Solar Power & Telemetry

I dedicated 2026 to updating this site, so let's talk about my home solar setup. I have a grid-tied 13.5kW AC system on the roof made up of 27 LONGi high-density solar panels running Hoymiles HMS microinverters. I don't have any battery storage since the electrical code around here doesn't really allow batteries in the home yet, so everything feeds right back into the grid.

I collect solar data from my panels in two different ways:

• Panel CT Clamps: Current Transformer (CT) sensors on each phase of my main breaker panel track whole-home power consumption and grid export.
• OpenDTU Interception: OpenDTU is an awesome open-source project that lets you catch sub-1GHz radio data broadcast straight from Hoymiles microinverters. I have a receiver running in my workspace that snags the radio transmissions directly off the roof in real time and pushes it straight to Home Assistant via MQTT over Wi-Fi. It works amazingly well.

I get asked a lot if I ever need to clean the panels. The short answer is: only in the winter. In hot, dry places, dust builds up and needs to be washed off. Not here. The only thing I ever have to deal with is heavy snow blocking the glass.

Normally, if the sun hits the dark panel surface, they warm up and most of the snow slides off on its own. But usually, I need to jump-start the process. I use a roof rake that won't scratch or damage the glass to pull down the first few feet of snow along the bottom edge of the roof. As soon as that dark blue/black panel glass is exposed to the sun, it starts heating up and melting the rest off. Of course, that usually only works when we get under 30–40cm of snow and the temp isn't parked below -10°C!