P14421: Smart PV PanelBobby Jones: Team LeaderSean KitkoAlicia OswaldDanielle HoweChris Torbitt

AGENDA

•Background•Heat Analysis•Power Electronics•Controller•Sensors•Ink Research•BOM•Schedule

BACKGROUND

•Advance Power Systems▫Jasper Ball▫Atlanta, GA

•Snow reduces power output of PV panels•Develop method to prevent snow from

accumulating in the first place▫Apply current to conductive, heating ink▫Keep temperature of panel surface above

freezing▫Sense presence of snow

PROJECT BACKGROUND

Needs List

Engineering Requirements

PROOF OF CONCEPT

POC ENERGY USAGE ANALYSIS

Final finding to melt one year worth of snow: 48,502,500J

E msh (mCpT)g (mCpT)sVariables

Name   Units ValueCps specific heat capacity of snow j/(kg*K) 2090Cpg specific heat of tempered glass j/(kg*K) 720h heat fusion of snow* J/kg 334000ρs average density of new snow kg/m^3 60 average snowfall annually rocherster m 2.344

ρg average density of tempered glass kg/m^3 2440

T (°C)Tig -5Tfg 5Tis -5Tfs 0

*For snow, use the parameter of ice

Need to determine total energy needed to heat panel and melt snow over the period of a year:

POC POWER REQUIRMENT

•The Data:▫TMY3 (Typical Meteorological Year)▫Hourly data taken from 1961-1990 and

1991-2005▫Takes the month that is closest to the

average

•Calculations make use of the direct and the diffuse beams from sunlight in Rochester, NY taken from this data

POC POWER REQUIRMENT con’t•Assumptions:

▫Latitude: 43.12° (Rochester, NY)▫Local Longitude: 77.63°▫Local Time Meridian: 75°▫PV efficiency of 20%▫A directly facing south panel▫Use tilt angles 10°-35° in steps of 5°▫Reflected off grass in summer (ρ=0.2)▫Reflected off snow in winter (ρ=0.8)

POC POWER REQUIRMENT con’t•Equations:

▫Convert civil time to solar time

▫Calculate Solar Declination Angle

POC POWER REQUIRMENT con’t

• Calculate Solar Altitude Angle

• Calculate Solar Azimuth Angle

POC POWER REQUIRMENT con’t

• Calculate Direct Beam on the panel:

• Calculate Diffuse

• Calculate Reflected

POC POWER REQUIRMENT con’t•Calculation done for every hour of the

day. •Then added together to get the amount of

solar flux available in a given year at different tilt angles. These fluxes were averaged giving: 291,113 Wh/m2

• Restricted to 10% of annual power: 29,111 Wh/m2

Energy Conclusion

•Yes! 48,502,500J<104,800,822•Next steps:

▫Model in ANSYS Model different ink layouts for feasibility

Power Electronics

•Battery•Charging System•Supplying Power to Ink

Choosing the Battery•Battery Type has to first be chosen

“Batteries and Charge Control for Stand-Alone Photovoltaic Systems : Fundamentals and Applications” , James P. Dunlop

Battery Capacity• How much energy is stored in the battery measured in

ampere hours

• Ah will provide ‘X’ amps of current for ‘Y’ hrs

• From previous calculation we assume the total amount of power that we can use is 29,000 Wh/m2 , are prototype is 3’x5’ (0.92m x 1.525m)

• Therefore the total power used in a year can be about 40,600Wh

Battery Capacity

• Assuming snowfall for 240hrs a year the average amount of power of the device will be 170W (40,600Wh/240h)

• Therefore Ah = (170W*4h)/ 12V = 56Ah

• To increase battery performance and life the battery should not be consistently discharged below 60% capacity so to be safe the battery capacity should be about 90Ah

(V) Voltageattery

(Hrs) TimeRun * (W) WattageDevice

BAh

Battery Options•Trojan Deep-Cycle AGM Battery can be used•31-AGM could all be options with 5hr rate-

capacity of 82Ah•Can be purchased from civicsolar for $270

Battery Chargers

•Controls incoming charge of the battery•AGM batteries are INTOLERANT to

overcharge•Standard Solar Chargers or MPPT

(Maximum power point tracking) charger•MPPT chargers are much more efficient•Standard chargers can lose between 20-

60% of the rated solar panel wattage

Choosing a Battery Charger• Charger needs to be able to handle rated watt, voltage,

and current rating of PV panel (charging source)• Charging source is still being determined (Full Panel or

select number of cells)• For now we can base the charger choice off a SBM

solar 150W panel with the following specs:

Possible MPPT Charge Controller• Morningstar SunSaver 15 Amp MPPT Solar

Charge Controller ($225)

Power used from possible 150W:Power= PV Panel Power * EfficiencyPower = 150W * 97.5%Power=146.25

