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UConn Spring Valley Farm Senior Design Solar Project (Spring 2015)

UConn Spring Valley Farm Senior Design Solar Project (Spring 2015). Stephanie Mesick Faheem Dalal Jorge Llivichuzhca. Service Learning. Critical Reflection

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UConn Spring Valley Farm Senior Design Solar Project (Spring 2015)

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  1. UConn Spring Valley Farm Senior Design Solar Project (Spring 2015) Stephanie Mesick Faheem Dalal Jorge Llivichuzhca

  2. Service Learning Critical Reflection • Our aim is to create a meaningful impact in the Uconn community by promoting renewable sources of energy to reduce the carbon footprint of the Spring Valley Farm. • The Spring Valley Farms, the Office of service learning, and School of Engineering are the main contributing factors to this effort. • This project has great significance since it can help the environment, incentivate the production of vegetables, help local economy, promote healthy eating. • The project is also a learning experience for us students with regards to dealing with multiple institutions and application of knowledge.

  3. Service Learning What we have learned • We are learning to work collectively as a team (research, organization, work ethic). • We have learned to collaborate with the farm manager, the program manager from the office of service learning, the director of Uconn floriculture, and other offices at Uconn. • Are learning the challenges that come with systems that utilize renewable sources of energy. • We have learned that renewable energy is a multi disciplinary field. • The market for renewable energy technology is larger than expected.

  4. Service Learning Future expectations • The solar/thermal systems will help reduce the carbon footprint of the farm to net-zero or close to net-zero. • The Uconn community will benefit more organic vegetables produced by the farm. • The farm economy and local economy will benefit thanks to the production of more vegetables and less consumption of nonrenewable resources. • The use of solar systems will promote a conscious and healthy consumption of energy. • We expect other institutions to follow our model to promote renewable sources of energy.

  5. 50 panel system (250W Panels)

  6. Net Zero system

  7. Product Specifications Maximum Power Point under Factory Test Conditions • The current drawn by a PV cell changes with varying light intensity. MPP is the point on an IV curve where the amount of current drawn keeps the voltage at almost peak levels. • A module’s rated power,PPMax, is the maximum power that can be extracted, assuming STC: • Air mass: 1.5 • Temperature of PV cells: 25 °C (77 °F) • Insolation level: 1000 W/m2 • Typical values of VPM: 30 V|PPMax = 250 W to 36 V|PPMax = 300 W • Typical values of IPM: 8 A|PPMax = 250 W to 9 A|PPMax = 300 W

  8. Product Specifications Maximum Power Point under Photovoltaic USA Test Test Conditions • Manufacturers may give a module’s PTC ratings or provide the module’s electrical properties at Nominal Operating Cell Temperature (NOCT). • NOCT and PTC are efficiency ratings of the module in real world conditions: • Air mass: AM1.5 • Ambient temperature: 50 °C • Insolation level: 800 W/m2 or 1000 W/m2 (specified by the manufacturer) • Wind speed: 1 m/s Typical values: 0.75PPMax≤ PNOCT ≤ 0.90PPMax

  9. Product Specifications Open circuit voltage (VOC) • VOC, the maximum voltage available from a solar cell, occurs at zero current. • Because a panel’s voltage will increase in cold weather,VOC, STC will be less than the panel voltage when the temperature is less than 25 °C (77 °F). • Typical values of VOC: 37 V|PPMax = 250 W to 46 V|PPMax = 300 W

  10. Product Specifications Short Circuit Current (ISC) • ISC, the largest current which may be drawn from the solar cell, occurs when the voltage across the solar cell is zero. • ISC mismatch between series-connected panels can cause power reductions. • ISC will be limited by the the cell with the lowest ISC rating. • At low voltages, the extra current generating capability of a good cell will be dissipated in the poor cell and potentially damage it. • Typical values of ISC: 8.8 A|PPMax = 250 W to 10 A|PPMax = 300 W

