Introduction Low electrification rates worldwide Expensive or
dangerous means of energy In the US, natural disasters cause people
to lose power for extended amounts of time.
Slide 3
Solar Power Solar power generation is ideal for these
situations. It is virtually harmless to the environment and
inexpensive with greatest cost from battery replacement. PV modules
convert solar radiation into DC electricity.
Slide 4
Overview of System
Slide 5
Engineering Requirements Performance The PV array will include
a solar tracker which will track the Sun with a maximum error of
15. The PV array will have module efficiency greater than 13%.
Economic The cost for the entire system (parts and labor) should
not exceed $2,500. Energy The system should be able to supply a
load demand of at least 500 Watt-hours per day. Maintainability The
system should have a robust design such that failed components can
be replaced easily by a technician. Operational The system should
be able to operate in a temperature range of 0 to 75C. The PV array
will be positioned such that it is not shaded by trees, buildings,
or other physical objects at any time. Availability The PV array
will output dc power from sunrise to sunset, 365 days a year,
except during unsuitable conditions (cloud cover, inclement
weather, e.g.)
Slide 6
Grape Solar 100W Solar Panel $189.99 from Costco 36 cell
Monocrystalline 18.5 Vmpp, 5.42 Impp 47.0 tall x 21.1 wide x 1.57
thick 17.6 lbs Approximately 19% efficiency Average daily
production Run a 60W light bulb for 4 hours Power a laptop for 5
hours Operate a 25 TV for 2 hours through an inverter Fully charge
over 30 cell phone batteries.
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2-Axis Tracking The percentage of incident solar energy the
panel can convert into electrical energy depends on the amount of
energy in the solar radiation but also the angle between the
radiation and the module. 2-axis tracking keeps that angle at 90
degrees, maximizing conversion efficiency. 34% increase in energy
absorption, as opposed to no tracking.
Slide 8
Solar Tracking Began with LED based tracking using photodiodes
Implementation of Arduino to increase accuracy Replaced photodiodes
with solar cells to increase output power
Slide 9
PCB Schematics Voltage Regulator Solar Tracker
Slide 10
The Solar Tracker Analog Design Recap Project advancements -
Arduino Usage - Servos/Recalibration - Power Consumption
Programming - Ideal - Non-Ideal
Slide 11
Analog Design Recap Comparator Compares Solar Cell to Vref Vref
makes tracking accurate Outputs to Logic Circuit TTL Logic
Issue
Slide 12
Analog Design Recap Uses output from comparator Gives proper
input to H- Bridge H-Bridge Drives the motor CommandR1R2R3R4Sensor
LSensor R Stop/Coast010100 Clockwise001110 C-Clockwise110001
Brake111111
Slide 13
Analog Design Recap Found about 35-40 Degrees was best Test
done indoors and outdoors Tests proved little recalibration was
needed Fixed Swivel Issue
Slide 14
Analog Design Recap Added multi-turn pot to increase accuracy
Arduino doesnt need adjusting Current approx. Vref Inside Vref2.9v
Inside Solar Cell3.5v Outside Vref6.25v Outside Solar
Cell~6.80v
Slide 15
Project advancements Replaced analog circuitry (LC/H-Bridge)
Allows programming of non-idea conditions Can power prototype
servos Takes input from analog comparators, then controls servos
based on the analog input
Slide 16
Project Advancements
Slide 17
Servo Positioning Gearbox coupled to the shaft Used to directly
move the solar panel for Azimuth and Altitude No weight put on the
servo itself Loosening the coupler allows calibration of
servos
Slide 18
Recalibration of Servos Calibrated servos to 0 th degree Issue
with Altitude coupling Resolved issue by recalibrating Adjusted ~20
Degrees
Slide 19
Integrating the Solar Tracker Similar to the prototype but
larger Still using the same circuitry Tracker added to side of
system Adjusted Vref for sunlight
Slide 20
Servo Power Consumption Power less than expected HS-805BB Servo
consumes.2 -.5A Servo specification show.8A or higher Possible to
reach 1A under certain weather conditions
Slide 21
Programming: Ideal
Slide 22
Slide 23
Slide 24
Programming: Non-Ideal
Slide 25
Slide 26
System Testing
Slide 27
Charge Controller Protect Battery Life Preventing Overvoltage
Preventing Overcurrent Displays Status Voltage State of Charge
Slide 28
Charge Controller
Slide 29
Components Solid State Relay 4 port operation Driven with low
voltage input 10.67 V
Slide 30
Components Voltage Regulator With heatsink to withstand 8 A
13.75 = 1.25 * (1 + R2/R1)
Slide 31
Components Current Sensor Hall Effect Sensor Current flows
through terminals Output to Arduino analog pin 133 mV/A
Slide 32
Components Voltage Divider
Slide 33
Total System Overview
Slide 34
Panel Testing Elevation Angle (in degrees up from horizon)
Voltage (in Volts DC) 020.7 9020.2 4520.2 5820.4 Elevation = 0
Elevation = 45 Elevation = 90 Elevation = 58
Slide 35
The Battery Discover EV Traction Dry Cell: EV24A-A 12 V 85 AH
Dry Cell battery has virtually identical performance
characteristics to SLAs. $200
Slide 36
Inverter Cobra CPI880 800 W Two AC receptacles and a USB outlet
Will Power Arduino/Charge Controller Motors Output power Inverter
shown connected to battery
Slide 37
Battery Capability 20 HR rating = 85 Amp Hours Can power a
constant 4.25 Amp load for 20 hours Wattage levels much higher when
connected to panel Graph shows battery data for the battery
isolated from the charging system
