A 3D printable dual-axis solar tracker for maximizing photovoltaic energy yield
Sunchronizer automatically tracks the sun's position throughout the day to keep your solar panels optimally aligned, with measured gains of about +12% vs. single-axis tracking and +144% vs. static east/west references.
Left GIF: Sx variants (S1/S2, single-axis) · Right GIF: Dx variants (D1/D2, dual-axis)
Working with balcony power plants in Germany, I wondered how to maximize solar panel efficiency. The solution: Sunchronizer – a fully automated, 3D-printable solar tracker available in single-axis and dual-axis configurations.
The system uses a linear actuator and geared motor to continuously orient your solar panels toward the sun, significantly improving daily energy yield.
- Microcontroller: ESP32-S3
- Firmware: ESPHome (open-source, HomeAssistant-compatible)
- Tracking Methods: Sun position calculation (via GPS or HomeAssistant), compass-based orientation verification
- Flexibility: Works with HomeAssistant or standalone via GPS receiver
- Power: 12V/3A supply (USB-C Power Delivery recommended)
| Model | Capability | Best For |
|---|---|---|
| S2 | Elevation angle tracking (single-axis, 2nd generation) | Refined single-axis builds with lower complexity |
| D2 | Elevation + azimuth tracking (dual-axis, 2nd generation) | Maximum efficiency, most refined dual-axis variant |
- Firmware & Configuration - Detailed firmware configuration guide and pre-built binaries
- Web Installer - Flash the latest release directly from a Chromium browser
- Public Web Installer - Browser-based installer hosted on GitHub Pages
- Latest Firmware Release - Download current firmware binaries from release assets
- Firmware Documentation - Comprehensive ESPHome firmware documentation
- Prototype Development History - Photo gallery and timeline of mark1-mark4 plus PCB v1.3
- Measurement Analysis Overview - Daily performance results with links to detailed analysis reports
- FAQ - Frequently asked questions about assembly, firmware, performance, and operation
- Full Wiki - Complete project documentation
- Material List - Components and BOM
- Want to flash immediately? → Use the Web Installer or download from Latest Release Assets
- Want to customize configuration? → Review firmware configuration guide
- Need detailed setup instructions? → Check Wiki: Firmware Section
- Want real measurement data and performance comparisons? → Open Measurement Analysis Overview
- ESP32-S3 XIAO - Dual-core processor with WiFi
- Dual H-Bridge - Controls elevation and azimuth motors
- 12V/3A Power Supply - USB-C Power Delivery compatible
| Sensor | Purpose | Details |
|---|---|---|
| BNO085 IMU | Elevation & Heading angle measurement | 9-DOF accelerometer, gyro, magnetometer |
| DS3231 RTC | Precise timekeeping | Independent of network connection |
| GPS Module (optional) | Position & time retrieval | Enables standalone operation |
- UP/CCW Button - Lift panel or rotate counter-clockwise
- DOWN/CW Button - Lower panel or rotate clockwise
- Additional controls via web interface and HomeAssistant
📖 Full Electronics Documentation
STL files and detailed build information available at:
| Variant | Nerdiy.de | Printables.com | Cults3d.com |
|---|---|---|---|
| Nerdiy.de | — | — | |
| Sunchronizer S2 (single-axis, 2nd gen) | — | Printables | Cults |
| Nerdiy.de | — | — | |
| Sunchronizer D2 (dual-axis, 2nd gen) | — | Printables | Cults |
- Framework: ESPHome - Open-source ESPHome project
- Integration: Native HomeAssistant support with custom web interface
- Source: Fully open-source configuration files included
The firmware depends on two ESPHome external components that are fetched from GitHub during the build:
- 📋 Firmware Configuration Guide - Comprehensive configuration reference
- 🔧 Firmware Configuration Details - PCB v1.3 configuration specifics
- 🔧 Wiki: Firmware Section - Detailed technical documentation
If you find this project valuable, consider supporting its development:
Every coffee helps fund research, development, and documentation! ☕
~~Sunchronizer S1 (Single-Axis)~~ ⚠️ deprecated — use S2 instead
~~Sunchronizer D1 (Dual-Axis)~~ ⚠️ deprecated — use D2 instead
Coming soon — photos and technical drawings to be added.
Sunchronizer S2 (Single-Axis, 2nd gen)
Coming soon — photos and technical drawings to be added.
Sunchronizer D2 (Dual-Axis, 2nd gen)
Coming soon — photos and technical drawings to be added.
This project uses three separate licenses depending on the type of content:
All STL files are licensed under: CC BY-NC-ND 4.0 (Attribution – Non-Commercial – No Derivatives)
- ✅ Print for personal use
- ✅ Share photos of your build with attribution
- ❌ Sell the STL files
- ❌ Sell printed parts or assembled trackers
- ❌ Publish modified/remixed versions of the STL files
All documentation, guides, diagrams, and written content are licensed under: CC BY-NC-SA 4.0 (Attribution – Non-Commercial – Share Alike)
All firmware configuration files and software code are licensed under: GNU Affero General Public License v3.0
- ✅ Use, study, and modify freely
- ✅ Commercial use allowed
- ❌ Modifications must be published under AGPL v3.0
See FAQ.md for a plain-language explanation of what you can and cannot do.
- DS3231 RTC Component for ESPHome - ESPHome external component used by the firmware
- BNO085 RVC Component for ESPHome - ESPHome external component used by the firmware
- ESPHome Official Documentation
- Home Assistant - Smart home integration platform
- Nerdiy.de Blog - Project blog and store
For answers to common questions about assembly, firmware, hardware variants, GPS setup, and more, see the FAQ.
Last Updated: April 2026
