Peltier Solar Concentrator

By: Michael ForrestKyle FifieldEvan White

The Problem

• To demonstrate that a thermoelectric device can efficiently converted solar energy into electricity.

• The goal is to create a system at least as efficient as PV panels.

The Solution

• Satellite Dish Solar Concentrator• Hi-Z HZ-20 Thermoelectric Module• Aluminum Collector Plate• Time-Based Solar Coordinate Tracking• Battery Storage• LCD User Interface

What is a Thermoelectric Device?

• In a thermoelectric device, a voltage is created when a difference in temperature exists across the device.

• By heating one side of the device and sinking heat from the other side, an electric voltage will be created.

Solar Rays

Solar Concentrator

Sun

Thermoelectric Device

Collector Plate

Azimuth Rotation

Horizontal Tilt

Dc/Dc Step-up

Microcontroller

Motor Controller Motor Controller

System Diagram

Solar Tracking Subsystem

• Real-Time Clock (DS1307)• User interface with Buttons and LCD Screen• Microcontroller (Coldfire)• Motor Controller (H-Bridge)• DC Motor with Potentiometer (Azimuth) • Linear Actuator with Accelerometer (Altitude)

Solar Tracking System Diagram

H-Bridge Circuit

Coldfire Microcontroller

Time of Day Sensor

Potentiometer

Accelerometer

LCD Display and User Interface H-Bridge

Circuit

Motor

Linear Actuator

Solar Tracking Positioning EquationsAltitude Angle =

Azimuth Angle =

Inputs• Date and Time• Longitude and Latitude

scos

Microcontroller Code

Solar Rays

Solar Concentrator

Sun

Thermoelectric Device

Collector Plate

Azimuth Rotation

Horizontal Tilt

Microcontroller

Motor Controller Motor Controller

System Diagram

Mechanical Azimuth Tracking

Elevation Tracking

Linear Actuator

Solar Concentrator

Highest Sun Elevation (70⁰) Lowest Sun Elevation (12⁰)

70⁰ 12⁰

6 inch Stroke

Tracking Code

Thermoelectric Collector Plate Mount

• Purpose:– Maximize Performance and Power Efficiency of HZ-20.– HZ-20 Module Around 5% Efficient.

• Design Aspects:– Minimum Load of 200 psi on HZ-20.– Thermal Expansion of HZ-20.– Efficient Heat Transfer– Keeping Cold Side of HZ-20 Cool.

Subsystem Diagram of Thermoelectric Mount

Collector PlateThermoelectric Device

Heat Sink

Belleville Springs

Solar Rays

Hot Side

Cool Side

Loading on HZ-20 Module

• Ensures Module Remains in Compression to Maximize Heat Transfer.

• Solution:– Belleville Springs.– Apply Large Amount of

Force in Compact Area.– Also Allows for Thermal

Expansion.

Load and Thermal Expansion CalculationsThermoelectric Device Dimensions

Load Required: 200 psi*

Where: = Change in Length = Thermal Expansion*= Change in Temp.= Initial length

Force Calculation

Thermal Expansion Calculation

*Information Given from Specification Sheets

Efficient Heat Transfer

• Thermal Grease:– Ensures Efficient Heat Transfer from Mount to HZ-20 and

HZ-20 to Heat Sink.

• Overhang of 0.5 Inches and 0.25 Inches of Thickness on Mount:– Ensures Uniform Heating on HZ-20.

Thermal Resistance DiagramTBar

TH

TC

THS

TA

∆TThermal Resistance

of Thermal Adhesive

Thermal Resistance of Thermoelectric Junction

Thermal Resistance of

Heat Sink

Temperature of Bar

Temperature of Hot Side

Temperature of Cold Side

Temperature of Heat Sink

Temperature of Ambient

Energy Gain

B

A AreaEclipes = πAB

Area of Dish = 0.303077m²

Area of FP = 0.003488m²

Energy Gain = Area of Dish / Area of Focal Point

Energy Gain = 87

Efficiency Strategies

85% Reflectivity Dish Covered with Reflective Tape

Aluminum Collector Plate Painted Black

Absorbs 90% of light

Efficiency Diagram

Reflective Tape 85% Efficient

Sun

90% Absorption Efficiency

5% Heat to Electricity Efficiency

Wasted Heat

Step-up Dc/Dc Converter

95% Efficient 12v Lead Acid

92% Storage Efficiency

Total Efficiency = 3.34%

Sunlight to Usable Energy

Power Diagram

1000W/m²

303.1W

Sun

Concentrator Collector

232W

8 mins to heat up

Thermoelectric Device

220W

Heat Sink

3V, 6.67A, 20W

Dc/Dc Step-up

12V, 1.6A, 19W

Dc/Dc Step-up Convertor

1.8V to 5.5V

User InterfaceDisplays:• Time of Day• Date• Azimuth Angle• Altitude Angle

Pushbuttons:• Up/Down

Selection Arrows• Menu Option• Enter Button

Areas of Responsibility

Evan

Kyle

Mike

Solid Modeling / Thermoelectric Device Mounting / Altitude Tracking Mechanical

Energy & Power Calculations/ Thermal Design/ Dc-Dc Step-Up Circuit/ Azimuth Tracking Mechanical / Base Design

Solar Tracking Programming/ Real Time Clock Programming/ Angle Calculations/ LCD User Interface Programming and Design

Project Management

BudgetItem Part Number Store Length/Package Quanity Order Quanity Price

Cold Draw 1" x 1.5" x 12" 8910K838 McMaster Carr 12" 1 $24.28 Steel Hex Head Cap Screw 3/4"-10 Thread 3 - 1/2" Length 91247A849 McMaster Carr 5 1 $10.45 Hex Nut 3/4"-10 Thread 1-1/4"W, 27/64"H 91015A036 McMaster Carr 5 1 $5.17 Plain Steel Type A SAE Flat Washer 3/4" Screw Size 91083A036 McMaster Carr 21 1 $3.00 Steel Flange-Mounted Ball Bearings 7208K51 McMaster Carr 1 1 $23.34 Setscrew Shaft Collars 3/8" Bore 9414T8 McMaster Carr 1 2 $0.72 Black-Oxide Coated Steel Shaft 3/8" OD 1886K12 McMaster Carr 18" 1 $11.40 Steel Timing Belt Pulley Pitch Diameter 0.637", 0.2 Pitch 6495K711 McMaster Carr 1 1 $10.54 Steel Timing Belt Pulley Pitch Diameter 3.80", 0.2 Pitch 6495K732 McMaster Carr 1 1 $38.85 Timing Belt 0.2 Pitch, 27.0" Outer Circle 1679K143 McMaster Carr 1 1 $9.82 Compact DC Gearmotor 12 VDC, 0.6 rpm 6409K11 McMaster Carr 1 1 $44.96 Setscrew Shaft Collars 3/16" Bore 9414T5 McMaster Carr 1 1 $0.62 Aluminum Metric T-Slotted Mounting Bracket, 40mm 5537T244 McMaster Carr 1 2 $13.46 Set-Screw Shaft Coupling 5/16" Bore 2424K12 McMaster Carr 1 1 $7.63 Nylon Flat Belt Idler Pulley 3/8" Bore 6235K64 McMaster Carr 1 1 $12.48 5/16" Drive Shaft 1327K72 McMaster Carr 6" 1 $6.50

TOTAL $237.40

Questions?