Self-Hosted Solar Energy Monitoring: Sunsynk vs Solaranzeige vs PVOutput Integration

Introduction

Residential solar installations have surged globally, with millions of homes now generating their own electricity. Yet most solar inverters ship with proprietary cloud monitoring that locks your own energy data behind a manufacturer’s portal — often with limited historical access, no API, and the risk of service discontinuation if the company goes under.

Open-source solar monitoring platforms solve this by pulling data directly from your inverter (via Modbus, RS485, or WiFi), storing it locally, and providing customizable dashboards. In this guide, we compare three self-hosted approaches: Sunsynk (Python library for Deye/Sunsynk inverters), Solaranzeige (German-developed monitoring dashboard), and PVOutput integration (community-driven data aggregation).

Comparison Table: Sunsynk vs Solaranzeige vs PVOutput

Sunsynk: Python Library for Deye/Sunsynk Inverters

Sunsynk is a Python library that reads real-time data from Deye and Sunsynk hybrid inverters via Modbus RTU (RS485) or Modbus TCP (WiFi dongle). It exposes inverter metrics — solar generation, battery state of charge, grid import/export, load consumption — as sensors in Home Assistant through its official addon.

The library supports over 200 Modbus registers covering every aspect of the inverter operation, from basic power readings to advanced battery management system (BMS) data. It also provides write capability for controlling inverter settings like charge/discharge schedules and work modes.

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# Home Assistant configuration for Sunsynk
# configuration.yaml
sensor:
  - platform: sunsynk
    port: /dev/ttyUSB0
    slave_id: 1

# Docker deployment (standalone without HA)
# docker-compose.yml
version: '3'
services:
  sunsynk:
    image: kellerza/sunsynk:latest
    container_name: sunsynk
    devices:
      - /dev/ttyUSB0:/dev/ttyUSB0
    environment:
      - INVERTER_PORT=/dev/ttyUSB0
      - INVERTER_SLAVE_ID=1
      - MQTT_HOST=mosquitto
      - MQTT_PORT=1883
    restart: unless-stopped

The library outputs data to MQTT by default, making it easy to integrate with Node-RED, Grafana, or any MQTT-compatible platform. For Home Assistant users, the official addon provides one-click setup with automatic sensor discovery.

Solaranzeige: German Solar Monitoring Dashboard

Solaranzeige is a comprehensive solar monitoring web application developed in Germany, where residential solar adoption is among the highest globally. It reads inverter data via Modbus TCP or RS485 and stores it in InfluxDB for Grafana visualization.

The platform includes pre-built Grafana dashboards with German and English translations, showing daily production curves, monthly totals, self-consumption ratios, and battery charge/discharge patterns. Alerting is configured through email notifications for abnormal conditions like zero production during daylight hours.

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# Installing Solaranzeige via Docker
# Clone the repository
git clone https://github.com/DeBaschdi/docker.solaranzeige.git
cd docker.solaranzeige

# Configure your inverter in config/solaranzeige.yaml
# Edit and start:
docker compose up -d

# Access the Grafana dashboard at http://your-pi:3000
# Default credentials: admin / admin

Solaranzeige supports a wide range of inverters through its modular driver system: SMA, Fronius, Kostal, SolarEdge, Huawei, and any inverter supporting the SunSpec Modbus standard. The modular architecture means new inverter drivers can be added without modifying the core application.

PVOutput Integration: Community Energy Aggregation

PVOutput.org is a free community platform for sharing and comparing solar generation data. While the main PVOutput service is cloud-hosted, the data uploader tools are fully open-source and self-hostable. PVOutput serves a different purpose than Sunsynk or Solaranzeige — it is about community benchmarking rather than private monitoring.

The typical setup involves running a local uploader script that pushes generation data to PVOutput.org at regular intervals. You get access to system ranking, efficiency comparisons with nearby systems, and weather-corrected performance metrics. Many users run Solaranzeige or Sunsynk for local monitoring AND upload to PVOutput for community comparison.

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# Example: PVOutput upload script for Sunsynk inverters
# Save as pvoutput_upload.py and run via cron every 5 minutes
import requests
import json

API_KEY = "your_pvoutput_api_key"
SYSTEM_ID = "your_system_id"
INVERTER_IP = "192.168.1.100"

# Fetch current generation from inverter Modbus
# (implementation depends on your inverter model)
data = fetch_inverter_data(INVERTER_IP)

# Upload to PVOutput
headers = {
    "X-Pvoutput-Apikey": API_KEY,
    "X-Pvoutput-SystemId": SYSTEM_ID,
}
payload = {
    "d": data["date"],
    "t": data["time"],
    "v1": data["energy_generated"],
    "v2": data["power_generated"],
    "v5": data["temperature"],
    "v6": data["voltage"],
}
requests.post("https://pvoutput.org/service/r2/addoutput.jsp",
               headers=headers, data=payload)

PVOutput supports custom uploaders for any inverter brand — if your inverter can export data (even via CSV), you can build a PVOutput uploader for it. The platform has grown to over 60,000 registered systems worldwide.

