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SOUTH AFRICA POWER GENERATION GROUP MEMBERS Genesh Chen-Shue EE Steven Bularca CS & CpE Aldo Puente EE & CpE Armel Nidjeu EE MOTIVATION • Great need of electricity in the small South African community of the Pomolong Township, which is occupied by the less fortunate people of South Africa due to the aftereffects of apartheid. • They are cut off from the rest of the world because they do not have electricity that will enable them to use electronic devices such computers, cell phones, and TVs. • Even if they could afford the cost of power, the township is not close to the power grid. GOALS AND OBJECTIVES • • • • • • • • Some of the sources that were considered were wind, hydro, solar, and mechanical/kinetic energy. The absolute most important objective is safety, because ensuring that the system is safe protects lives and mitigates damages. A major objective of this project is for the power generating system to be extremely efficient, because the resources are scarce and utilizing every bit of energy gives the townspeople more time to enjoy the electricity. Keeping in mind the technology aptitude of the users, ease of use became an unavoidable objective. One of the objectives is to successfully capture as much sunlight energy as possible. This will be done through a MPPT charge controller system. Deep cycle batteries are what are planned to be implemented for the project, because deep cycle batteries are made to be completely drained. The inverter will take the power from the charged batteries in the form of a DC input. desired. A robust, weather resistant, and safe enclosure to keep the entire system secure is a crucial part of the project. PROJECT SPECIFICATIONS Spec. # Specification 1 Ability to capture 6 hour of solar energy by our 500 W solar panel system. Solar panels will be two 300 W solar panel each which will be mounted on the roof of the community center of township. 2 Must be able to power up to 500 W electronics for a period of 4 hours daily. 3 Must be robust, weatherproof, safe, long lasting, and easy to maintain. 4 There must be a gauge to measure battery charge. 5 Inverter must able to support an input of 12V and output 220V at ~50 Hz 6 Batteries must last at least 4 years. They will be placed in parallel making a 12V unit. Each battery will be 12V. 7 Charge controller must implement MPPT for the solar energy capture. BLOCK DIAGRAM ENERGY • • We chose to use renewable energy over fossil or nuclear energy because the latter resources were not obtainable The renewable energy we chose to use was solar because it was scalable and could produce the most power given the limitation of funding. • Power for solar panels cost around 1-2 dollars per Watt. For example, 2 305W Helios PV panels cost $752, making the cost per watt for that particular panel $1.23 per Watt. • South Africa Irradiation levels are high • The other renewable energy source that was considered was wind, but based on research, the cost for a wind turbine that would generate enough power was out of our budget range TYPES OF SOLAR PANELS Semiconductor Material Power Conversion Efficiency [%] Technology Mono-crystalline silicon 20-24 Crystalline Poly-crystalline silicon 13-18 Thick and Thin-film Gallium-arsenide Amorphous silicon 20-29 8-13 Crystalline Thin-film Cadmium telluride 10-17 Thin-film Cadmium indium selenide 10-19 Thin-film MONOCRYSTALLINE PANEL CHOSEN Brand Model Watts Cost Height Length Cost PP Cost PW Helios 6T-250 250 $697.65 1,680 mm 990 mm $348.25 $1.39 ReneSola Virtus 250 $431.92 1,640 mm 992 mm $215.96 $0.86 Suniva OPT250-60-4-1B0 250 $775.75 1,653 mm 982 mm $387.88 $1.16 CHOSEN SOLAR PANEL AND FRAME CHARGE CONTROLLER CHARGE CONTROLLER – CONSIDERED CIRCUITS 555 Timer TIBQ24650 TISM72442 NXP MPT612 Input Volt. Range 2-15 V 5-28 V 4.75-5.25 V 1.8 V Max. Operating Temp. 70 C 125 C 105 C 150 C Price $0.75 $5.18 $8.89 $7.98 SOLAR PANEL VOLTAGE SENSOR CIRCUIT SOLAR PANEL CURRENT SENSOR CIRCUIT MPT612 BUCK-BOOST CONVERTER POWER SUPPLY JTAG/UART ADD ON BOARD THE DC/AC INVERTER INVERTER CONSIDERED CIRCUITS 555 Timer MSP430F2013QRSATEP Input Volt. Range 2-15 V 1.8-3.6 Max. Operating Temp. 70 C 125C Price $0.75 $2.93 SIGNAL GENERATION H-BRIDGE P-Channel • P-channel devices have a higher ‘on’ resistance so there is greater power loss N-Channel • N-channel device will require a driver with a bootstrap capacitor to generate the higher voltage above the switching voltage of 230V to turn on the device We decided to use IRFP260N-Channel MOSFETs, because efficiency was a stronger factor than convenience. OUTPUT FILTER • System is filtered by an RC Low Pass Filter with: A 200V 1800uf electrolytic capacitor A Metalized Polypropylene Film Capacitor. INVERTER OUTPUT INVERTER PCB We used Eagle for the PCB Design and Ordered the PCB from Hackvana.com TYPES OF DEEP CYCLE BATTERIES Flooded Gel AGM Model HRL12280WFR UB-24 UB-GC2, 6V 225 Ah Cost $240 $325 $232 Performance Safety 88% charge/discharge efficiency Hazardous 90% charge/discharge efficiency Hazardous 98% charge/discharge efficiency Non-hazardous Size 6V, 12V,24V 6V, 12V, 24V 6V, 12V, 24V Availability Easy to find Internationally Add water Hard to Find Internationally No Maintenance needed Hard to Find Internationally No Maintenance needed Maintenance BATTERY CONSIDERATIONS We had to calculate the amount of charge capacity the batteries should hold so we use Peukert’s Law: t=H(C/IH)^k Peukert's Law expresses the capacity of a battery in terms of discharge rate, where t is the total time to discharge the battery, k is the Peukert constant, I is the discharge current, C is the rated capacity at the discharge rate, and H is the rated discharge time. We Calculated the proper Ah parameter to be around 75Ah. Considering the different battery types, we decided on flooded batteries because of the vast amounts available in the world. If the batteries needed to be replaced, we wanted the option that is the easiest to replace while maintaining a low cost. BATTERIES ENCASING CABLE WIRE USE 2 WIRE RHH or RHW Used for grounded system Rated at 600 v Maximum operating temperature is 90C Conductor: copper, aluminum, copper glad- aluminum Stranded or solid conductor Price .50/ft PV wire UL 4703 Used for both undergrounded and grounded system Rated at up to 2000 v Maximum operating temperature150C Conductor: copper Stranded copper or tinned copper .58/ft LOAD WORK DISTRIBUTION Name Charge Controller Solar Panels Inverter Batteries Other Steven XXXXXX X XX X XX Genesh XX XXXX XXX X XXX Aldo XX X XXXXX X XXX Armel X XX XXX XXXX XX BUDGET Part Vendor Quantity Price ($) 250 Watt Solar Panel 72 Mono Crystalline Cells 36 Volt 76T250 Helios 2 700.00 12V 75Ah 280W Batteries CSB 3 400.00 Charge Controller based on MPT612 N/A (Designed) 1 300.00 Modified Sine Wave Inverter N/A (Designed) 1 100.00 Chassis and Weatherproofing N/A (Designed) 1 200.00 Miscellaneous Electronic Components and Wires N/A N/A 295.00 Total 1995.00 ISSUES • Charge Controller • Finding an Inductor that can handle the current • Buck-Boost converter • Inverter • Boost Converter • Isolation of power lines from control line • Other Issues • Ventilation of Batteries • Sponsors Questions?