Greetings yall! I used Codex and Claude Code to help me write a control scheme for these OOYCYOO MPPT controllers one would easily find on Amazon or Ebay. I have long been frustrated by them, because they say in the description that they have RS485 functionality… but good luck getting any information about their protocols besides “RJ45 only for lcd display, $29.95 extra”. So I downloaded the firmware out of the controller and used AI to reverse engineer it.
You will need 1 RS485 to TTL converter per MPPT controller. I have two 100A working in parallel, so the yaml is set up for two. Pins 4/5 are the data lines (blue/blue white pair on ethernet cable). The other 6 conductors carry 12v! Use the USB ports to power your esp32.
Update your default settings, mine is set up for 8s lifepo.
substitutions:
device_name: ooycyoo-mppt-bridge
friendly_name: OOYCYOO MPPT Bridge
esphome:
name: ${device_name}
friendly_name: ${friendly_name}
esp32:
board: esp32dev
framework:
type: arduino
logger:
baud_rate: 0
# Explicitly load the domains used by the external component.
sensor:
binary_sensor:
switch:
button:
number:
api:
ota:
- platform: esphome
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
external_components:
- source:
type: local
path: components
# Use one UART and one automatic-direction RS485 transceiver per controller.
# These GPIO assignments are examples and must match the physical ESP32 wiring.
uart:
- id: mppt_1_uart
tx_pin: GPIO17
rx_pin: GPIO16
baud_rate: 9600
parity: NONE
stop_bits: 1
- id: mppt_2_uart
tx_pin: GPIO26
rx_pin: GPIO27
baud_rate: 9600
parity: NONE
stop_bits: 1
ooycyoo_mppt:
- id: mppt_1
uart_id: mppt_1_uart
# Safety default: keep false until settings and wiring have been verified.
poll_enabled: true
# Resend the requested settings when the controller is out of sync.
auto_resync: true
pv_off_voltage: 27.5
load_off_voltage: 21.4
load_on_voltage: 25.2
evening_hours: 20
interval_hours: 2
dawn_hours: 2
pv_voltage:
name: "MPPT 1 PV Voltage"
pv_current:
name: "MPPT 1 Estimated PV Current"
solar_power:
name: "MPPT 1 Estimated Solar Power"
battery_voltage:
name: "MPPT 1 Battery Voltage"
battery_current:
name: "MPPT 1 Charging Current"
battery_charging_power:
name: "MPPT 1 Battery Charging Power"
battery_temperature:
name: "MPPT 1 Battery Temperature"
battery_percent:
name: "MPPT 1 Estimated Battery Percent"
load_voltage:
name: "MPPT 1 Load Voltage"
load_current:
name: "MPPT 1 Load Current"
total_energy:
name: "MPPT 1 Total Energy"
pv_off_voltage_feedback:
name: "MPPT 1 Controller PV Off Voltage"
load_off_voltage_feedback:
name: "MPPT 1 Controller Load Off Voltage"
load_on_voltage_feedback:
name: "MPPT 1 Controller Load On Voltage"
evening_hours_feedback:
name: "MPPT 1 Controller Evening Hours"
interval_hours_feedback:
name: "MPPT 1 Controller Interval Hours"
dawn_hours_feedback:
name: "MPPT 1 Controller Dawn Hours"
load_path_fault:
name: "MPPT 1 Load Path Fault"
charge_path_fault:
name: "MPPT 1 Charge Path Fault"
settings_acknowledged:
name: "MPPT 1 Settings Acknowledged"
setting_update_pending:
name: "MPPT 1 Setting Update Pending"
setting_write_attempts:
name: "MPPT 1 Setting Write Attempts"
load_switch:
name: "MPPT 1 DC Load"
reset_button:
name: "MPPT 1 Reset Settings"
pv_off_number:
name: "MPPT 1 Requested PV Off Voltage"
load_off_number:
name: "MPPT 1 Requested Load Off Voltage"
load_on_number:
name: "MPPT 1 Requested Load On Voltage"
evening_number:
name: "MPPT 1 Requested Evening Hours"
interval_number:
name: "MPPT 1 Requested Interval Hours"
dawn_number:
name: "MPPT 1 Requested Dawn Hours"
- id: mppt_2
uart_id: mppt_2_uart
# Safety default: keep false until settings and wiring have been verified.
poll_enabled: true
# Resend the requested settings when the controller is out of sync.
auto_resync: true
pv_off_voltage: 27.6
load_off_voltage: 24.3
load_on_voltage: 24.8
evening_hours: 24
interval_hours: 0
dawn_hours: 0
pv_voltage:
name: "MPPT 2 PV Voltage"
pv_current:
name: "MPPT 2 Estimated PV Current"
solar_power:
name: "MPPT 2 Estimated Solar Power"
battery_voltage:
name: "MPPT 2 Battery Voltage"
battery_current:
name: "MPPT 2 Charging Current"
battery_charging_power:
name: "MPPT 2 Battery Charging Power"
battery_temperature:
name: "MPPT 2 Battery Temperature"
battery_percent:
name: "MPPT 2 Estimated Battery Percent"
load_voltage:
name: "MPPT 2 Load Voltage"
load_current:
name: "MPPT 2 Load Current"
total_energy:
name: "MPPT 2 Total Energy"
pv_off_voltage_feedback:
name: "MPPT 2 Controller PV Off Voltage"
load_off_voltage_feedback:
name: "MPPT 2 Controller Load Off Voltage"
load_on_voltage_feedback:
name: "MPPT 2 Controller Load On Voltage"
evening_hours_feedback:
name: "MPPT 2 Controller Evening Hours"
interval_hours_feedback:
name: "MPPT 2 Controller Interval Hours"
dawn_hours_feedback:
name: "MPPT 2 Controller Dawn Hours"
load_path_fault:
name: "MPPT 2 Load Path Fault"
charge_path_fault:
name: "MPPT 2 Charge Path Fault"
settings_acknowledged:
name: "MPPT 2 Settings Acknowledged"
setting_update_pending:
name: "MPPT 2 Setting Update Pending"
setting_write_attempts:
name: "MPPT 2 Setting Write Attempts"
load_switch:
name: "MPPT 2 DC Load"
reset_button:
name: "MPPT 2 Reset Settings"
pv_off_number:
name: "MPPT 2 Requested PV Off Voltage"
load_off_number:
name: "MPPT 2 Requested Load Off Voltage"
load_on_number:
name: "MPPT 2 Requested Load On Voltage"
evening_number:
name: "MPPT 2 Requested Evening Hours"
interval_number:
name: "MPPT 2 Requested Interval Hours"
dawn_number:
name: "MPPT 2 Requested Dawn Hours"
