Features → When it cannot see

When it cannot see your solar

Things go quiet. An inverter reboots for a firmware update, a router restarts, the machine running the agent gets unplugged by someone hoovering. What Sunplug does then is the same in every case, and it is the least convenient of the available options.

An old reading is not a small error

The tempting behaviour is to carry on with the last number you saw. It feels gentle — the sun was there a minute ago, it is probably still there.

But a solar surplus figure is a statement about right now, and it decays fast. A house exporting 4 kW when the agent went quiet may have put an oven and a kettle on since. Charging two cars on the strength of a reading from twenty minutes ago is not a small error in one direction; it is buying grid power at peak rate while believing you are charging on sunshine.

So after about five minutes without a fresh reading, Sunplug stops treating the number as true and takes the cars to zero. Not "carries on carefully" — to zero.

Why it says so out loud

The decision log names it: site data stale, failing safe, with how old the reading actually is. This matters more than it looks, because the failure it prevents is the quiet kind.

An engine that has stopped is obvious — nothing is charging and you notice. An engine that is ticking along healthily, making decisions every thirty seconds, and failing every car to zero because it cannot see anything is not obvious from the outside. Everything looks alive. The only thing that distinguishes it is the reason on each decision, which is why the reason is written down.

What still works

Losing sight of your solar does not mean losing everything.

• Charge windows still fire. If you have told Sunplug to top the cars up from the grid overnight, that does not depend on knowing what the sun is doing.
• Blockouts still hold. Hours you have forbidden stay forbidden.
• Your car's own schedule is still there. Sunplug normally overrides it, on the reasoning that the car's schedule exists as the fallback for Sunplug being down rather than as a second opinion while it is up. If Sunplug really is down, that fallback is exactly what it was for.

When it comes back

Readings resume, and the ordinary restart delay applies — a car does not jump straight back to full current, for the same reasons it does not chase clouds. Nothing needs restarting and nothing needs re-pairing; the gap simply shows in the history as a gap, which is what it was.

Different equipment goes stale at different speeds

Five minutes is right for hardware read locally. It answers every thirty seconds, but a real home network drops the odd reading, and one or two missed is not a dead feed. A cloud source is judged on its own reporting interval instead: two of them, never more than fifteen minutes.

This is a large part of why reading your own hardware is worth the trouble: thirty seconds tells you a cloud is passing while it passes; five minutes tells you afterwards.

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