0. Safety and scope

• Use correctly rated protective devices, wire sizes, terminals and enclosures.
• Keep low-voltage logic physically separated from mains wiring.
• Use strain relief, insulation, earthing and flame-retardant materials.
• Confirm balcony load capacity, wind loading and panel anchoring.
• Do not energize an incomplete or uncovered assembly.

1. Gather the components

The original prototype cost was approximately BGN 700. Prices, availability and required certifications vary by country.

2. Configure Arduino IDE and test the ESP32

1. Download and install Arduino IDE.
2. Open File → Preferences and add this Board Manager URL:
   https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
3. Open Tools → Board → Board Manager, search for esp32 and install the Espressif Systems package. The original build used version 2.0.11; newer versions may require library updates.
4. Connect the ESP32 with a data-capable USB cable. Select Tools → Board → NodeMCU-32S and choose the correct COM port.
5. Upload the LED test below. A blinking onboard LED confirms that the board, USB driver and toolchain are working.

void setup() {
  pinMode(2, OUTPUT);  // Onboard LED
}

void loop() {
  digitalWrite(2, HIGH);
  delay(500);
  digitalWrite(2, LOW);
  delay(500);
}

3. Configure the JSY-MK-194T energy meter

The prototype changes the meter communication speed from 9600 baud to 38400 baud before loading the final router firmware.

1. With the assembly unpowered from mains, connect the meter’s low-voltage communication pins to the ESP32 according to the diagram below.
2. Download and upload the baud-rate conversion sketch.
3. Run the sketch for several seconds. Power down the low-voltage setup before changing wiring.
4. Use 38400 baud in the final firmware configuration.

4. Install the libraries and program the router

1. Download the library archive and extract its contents into your Arduino sketchbook libraries directory, normally C:UsersYourNameDocumentsArduinolibraries.
2. Download and open Solar_router.ino in Arduino IDE.
3. Set the Wi-Fi SSID and password in the firmware before uploading.
4. Set setTimeOffset for your local UTC offset. The original Bulgarian installation uses UTC+3 in summer and UTC+2 in winter; daylight-saving adjustment is manual.
5. Compile and upload the firmware to the ESP32.

5. Print and assemble the enclosure

1. Download the two enclosure files and print them from flame-retardant, UL-rated PETG or another material approved for the intended environment.
2. Install the M3 heat-set inserts and mount the low-voltage electronics securely.
3. Maintain clearance, insulation and physical separation between low-voltage and mains-voltage sections.
4. Have a qualified electrician complete and verify the mains wiring using the assembly diagram.
5. Inspect every terminal, strain relief and protective earth connection before closing the enclosure.

6. Install and commission the system

1. Panels: choose mounting hardware for the actual balcony or structure. Two standard panels can add roughly 50 kg of static load before wind and snow loads are considered. Obtain structural approval where required.
2. Microinverter: mount it in a ventilated location protected from direct sun and rain, following the manufacturer’s instructions.
3. Router: mount the closed enclosure securely, with the display at a readable height and suitable access for service.
4. Current transformer: the clamp orientation determines the sign of measured power. In the original installation, its arrow points toward the grid input. Verify direction from live readings during commissioning.
5. Functional test: start with low available solar power, confirm measurement polarity, then verify that routed power increases smoothly without exporting energy.

Do not commission the mains side alone unless you are qualified and legally permitted to perform this work.

7. Use the local web interface

After startup, the OLED displays the IP address assigned by your Wi-Fi router. Enter that address in a browser on the same local network.

• Force Mode: manually activates the relay for testing or override.
• Clock On/Off: enables scheduled operation, for example during a lower-cost electricity tariff.
• Screen On/Off: controls the OLED display.
• Time settings: configure the scheduled start time and UTC offset.
• OTA update: open http://<device-ip>/update to upload a newly compiled .bin firmware file.

8. Final checks

• Enclosure closed, secure and correctly labelled
• All mains work inspected and tested by a qualified electrician
• Measurement direction and power values verified
• Web interface reachable from the local network
• Relay, schedule, display and OTA page tested
• Surplus routing verified under gradually increasing solar production

Once these checks pass, monitor the system closely during its first operating days and periodically inspect terminals, temperature and mounting hardware.