🌦️ RS485 Weather Station – Custom Integration (CET & GPS)(Elsner / PEHA / Eltako )

Share your Projects! Custom Integrations
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Elsner OEM or Peha meteo
Elsner OEM or Peha meteo268Ă—235 35 KB

Wanted to share this one because I think it’s underrated: a professional
RS485 weather station that measures outdoor temperature, wind speed,
rain, and — the part I really like — brightness from three separate
directions (east, south, west), which makes automating blinds/shutters
based on actual sun exposure per façade way more accurate than a single
brightness sensor ever gives you.

Why it’s worth a look

This is genuinely commercial/professional-grade hardware — the kind of
thing you’d normally see mounted on office buildings — not a hobbyist
sensor:

  • :thermometer: Outdoor temperature, -40°C to +80°C
  • :dashing_away: Electronic (no moving parts) wind measurement, 0–35 m/s — works
    reliably in hail, snow and sub-zero temps, unlike cheaper mechanical
    anemometers that can freeze up
  • :sun: Three independent brightness sensors (east / south / west), 0–99,000
    lux — proper per-façade sun tracking for shading automation
  • :cloud_with_rain: Heated rain sensor (dries itself quickly, no false triggers from
    morning dew or fog)
  • :one_o_clock: Some versions add GPS: UTC time sync plus live sun azimuth/elevation
  • Sends fresh readings once per second

The Home Assistant side

The station talks RS485/serial,
I wrote a small custom integration
for it that:

  • connects over a cheap RS485-to-USB dongle,
  • automatically figures out which version of the data format your unit
    sends,
  • and turns it into clean, ready-to-use sensors (temperature, wind, sun Ă—3,
    rain, daylight, and more on the GPS version) — no manual setup of
    templates or anything fiddly.

Setup is just:

sensor:
  - platform: elsner
    name: weather_station
    serial_port: /dev/ttyUSB0

…and the sensors appear on their own.

GitHub (integration + docs): GitHub - v12345vtm/Elsner-Meteo_peha: Homeassistant custom component for Elsner P03/3 P04/3 · GitHub

The repo also includes a small Windows tool to test the station directly
over the RS485-to-USB dongle (handy to confirm your wiring works before
touching Home Assistant), plus an Arduino sketch that can simulate the
station if you want to try the integration before your sensor even arrives.

Feedback welcome

I’ve been running this on the Elsner-branded unit myself. If anyone has the
Eltako or PEHA version and tries it, I’d genuinely like to know it works
for you too — happy to help troubleshoot if something looks off.

it’s sold under at least 3 brand names

Same hardware, different label
Elsner
Peha
Eltako

So if you’ve been eyeing the PEHA version at €1000, the Elsner-branded one
appears to be the same sensor for less than half the price. For what you
get (3-way brightness, heated rain sensor, industrial housing, IP44), €400
is genuinely competitive against pricier all-in-one weather stations on the
market that offer less directional detail.

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