Why Self-Host Your Solar Monitoring?

Solar inverters typically last 10-15 years, but cloud monitoring services may not. Several inverter manufacturers have discontinued their cloud platforms, leaving customers with “dumb” inverters that still generate power but provide no data. Self-hosted monitoring ensures you control your data for the full lifespan of your installation.

Local monitoring also provides sub-second data resolution that cloud services rarely offer. When debugging a production dip, having per-second power readings lets you correlate with cloud cover, appliance usage, or inverter throttling. Our home energy monitoring guide covers additional platforms for whole-home energy tracking.

For home automation integration, see our Home Assistant comparison to build automations around solar production — like running high-consumption appliances during peak generation hours. For broader IoT data pipelines, our MQTT broker comparison covers the transport layer that Sunsynk uses for data output.

Hardware Setup and Connectivity Options

Connecting your inverter to a monitoring platform requires understanding the available communication interfaces. Here is a practical guide to getting your inverter talking to your monitoring server:

RS485 (Modbus RTU): The most reliable and widely supported connection method. Most inverters expose an RS485 port through an RJ45 connector — the same physical connector as Ethernet, but carrying serial data on pins 7 (A/+) and 8 (B/-). You need a USB-to-RS485 adapter (FTDI-based adapters are most reliable, $8-15). Cable distance can reach 1200 meters with proper termination, making this ideal for inverters installed in garages or outbuildings far from your server.

WiFi Dongle (Modbus TCP): Many modern inverters ship with a WiFi dongle that connects the inverter to your home network. The dongle typically exposes a Modbus TCP server on port 502. This is the easiest setup — no wiring required — but WiFi reliability can be an issue. If your inverter drops off the network during peak solar hours, you lose data for that period.

Direct WiFi (ESP32 Bridge): For inverters without built-in WiFi, an ESP32 running a Modbus-to-MQTT bridge firmware provides a wireless monitoring solution. The ESP32 connects to the inverter RS485 port on one side and your WiFi network on the other, translating Modbus registers to MQTT topics. This combines the reliability of RS485 with the convenience of WiFi, and costs under $10 in parts.

Multiple inverters, single monitoring server: Both Sunsynk and Solaranzeige support multiple inverter connections. Sunsynk can read from multiple Modbus ports simultaneously. Solaranzeige supports multiple inverter drivers configured in its YAML configuration. When monitoring multiple inverters (common in larger residential installations with east/west arrays), ensure your server has enough USB ports or use a USB hub with adequate power delivery. Each RS485 connection requires its own USB-to-RS485 adapter — you cannot share one adapter across multiple inverters.

Data integrity considerations: RS485 communication is susceptible to electrical noise from the inverter itself. Use shielded twisted-pair cable for RS485 runs, connect the shield to ground at ONE end only (to avoid ground loops), and enable the 120-ohm termination resistor at the end of the bus. If you experience intermittent data dropouts, add a ferrite bead to the RS485 cable near the USB adapter.

FAQ

Which inverter brands are supported?

Sunsynk specifically supports Deye and Sunsynk branded inverters (they are the same hardware). Solaranzeige supports SMA, Fronius, Kostal, SolarEdge, Huawei, and any Modbus/SunSpec-compatible inverter. PVOutput integration works with any inverter that can export data, either natively or through a third-party uploader.

Do I need an internet connection for local monitoring?

No — Sunsynk and Solaranzeige both work fully offline on your local network. The inverter communicates over RS485 or local WiFi. PVOutput requires internet access since it uploads to the cloud service, but the data uploader can buffer data during outages.

Can I control my inverter settings through these tools?

Sunsynk provides write access to inverter registers, allowing you to change charge/discharge schedules, work mode, and battery settings programmatically. Solaranzeige is read-only for monitoring. Always exercise caution when writing to inverter registers — incorrect values can affect system operation.

How do I connect to my inverter if it only has a manufacturer app?

Most modern inverters have an RS485 port (RJ45 connector) or a WiFi dongle. You need a USB-to-RS485 adapter (under $10) to connect the inverter to a Raspberry Pi or server. Check your inverter manual for the Modbus pinout — it is usually pins 7 and 8 on the RJ45 connector.

What is the difference between Modbus RTU and Modbus TCP?

Modbus RTU uses RS485 serial communication (wired, up to 1200m). Modbus TCP uses Ethernet/WiFi (network-based). Sunsynk and Solaranzeige support both. If your inverter has a WiFi dongle, it likely uses Modbus TCP. If it has an RS485 port, it uses Modbus RTU. The data is identical — only the transport differs.

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