ads, no promoted “recommended installer” cards, no third-party tracking. The dashboard’s only ads are the Solar Tech Support links — and those are written so you know exactly what they are.
• We’ll never lock you out of your own data. CSV export of every reading we’ve ever stored, downloadable at any time, even after you cancel.
• We’ll never share it with GivEnergy, even if they ask. The administration is what made this product necessary; we’re not handing over anything to the entity (or whoever buys the assets) that left their customers stranded.
• We’ll never email you marketing junk. Transactional emails only — fault alerts, billing receipts, security notifications. No newsletter, no “here’s 10% off,” no “we noticed you haven’t checked your dashboard in a while.”

5. What we will do that’s less obvious

• Push you toward fixing things you don’t need fixed. Wait, no. We won’t do that. The fault knowledge base is written to help you decide what’s genuinely a problem and what’s just the inverter doing its job. A fault that says “sustained export at G98 limit” isn’t a fault — it’s your system working perfectly on a sunny day.
• Be open about the limits. If a feature isn’t ready, the page will say so loudly. The Sentinel Stick is a good example — we could have launched a marketing page that pretended the stick was for sale next week. Instead it says “coming soon, late 2026”.
• Recommend competitors when they’re a better fit. If your inverter isn’t GivEnergy yet — say you’ve got a FoxESS or Solis system — we’ll point you to dedicated tools for those manufacturers until our multi-inverter support ships. Sentinel exists for the GivEnergy gap; we’re not trying to be everything to everyone.

6. Who pays for this and how the books balance

Sentinel is a wholly owned product of RVTC LTD, a UK limited company. The same company runs Solar Tech Support, a solar diagnostic and repair service that has been operating since 2019, and Alectrona, a solar installation company. The accounts are public — Companies House filing 14XXXXXX.

Sentinel runs at a small loss in isolation. The loss is more than offset by the engineer-services revenue Sentinel drives into STS. We don’t have outside investors and we’re not trying to grow Sentinel to be acquired. The aim is for it to be a slow-but-stable lead source for STS for the next 10+ years.

If RVTC LTD ever gets sold or wound up, we’ve committed in the privacy policy to a 30-day notice window during which all telemetry data is exported and deleted — your data doesn’t get bundled into an acquisition.