Charge Current = Power/Battery VoltageCharge Current = 146.25W/12VCharge Current =12.2A

Charging Time = Battery Ah / Charge Current

= 100Ah/ (12.2A)Charging Time = 8.2 hrs

Possible Standard Charge Controller• Morningstar SS-20L 20 Amp PWM Solar Charge

Controllers w/LVD ($78)

Power used from possible 150W:Power = Voltage *Charge

CurrentPower = 12V *8APower = 96W about 66%

efficient

Charging Time = Battery Ah / Charge Current

= 100Ah/ (8A)Charging Time = 12.5 hrs

Battery

Regulating Circuit

Rtrace1

Rtrace2

Rtrace3

Rtrace4

Ink Power Supply

RTotal

I out

TotalR

PowerI

Ink)Heat toNeeded (out

POC CONTROL SYSTEM

• Atmel's ATMega328P 8-Bit Processor in 28 pin DIP package with in system programmable flash

Features:•32K of program space•23 programmable I/O lines 6 of which are channels for the 10-bit ADC. •Runs up to 20MHz with external crystal. •Package can be programmed in circuit. •1.8V to 5V operating voltage•External and Internal Interrupt Sources•Temperature Range: -40C to 85C•Power Consumption at 1MHz, 1.8V, 25C

–Active Mode: 0.2mA–Power-down Mode: 0.1μA–Power-save Mode: 0.75μA (Including 32kHz RTC)

POC CONTROL SYSTEM Con’t

POC CONTROL SYSTEM Con’tControl System Pseudocode

• Reset• Enable global interrupts on interrupt input pins 4 and 5• Define interrupt on pin 4 or 5 for a rising edge signal from

sensor conditioning logic for inputs from temperature/proximity/moisture etc sensors

• Enter Sleep Mode• Rising edge?

Yes: o Go to ISR (Interrupt Service Routine) if rising edge is triggeredo Run specified program based on polled sensor values

No: o Continue to sleep

POC SENSOR RESEARCH Snow will be sensed by monitoring 5 sensors

Ambient temperature Panel temperature Precipitation Ambient light Motion/Proximity

Use of all 5 sensors would allow for sufficient redundancy to ensure proper operation.

POC SENSOR RESEARCH con’tAmbient temperature

Will be used in combination with panel temperature

If ambient temperature >~5◦C, then operation should not be necessary.

Achieved with basic temperature sensor:

Analog Devices TMP36

POC SENSOR RESEARCH con’tPanel temperature

Will be used in combination with ambient temperature

If ambient temperature >~1◦C, then operation should not be necessary.

Achieved with basic thermocouple/thermistor:

Omega 5LRTC series, type T thermocouple

Spectrum Sensors & Controls RT24 Surface Temperature Sensor

POC SENSOR RESEARCH con’tPrecipitation

Most difficult/most expensive to implement

Operates by applying a small amount of power to a small heater, and then looking for water

Automatically operates only at specific temperature range.

ETI CIT-1 Snow Sensor

POC SENSOR RESEARCH con’tAmbient light

Small photocell Will allow for optimized

operation (operation will shut down after an extended period in low-light environment).

Intersil ISL29101

POC SENSOR RESEARCH con’tMotion/Proximity

Transmissive infrared or ultrasonic sensor

Will provide some estimation of how much/fast it is snowing (allowing for operation optimization)

Omron E4E2 Ultrasonic Sensor

Chamberlain IR 801CB garage door safety sensors (or something similar).

POC INK RESEARCH•Brinkman Lab Testing 10/24/2013

▫The point of the test was to obtain the appropriate parameters to use on the pulseforge for the curing process.

▫Tested a copper based ink usually used on paper

▫Wanted to see how the ink would be effected by putting it on glass

POC INK RESEARCH con’t▫Setup:

Ink was placed at the top of a screen with the glass below.

POC INK RESEARCH con’t Ink was then spread across the screen with

two passes. The screen gave the following pattern on the glass

POC INK RESEARCH con’t The pattern was then covered with paper so

only two lines on a trace were exposed. This was done so different parameters could be tested for the pulseforge two lines at a time.

POC INK RESEARCH con’t Eight trials were done at different parameters. (1

to 8 right to left) Conclusion: This copper based ink is coming off

the glass Next Step: Find a different ink that is adhesive to

glass

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BILL OF MATERIALS

TEST PLAN OUTLINE• Test Ink

▫Verify heat dispersion, and ink durability• Test Control System

▫Verify appropriate output signal and system response

• Test Battery▫Verify battery life/performance and response to cold

• Test Power/Charging Electronics▫Verify power output and charging capabilities

• Test Sensors▫Test different sensing options

• System Integration Test▫Verify all subsystems operate together

SCHEDULE