Sun tracking schemes for photovoltaic panels

Sun Tracking Schemes for

Photovoltaic Panels

Marzia Hoque TaniaMd. Samiul Alam

Objective

Design & implementation of Single axis trackerDesign & implementation of Dual axis trackerPerformance synopsis

Aspects of Sun Position

Source:Electropaedia

Aspects of Sun Position: Continue

Authors’ permission required

A Solar tracker is a device for orienting a solar photovoltaic panel or concentrating solar reflector or lens toward the sun. The sun's position in the sky varies both with the seasons (elevation) and time of day as the sun moves across the sky.

A Solar Tracker

Solar TrackersConsidering movement capability- Fixed surfaces One axis trackers Two axes trackers

Regarding control units- Passive Microprocessor and Electro-optical

Picture: Market Electrification Systems at Barkal Upazila under Rangamati District

Accuracy Requirement

Design & Implementation of the Systems

Block Diagram of Automatic Single Axis Solar Tracking Scheme

System Implementation Flowchart of the Single Axis Tracker

LegendLDR1=Light Dependent Resistor at The EastLDR2=Light Dependent Resistor at The West Forward Rotation=East to WestReverse Rotation=West to East

Start

Input LDR1 & LDR2

LDR1<LDR2?

Rotate required step(East to West)

Get First InterruptStop Forward Rotation

Reverse to Initial Stage

Get Second Interrupt

Stop Processing Until Getting The Input

Activate The Load

Get Input?

End

Yes

No

Yes

No

Time Delay

Methodology and Operation of Designed Single Axis Tracker

Block Diagram of Automatic Dual Axis Solar Tracking Scheme

START

Take Input from the 4 sensors

Compare corresponding Inputs

MovementRequired?

Motor-1,Motor-2or both?

Check movement combination for both

Give proper combination of pulse for motors one

Forward or Reverse?

Forward or Reverse?

Give 1 Pulse Reverse

Give 1 Pulse Forward

Give 1 Pulse Reverse

Give 1 Pulse Forward

Motor 2Motor 1

Yes

No

Both

ForwardReverseForwardReverse

System Implementation Flowchart of the Dual Axis Tracker

Response time: 1 sec

High precisionHigh accuracy

Availability of componentsHigh convergence speed Independence of PV characteristicsNo need of statistical data over a long periodGained power is almost constant over a period

of time

System Verification

Assessment of the Prototype: Single Axis Tracker

No dead band foundDynamic response Least steady state error Energy output increment ~ 21%System can be operated with low maintenanceLow power requirement for circuits operation

Assessment of the Prototype: Dual Axis Tracker

Complex in hardware mechanism Energy increment: 33.5% (theoretical 42%) System power consumption is high System maintenance is excessive Less reliable in bad weather

ConclusionThough the single axis tracker presented here shows high precision and high accuracy to track the sun and the dual axis tracker shows convincing energy gain, these two trackers need to be upgraded to improve- Mechanical System The sensors array The power supply Microprocessor functionality This design can be replicated to larger scale