A Solar Power System for a Residential Application Osman N. Muneer ECET 490 Final Presentation Due: 12/18/08 Instructor: Paul I-Hai Lin, P.E. (EE) Faculty Advisor: Iskandar Hack, P.E. (EE) 1 Introduction What is a solar power system? A solar power system is a system that converts energy from the sun into usable electricity. Sun provides energy for: Solar air heaters o used in conjunction with existing heating system Solar pool heater and spa heater o heats pool or spa Solar water heater o heats water with sun s energy 2
Solar power system composed of: Solar panel Introduction Solar charge controller (regulator) o low voltage disconnect o senses battery voltage is low and turns off all the loads connected to it Temperature sensor o provides protection for the battery by changing control set points 12 V lead acid battery o battery bank capacity at 80% or better Inverter (DC to AC) 3 Function of a Charge Controller The primary objective of a charge controller is to prevent the battery from overcharging and to block any reverse current flow. How does it do that? Regulates voltage and current coming from your solar panel to the battery. Built in circuit with diode which prevents reverse current flow. 4
System Components Fig. 1 (Block diagram of solar panel system) [1] 5 Statement of the Problem I want to make a solar power system where a device could be added so that the solar charge controller can receive a signal to stop getting voltage and current from the solar panel and stop sending voltage and current to the battery because it is fully charged. The device is a battery temperature sensor. 6
Market Analysis Maximum Power Point Tracking solar charge controller (MPPT) most efficient in today s market more features more expensive than PWM (Pulse Width Modulator) MPPT is better investment for long haul Total cost is $584.22 7 Fig. 2 (Outback Power FLEXmax 80 MPPT Solar Charge Controller) [2] Requirements Calculate your AC and DC loads o determine your weekly watt-hours per week o size of the panel depends on how much power is required by your appliances o must know how much energy your battery can store Inverter Selection o Selection based upon your load calculation Solar Array Sizing o figure out average sun hours per day in your area o go to Solar Energy Maps page or check local whether data Battery Size o 12 V cannot be carried efficiently through long cable to battery o If distance between panel and 12 V battery is greater than 75 feet, than use 24 V battery 8
Specifications Solar Panel System Solar Panel Solar Charge Controller Battery Temperature Sensor 12 V Lead Acid Battery DC to AC Inverter Requirements satisfied by solar power system components Absorbs energy and converts it to usable power. Protects battery from overcharging and is a voltage and current regulator. Sends signal to charge controller indicating battery temperature. Provides power to the load and stores excess energy. AC is required for home appliances and television. Table 1: Component Specifications 9 Implementation Shunt transistor Fig. 3 (circuitry of solar charge controller) [3] 10
Solar Panel Methods & Solutions o calculate how much energy it can generate over a period of time. 1) Multiply the panel wattage by the number of hours exposed to sunshine. 2) Multiply the result by 0.85 (factors allows for natural system losses). Example: For the 50 W solar panel in 4 hours of sunshine, 50 X 4 X 0.85 = 170 Wh is generated in 1 hour This is the amount of energy that the solar panel can supply to the battery. 11 Methods & Solutions 12 V lead acid battery o calculate how much energy you can store in battery. 1)convert battery amp-hours into watt-hours by multiplying amp-hours by the battery voltage. Example: For a 50Ah, 12 V battery this is: 50 X 12 = 600 Wh This means the battery could supply a 60 W light for 10 hours. 12
Methods & Solutions Load use over a period of time o calculate how much energy our appliances use over a period of time. 1)Multiply the power consumption by the hours of use. Example: A 13 W fluorescent is on for 5 hours, so it will take 13 X 5 = 65 Wh 13 Product Safety & Regulations American National Standards Institute provides safety standards for all components in the solar power system. It is found in the UL Standard/Subject #458 under section 1.5. 14
System Description with Block Diagram Fig. 4 (Block diagram of solar system components) [4] 15 Trade Off Study Solar power system vs. engine-generator (gas powered) Solar power system has more advantages than an enginegenerator. o no fuel o no emissions o clean energy o low maintenance o easy to install o low recurrent costs 16
Trade-off Study Engine-generators provide electricity for places that have no power grids. o can be reliable when solar power cannot meet our electric needs o winter storms, windless day, battery charging o Noisy, dirt, fumes, not emission-free, high fuel costs 17 Required Resources Estimated cost of a solar power system is $10k to $100k. Requirements o where are you in the world o how much sun do you get per day o record power rating of all your appliances to find out how much power you require o residential installation times range from 3 days to 4 weeks, depending on the system size. 18
Gannt Chart 19 Estimated Project Cost Table 2: Total Cost of Components 20
Predicted Return of Investment Return of Investment = ($5000 $2,935.50)/$2,935.50 = 0.703 Local utility company pays you for any excess power that the battery produces. Save between $1,000 $2,000 per year on your electricity bill. 21 Potential Benefits Learn how to integrate your own residential solar power system. Gain knowledge of all components in a solar power system and know what their primary function is. Develop the skill of connecting components with wires and cables. Provides good experience in a potential career. 22
Risk Analysis Table 3: Risk analysis 1) Not having sufficient knowledge to complete the solar power system. 2) Installing the solar power system incorrectly. 3) Being to hasty in your decision making and not buying the proper equipment. 4) Not knowing the proper safety conditions when working with the equipment. 23