Current solar output: how to see what your panels do right now

"What are the panels doing right now?" sounds like the easiest question in home solar. It isn't, because the obvious answer — the inverter app — has two problems: it usually trails reality by minutes (cloud passes, app still celebrates), and it only shows production. For every practical decision you actually need the net flow: production minus whatever the house is eating at that moment.

Production vs net flow

Your panels making 2.4 kW means nothing on its own. If the oven and the dryer are pulling 3.1 kW, you are — despite the sunshine — buying 0.7 kW. The number that decides whether now is a good moment to start another appliance is the one your digital meter computes continuously: net offtake or net injection, updated every second, on the P1 port.

That port is the most underrated feature of the whole smart meter rollout. A €30 dongle (HomeWizard's is the one I use) puts the live reading on your WiFi, and from there it's yours — no cloud required, no subscription, one-second resolution.

From number to glance

You can watch the dongle's app, but live numbers you must fetch are live numbers you'll stop fetching (the same reason inverter apps go unopened). The trick is turning the net flow into something ambient. My version: an €8 LED strip running WLED with a usermod that polls the P1 dongle — green and filling up when injecting, red when buying. The strip is the answer to "can I start the dryer?" from across the room, latency about a second, cost about a lunch.

If you'd rather solder nothing: the WLED P1 Flasher writes the firmware to an ESP32 straight from your browser. Plug in strip, enter WiFi, done.

"Now" is half the picture

Live output answers whether this moment is green. It can't answer whether 15:00 will be greener — for that you want the production curve of the rest of the day, which is exactly what a solar forecast gives you (how to plan your day around it). And why all this glancing and planning is worth actual money — the gap between what injection pays and offtake costs — is spelled out in offtake vs injection.

Forecast at breakfast, light before every start button. Your meter already knows everything; the whole project is just making it show you.

P1 ports are standard on Belgian and Dutch digital meters (DSMR); elsewhere, check what your meter exposes. No affiliations — the tools here are free and the hardware is whatever your electronics shop sells.