☀️ Solar Track — Dual-Axis Solar Tracker

An automated dual-axis sun-tracking system that keeps a solar panel pointed at the sun for maximum energy capture, using four LDRs and two servo motors in a simple closed loop.

🔆 How it works

Four LDRs sit in a "+" shaped holder with opaque walls between them, so each light sensor only sees light from its own quadrant. When the panel drifts off-axis, the walls shadow one side and the four readings diverge — the controller then nudges the servos until opposing sensors read equal (i.e. the panel faces the sun head-on).

                 TOP
             TL  |  TR
            -----+-----      <- opaque "+" dividers
             BL  |  BR
                BOTTOM

  Azimuth   (base servo)  : LEFT (TL+BL)  vs  RIGHT (TR+BR)
  Elevation (panel servo) : TOP  (TL+TR)  vs  BOTTOM (BL+BR)

• Base servo (azimuth) rotates the whole assembly left/right, comparing the two left LDRs against the two right LDRs.
• Panel servo (elevation) tilts the panel up/down, comparing the two top LDRs against the two bottom LDRs.
• A deadband (TOLERANCE) stops the servos hunting/jittering once the panel is roughly aligned, and at night the tracker stops chasing noise and eases back to a home position for the next sunrise.

🧰 Bill of materials

Qty	Part
1	Arduino Uno / Nano (or any AVR board)
2	Servo motors — one for the base (azimuth), one for the panel tilt (elevation)
4	LDRs (photoresistors)
4	10 kΩ resistors (one per LDR, voltage divider)
1	"+" LDR holder with opaque dividers (3D-printed or card/foam)
1	External 5 V supply for the servos (recommended)
—	Small solar panel + mount/holder, jumper wires

🔌 Wiring

LDRs — each as a voltage divider (more light → higher reading):

5V ── LDR ──┬── A0..A3 (analog in)
            └── 10kΩ ── GND

LDR	Analog pin
Top-left (TL)	A0
Top-right (TR)	A1
Bottom-left (BL)	A2
Bottom-right (BR)	A3

Servos — signal to D9 (base/azimuth) and D10 (panel/elevation). Power both servos from an external 5 V supply, not the Arduino's 5 V pin (two servos can draw enough stall current to brown out the board). Tie the servo supply ground to the Arduino ground (common ground).

▶️ Use

1. Open Solar_Tracker/Solar_Tracker.ino in the Arduino IDE.
2. Upload to your board, then open the Serial Monitor at 9600 baud to watch the four LDR readings and servo angles.

🎛️ Tuning (top of the sketch)

Constant	What it does
TOLERANCE	Deadband — raise it if the servos jitter, lower for tighter tracking.
STEP / UPDATE_MS	How fast/smooth it moves.
SAMPLES	Analog reads averaged per LDR (noise smoothing).
AZ_MIN/MAX, EL_MIN/MAX	Servo travel limits — set to your servo's real range.
AZ_DIR, EL_DIR	Flip +1→-1 if an axis tracks the wrong way.
LDR_BRIGHT_IS_HIGH	Set false if your dividers are wired the opposite way.
NIGHT_LEVEL, RETURN_HOME_AT_NIGHT	Night behaviour + home pose.

First run: if a servo drives away from the light, flip that axis's *_DIR. If it never settles, increase TOLERANCE.

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_{Part of @ramuroy's embedded systems work.}