Dual-Axis Solar Tracker DIY Part 2: Assembly & Sensor Wiring

Solar panel power output depends critically on orientation toward the sun. Direct sun exposure produces maximum voltage and current, while angular deviation causes dramatic current reduction despite stable voltage. Since power equals volts times amps, current loss directly reduces wattage. Optimal orientation requires facing south in the northern hemisphere and north in the southern hemisphere (toward the equator). When direct equator-facing installation is impossible, an east-west configuration with independently wired panels can optimize morning and afternoon sun capture, outperforming misaligned panels throughout the day.

Solar panel orientation significantly impacts annual energy production. South-facing slopes are optimal, providing maximum sun exposure throughout the day. East and west-facing slopes result in 17-20% less annual production compared to south-facing orientations. North-facing installations are strongly discouraged as they produce dramatically less energy, with winter production potentially only one-third of south-facing panels. The low sun angle in northern orientations causes severe shading issues throughout the day, making north-facing installations economically unviable.

This comprehensive one-hour tutorial covers fundamental concepts of solar photovoltaic systems including PV tilt and azimuth angles relative to sun altitude, energy units, factors affecting power production, peak sun hours calculation, system sizing methodology, and I-V characteristics of solar panels, enabling learners to understand how solar panels generate electricity and how to calculate their power output.

Photovoltaic panel installation requires careful attention to orientation and inclination to maximize energy production. Two critical parameters determine performance: orientation (angle relative to true south in Northern Hemisphere or true north in Southern Hemisphere) and inclination angle (slope relative to horizon and latitude). Optimal orientation is south-facing in the Northern Hemisphere and north-facing in the Southern Hemisphere. Energy yield decreases proportionally with orientation deviation: South-East and South-West orientations yield approximately 94%, East and West orientations yield approximately 77-81%. The sun rises in the east and sets in the west in both hemispheres, but its apparent path relative to optimal orientation is reversed.

Solar panel efficiency depends critically on orientation and inclination angle. South-facing panels at 25-35° inclination provide maximum efficiency year-round. West-facing panels perform best in summer when the sun sets low, while east-facing panels excel in morning hours. However, both east and west orientations achieve only about 30% of south-facing panel efficiency. During winter, the sun's lower path makes east and west orientations particularly ineffective. Panels mounted at 90° (vertical) have very low efficiency regardless of season. For comprehensive daily energy production, a system should include south, east, and west orientations to capture sunlight throughout the day and across seasons.

Sensors convert physical quantities into electrical signals for microcontroller processing. Transducers include sensors (detecting environmental changes) and actuators (producing physical responses). Common sensors measure temperature, humidity, pressure, and light. Light Dependent Resistors (LDRs) change resistance inversely with light intensity—high resistance in darkness, low resistance in bright light. LDRs connect in voltage divider circuits with fixed resistors, producing variable voltages proportional to light levels. These voltages feed into microcontroller analog inputs for measurement. LDR applications include automatic street lighting, camera light meters, and environmental monitoring systems. Understanding sensor characteristics and output types is essential for proper system integration and signal conditioning.

An LDR (Light Dependent Resistor) sensor works on the principle of photoconductivity, where its electrical resistance decreases as light intensity increases; it consists of a photoconductive material (typically cadmium sulfide) deposited on a ceramic substrate with two contact plates, and is commonly used in light-sensing applications such as automatic street lighting and light meters.

A Light Dependent Resistor (LDR), also known as a photoresistor, is an electronic component whose electrical resistance decreases when exposed to light and increases in darkness. This inverse relationship between light intensity and resistance makes LDRs useful for automatic light-sensing applications such as street lights and flashlights, which can turn on automatically when it gets dark and turn off when it becomes bright.

An LDR is made from semiconductor materials, typically cadmium sulfide, deposited in a special pattern on an insulating base. The working principle is based on the increase in electrical conductivity of the semiconductor when light falls on it. When light photons strike the semiconductor surface, they transfer energy to electrons in the outer orbits, causing them to become free charge carriers. As the number of free electrons increases, the electrical conductivity increases, and consequently, the resistance decreases. This relationship between light intensity and resistance forms the basis for light detection applications.

LDR (Light Dependent Resistor) is a two-pin sensor whose resistance changes with light intensity. In darkness, resistance is high (around 5kΩ); in bright light, resistance decreases (can go to 500Ω or lower). LDRs are used in automatic street light control systems where the sensor detects ambient light levels. The resistance change is fed to a transistor switch, which controls a relay to turn the street light on at sunset and off at sunrise. The sensitivity can be adjusted by changing the fixed resistor value in the voltage divider circuit.

Linear actuators convert DC motor rotation into linear motion using gearboxes and ball screws. They operate on 12-24V DC with two-wire control, where reversing polarity changes direction. Complete control requires three states: extend, retract, and off. Simple on/off switches are insufficient; three-position polarity-reversing rocker switches provide complete manual control by switching between extending, retracting, and open-circuit states through internal common contacts and jumper wires.

An actuator converts electrical energy into mechanical motion, producing either rotational or linear movement. Linear actuators use internal DC motors and worm gears to convert rotation into straight-line motion, with force measured in Newtons (convertible to kilogram-force for intuitive understanding). They feature holding force that maintains position when unpowered. Key specifications include maximum output force and extension range. Linear actuators operate with simple two-wire control (voltage direction determines direction) and require motor drivers due to high current draw. Applications include adjustable furniture where precise height control with indefinite holding capability is essential.

Servo motors are more sophisticated than basic motors, featuring an internal control board and counter that track position through pulse signals (typically 5ms intervals), allowing precise angular control; they can function as simple motors if the control board is removed, while linear actuators use a motor to move a piston in a straight line with mechanical stops for position feedback.

A linear actuator is a mechanical device that converts energy such as power from air, electricity, or liquid to create motion in a straight line and may be used to apply a force. In this lesson, the focus is on how the electrical-mechanical aspects of linear motion control are applied when using stepper or servo motors.

A linear actuator (linear motor) is an electromechanical device that converts electrical energy into linear motion, featuring a motor with gears that drive a piston to extend or retract; it operates by reversing the polarity of the applied voltage (typically 12V) to control direction, with built-in end-of-travel switches for protection, and can be controlled through simple polarity reversal circuits or more advanced microcontroller-based systems with PWM for speed adjustment.