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
POC ENERGY USAGE ANALYSIS Final finding to melt one year worth of snow: 48,502,500J Variables Name UnitsValue C ps specific heat capacity of snowj/(kg*K)2090 C pg specific heat of tempered glassj/(kg*K)720 hheat fusion of snow*J/kg334000 ρsρs average density of new snowkg/m^360 average snowfall annually rochersterm2.344 ρgρg average density of tempered glasskg/m^32440 T (°C) T ig -5 T fg 5 T is -5 Tf s 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 cont 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 cont Equations: Convert civil time to solar time Calculate Solar Declination Angle
POC POWER REQUIRMENT cont Calculate Solar Altitude Angle Calculate Solar Azimuth Angle
POC POWER REQUIRMENT cont Calculate Direct Beam on the panel: Calculate Diffuse Calculate Reflected
POC POWER REQUIRMENT cont 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/m 2 Restricted to 10% of annual power: 29,111 Wh/m 2
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/m 2, are prototype is 3x5 (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
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 * Efficiency Power = 150W * 97.5% Power=146.25 Charge Current = Power/Battery Voltage Charge Current = 146.25W/12V Charge 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 Current Power = 12V *8A Power = 96W about 66% efficient Charging Time = Battery Ah / Charge Current = 100Ah/ (8A) Charging Time = 12.5 hrs
Battery Regulating Circuit R trace1 R trace2 R trace3 R trace4 Ink Power Supply R Total I 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, 25 C –Active Mode: 0.2mA –Power-down Mode: 0.1μA –Power-save Mode: 0.75μA (Including 32kHz RTC)
Control 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 triggered o 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 cont Ambient 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 cont Panel 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 cont Precipitation 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 cont Ambient 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 cont Motion/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 cont Setup: Ink was placed at the top of a screen with the glass below.
POC INK RESEARCH cont Ink was then spread across the screen with two passes. The screen gave the following pattern on the glass
POC INK RESEARCH cont 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 cont 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 12 34 567 8
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
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