Solar Water Heating System Using Fresnel Lens with 6-DOF Tracking [Patent 10-2023-0027486]

August 30, 2023

Overview

This project demonstrates an integrated solar water-heating prototype that combines a PMMA Fresnel lens with a 6-DOF robotic manipulator for precise solar tracking. The system uses the Solar Position Algorithm (SPA) for coarse alignment and a novel low-cost sun-angle sensor for fine adjustments.

Key Features

• 6-DOF Robotic Arm: Enables precise orientation and translation for optimal focus.
• Fresnel Lens Concentrator: Lightweight, cost-effective optical concentration.
• Low-Cost Sun Sensor: 4×4 LDR array with polarizer shroud and calibration logic.
• Thermal Feedback: Safety mechanism to prevent overheating.
• Energy Autonomy: Powered by a 40 Wp solar panel with Li-ion storage.

System Architecture

The control pipeline integrates SPA-based solar position calculation, inverse kinematics for the robotic arm, and fine steering using the sun sensor. Temperature feedback ensures safe operation.

Hardware Setup

The hardware setup includes the Fresnel lens mounted on the robotic arm, a compact heat exchanger at the focal point, and an embedded controller (Raspberry Pi + Arduino).

Novel Sun Sensor Design

The sun sensor uses a 4×4 LDR array with a polarizer shroud and ultra-black coating to minimize glare. Calibration equalizes sensor response, and a threshold-based algorithm estimates tilt direction.

Results

Thermal Safety

A temperature feedback loop monitors the receiver and triggers defocus/reset when thresholds are exceeded, ensuring safe operation in construction environments.

Applications in Construction

This system is ideal for temporary hot-water supply on construction sites, off-grid commissioning, and façade testing. Its modular design and low-cost sensor make it practical for field deployment.