Carbon — carbon.html

One question, answered at the top: is now a good time to run a load. Everything below is the working. Needs nothing beyond a region setting — the data is the free UK Carbon Intensity API, no key required.

Down the page

Verdict. A coloured card with a timing word, a heading and a sentence explaining it. In daylight with spare solar it reads RUN NOW and names the spare kilowatts; with a clean grid and no surplus it reads ANYTIME; otherwise it names the cleanest window ahead. The advice ranks spare solar first, then a genuinely clean grid, then waiting for the cleanest window in the next sixteen hours.

Three tiles. Grid carbon for your region in gCO₂/kWh with a plain-English band, solar now with the battery percentage beside it (a dash after dark rather than a zero), and the import rate with a note on how it moves through the day. Daylight alone does not make it RUN NOW: solar the house and battery are already using is not spare.

Grid carbon, next 24 hours. A half-hourly forecast bar chart, greener meaning cleaner, with the current half-hour outlined and the cleanest upcoming window called out.

Where the grid’s power is coming from. The live generation mix as labelled bars, ordered by share. Categories at zero drop out, so the list is shorter after dark.

How this is worked out. The reasoning in full, including the part that matters most: on a flat tariff the cost is much the same whenever you run, so carbon and solar drive the timing rather than price.

Where the numbers come from

carbonAdvisor. The plugin fetches your region’s intensity, the 48-hour forecast and the generation mix, caches them for ten minutes server-side, and combines them with the live solar surplus and tariff (from the energy plugin, when present) before handing over a recommendation.

Refresh

Every 60 s, with the header counting down to the next one. The carbon data behind it only moves every ten minutes because of the server-side cache. A fetch landing just after a plugin restart retries quickly instead of waiting out the full poll.

What you can do here

Read the verdict and follow the link to the Energy page. No controls.

Worth knowing

• The region matters. Carbon intensity is regional, and yours may be considerably cleaner or dirtier than the national figure. Set it under Configure.
• The advice deliberately prefers spare solar over a clean grid even when the grid is very clean, because spare solar is free and would otherwise be exported for pennies.
• On a flat tariff the page is about carbon, not money.