System Architecture
System Block Diagrams
R.E.A.C.H. connects to the customer's existing remote solar power system. Field devices plug into R.E.A.C.H.'s USB outlets. The main control hub reads solar and battery metrics via INA260 current sensors and DCT voltage sensors, managed by an ESP8266 over I²C. A Particle Boron 404x handles LTE communication to the Grafana cloud dashboard.
Design Matrix — Table 1
Main Microcontroller Selection
The ESP8266 was selected as the main microcontroller with the highest weighted score of 0.28, driven by familiarity and low power consumption.
| Criteria | Weight | PIC18F47K42 | ESP8266 ✓ | Raspberry Pi | ESP32S3 |
|---|---|---|---|---|---|
| Cost | 0.2 | 0.29 | 0.30 | 0.15 | 0.26 |
| Processing Power | 0.05 | 0.10 | 0.30 | 0.40 | 0.20 |
| Availability | 0.05 | 0.02 | 0.01 | 0.96 | 0.06 |
| Familiarity | 0.3 | 0.22 | 0.32 | 0.17 | 0.30 |
| Clock Speed | 0.1 | 0.04 | 0.09 | 0.83 | 0.04 |
| Power Consumption | 0.3 | 0.31 | 0.33 | 0.06 | 0.30 |
| Score | 0.23 | 0.28 | 0.25 | 0.25 |
Design Matrix — Table 2
Transceiver Microcontroller Selection
The Particle Boron 404x scored highest at 0.37, driven by its LTE Cat M1 transmission type and strong power consumption rating.
| Criteria | Weight | Particle Boron ✓ | ESP32 S3 | Raspberry Pi | ESP8266 |
|---|---|---|---|---|---|
| Cost | 0.2 | 0.20 | 0.32 | 0.12 | 0.36 |
| Type of Transmission | 0.3 | 0.33 | 0.27 | 0.17 | 0.23 |
| Ease of Use | 0.2 | 0.25 | 0.15 | 0.30 | 0.30 |
| Support | 0.1 | 0.26 | 0.22 | 0.30 | 0.22 |
| Transmission Rate | 0.1 | 0.18 | 0.23 | 0.27 | 0.32 |
| Power Consumption | 0.3 | 0.45 | 0.20 | 0.10 | 0.25 |
| Score | 0.37 | 0.28 | 0.22 | 0.33 |
Design Matrix — Table 3
Transistor for Switching Selection
The Dual MOSFET Switch module scored highest at 0.44, primarily due to its high-side switching simplicity and temperature resistance.
| Criteria | Weight | Dual MOSFET ✓ | AO3400A | IRLZ44N |
|---|---|---|---|---|
| Loss | 0.2 | 0.33 | 0.34 | 0.33 |
| Cost | 0.25 | 0.36 | 0.29 | 0.35 |
| Availability | 0.15 | 0.33 | 0.33 | 0.33 |
| Temperature Resistance | 0.1 | 0.43 | 0.14 | 0.43 |
| High-Side Simplicity | 0.3 | 0.63 | 0.25 | 0.13 |
| Score | 0.44 | 0.28 | 0.28 |
Budget — Table 4
Cost Breakdown & Parts List
Updated Spring 2026 component list. INA219 replaced by Adafruit INA260 for higher accuracy. E-Ink display replaced the LCD module.
| Component | Qty | Unit Price | Total | Description |
|---|---|---|---|---|
| ESP8266 | 1 | $7.99 | $7.99 | Main microcontroller — controls outlets & sensors |
| Particle Boron 404x | 1 | $49.95 | $49.95 | LTE transceiver for cloud communication |
| YRDZXG Buck Converter | 1 | $9.99 | $9.99 | Steps down 12V battery to 5V for system power |
| ADS1115 Multiplexer | 1 | $3.96 | $11.89 | Allows ESP to interface with multiple analog sensors |
| Adafruit INA260 | 4 | $17.99 | $71.96 | High-accuracy current/power sensor (±1.5mA) |
| DCT-Electronics Voltage Sensor | 5 | $1.18 | $5.89 | Analog voltage divider sensors for line measurement |
| Female USB | 4 | $2.50 | $10.00 | USB-A outlets to deliver power to field devices |
| Dual MOSFET PWM Switch | 4 | $1.29 | $12.99 | Outlet switching modules controlled by ESP GPIO |
| Fuses | 4 | $0.20 | $9.00 | Resettable fuse protection per outlet circuit |
| Waterproof Enclosure | 1 | Free | Free | IP65-rated box housing all components |
| Waveshare E-Ink Display | 1 | $21.99 | $21.99 | Low-power local display for outlet states & metrics |
| Total Project Cost | $211.65 | |||
Hardware Photos
Component Photos
Key components used in the R.E.A.C.H. system. Replace the image filenames below with your actual photos.
