Presentation on theme: "Photovoltaic Solar Energy"— Presentation transcript:
1Photovoltaic Solar Energy Building Industry Technology AcademyWestern High School
2What is energy? Energy is often defined as the ability to do work. We commonly think of gas, electricity, or other fuelsSeveral different forms of energy, including kinetic, potential, thermal, gravitational, sound energy, light energy, elastic, electromagnetic, chemical, nuclear, and mass have been defined to explain all known natural phenomena.The first law of “Thermodynamics” is that energy cannot be created; only transferred between systemsIs electricity created?
3Solar Energy The Sun gives of two forms of energy for free Sunlight – solar radiationThis gives us both light and heatWithout it no life could exist on earthGravitational PullAlong with the moon’s gravitational pull is responsible for the ocean tides
5Free Energy Our Sun releases huge amounts of energy Our atmosphere, and clouds reflect or absorb about half of what is directed at usWhat hits the surface of the earth in one hour, more than equals the total energy requirements for the earth for an entire year!The sun is responsible for 99.9% of all renewable energy sources on earthWind, wave power, hydroelectricity, biomass & solarEven petroleum products originated from the sun
7The Solar Industry Thermal Photovoltaic Using the Sun’s heat to generate electricitySolar cookingSolar hot waterPhotovoltaicUsing solar radiation to generate electricitySolar calculators, light meters, & photovoltaic cells
8Photovoltaic From the Greek word phos = light & volt = electricity Solar cells are made from silicon crystals sliced thin and layeredSilicon is a semiconductor, electricity can pass but with high resistanceSolar radiation pushes electrons through
9Solar Cells About the size of your hand Electrical contacts both front and backPositive one side negative the otherCovered with antireflective glass
12Solar panels Most efficient solar panels available today 30 – 40% Average solar radiation is 1000 watts per meter2Output of that panel would be 300 – 400 wattsVery costly roughly $800 per wattUsually used in spaceCommon efficiency rating for panels 16%Much more affordable cost of $4 - $5 per wattInstalled cost of system $7 - $9 per watt is common
13Cost benefit analysis Systems are sold on a per watt of output basis Far easier to do a cost benefit analysisFirst question asked by a salesperson:How much did you pay for electricity last year?Easy to obtain information on current electric billSystem is sized to cover 70% to 100% of expected useMore is not better!Utility companies do not pay for extra – credits only
14Output of panels Factors change the output of panels Intensity of light sourceAngle of light sourcePanel temperature
15Intensity of Light Relative strength of solar radiation Strongest is at the equatorBlack dots represent theamount of sunlight neededto replace all of the world energy useWe receive 6000 times the amount of energy used
16Angle of light Best output is when light strikes at 90o to surface Orientation is usually southSuggested angle for best outputis the same as the latitude of locationSummer and winter changes in sunangleTracking systems are optimal
17Temperature High temperature will reduce the output of solar cells Cool temperatures are best, hot to the touch, is badElevated installations are suggested, with air circulation under panelsEvens the playing field,northern climes can still haveeffective PV systems becauseof cooler temperatures
18Inverter Panels generate DC current (like a battery) Inverter changes DC current to AC current and changes the voltage to 120/240 for home useSystems are tied into home electric panelDuring sunlight, if output is greater then home use, electricity is put into the power gridElectric meter will spin backwardsAt night, electricity will flow into house normallyThis system is called a “Grid tie system”
19Design Many homes are designed for “net zero” energy use Grid tie system, still use energy at nightAnnual energy use is a net zero as panel output equals total home use.Energy conservation is key to “net zero” designKeyword – SustainabilityTo live in a manner that is sustainable by the environment
20Questions What are the two types of energy we receive from the sun? What are two general types of commercial solar energy?What is the most common material used to make solar cells?For a home application, should the homeowner require the most efficient solar panels available? Why?Can you think of a way to analyze the cost of a system to see if it is cost effective to install in a building?
21Questions What factors should be considered in the cost analysis? Would Southern California be a suitable location for a solar system? Why?Use Google Earth or other mapping software off the internet to find out the Longitude and Latitude of this classroom.When considering roof pitch, orientation and shading, which rooms on campus would make ideal locations for a photovoltaic solar system?What information would you want to have from a client in order to prepare a bid to install a solar system?