  11. Product Specifications Series Fuse Rating or Maximum Reverse Current Rating • UL Standard 1703 requires modules to have an external overcurrent protective device (OCPD). • The external series fuse is an OCPD used to protect the module from reverse currents. • Reverse current, or backfeeding, is most likely to occur if a string of modules stops producing power. • Typical values of max reverse current: 15 A|PPMax = 250 W to 25 A|PPMax = 300 W

  12. Product Specifications Temperature Coefficient and Maximum System Voltage (VSYS) • A panel’s voltage will increase during cold, sunny conditions. • The TKVOC coefficient tells how much a module’s voltage will increase per ͒C below STC of 25 ͒C. • TKVOC is given as %/ ͒C or V/ ͒C • NEC Article 690.7 states that if the manufacturer provides a temperature coefficient of open-circuit voltage (TKVOC) , it must be used when computing the maximum PV array voltage.

  13. Product Specifications Temperature Coefficient and Maximum System Voltage (VSYS) Ex. TKVOC for the LG 250 W Mono panel is -0.36 %/ ͒C and VOC, STC is 37.1 V. The record low temperature for Mansfield, CT is -29 ͒C (-20 ͒F).

  14. Product Specifications Common Product Certifications

  15. Product Specifications Common Product Certifications

  16. Week of 2/23

  17. Collectors Distance

  18. Collectors distance Collector tilt: φ=35 Collector height: x = 8ft Solar azimuth: ψ=140.9° Solar altitude angle: α=14.2° Shadow Distance: D’ Minimum collector distance: D Collector height at angle: h Source: NOAA Source Calculator

  19. Collector Efficiency Source: Central Solar Hot Water System Design Guide

  20. Collector piping arrangements Source: Central Solar Hot Water System Design Guide

  21. Collector flow system For best results the collector flow systems should be kept at a low flow system: ~0.37 gal/sq ft*h (15 l/m2 ) Advantages: • Lower investment costs due to smaller pipe sizes required. • Lower piping lengths, as more collectors are connected in series (lower investment) and reduced heat losses. • Smaller pump requirements (lower investment), which use less pump energy (lower operation costs) due to lower volume flow. • Requirement for less fluid in the solar loop, and consequently less glycol (lower investment). • Quicker response to achieving the target temperature in heat storage tanks including those using stratified charging . • Ability to achieve a useful temperature in a single flow cycle a greater percentage of the time.

  22. Collector antifreeze When using a water-glycol mixture there are few things to consider: • The heat capacity of the fluid is reduced causing a reduction in efficiency of the collector field. In addition, for a comparable mass flow more pump energy is needed. • Glycol deteriorates when heated up to common collector temperatures. Deteriorated glycol forms solid particles that can block and even destroy the collector loop therefore the glycol mixture then must be replaced.

  23. Air elimination

  24. Calculations of Greenhouse Gas Emissions • Goal: To convert electrical consumption in kilowatt-hours into units of CO2 emissions avoided from the PV system. • The U.S. Environmental Protection Agency uses the “Emissions & Generation Resource Integrated Database (eGRID) U.S annual non-baseload output emission CO2 rate” to determine equivalencies for emissions reductions. • The EPA assumes that renewable energy systems only impact “non-baseload emissions” (the emissions from power plants that are brought online as necessary to meet demand). • The emission factor does not account for greenhouse gases other than CO2.

  25. Air elimination Things to consider: • When the piping system is filled with the heat transfer fluid air is pushed out of the pipes as the fluid enters therefore air vents are needed. • Air vents are valved openings in the pipe system are installed at high points. • When fluid begins to be released at these high points the valve is closed and the captured air is removed. • This air removal exercise must be done not only at the initial fluid fill and short time after operation begins and then on a routine basis thereafter.

  26. Metrics Used to Evaluate Costs and Performance of Renewable Power Technologies Analyzing the costs of generating electricity from PV • Costs that can be examined include: 1) equipment costs (e.g. PV modules), 2) total installed cost (e.g. financing costs, fixed and variable operating and maintenance costs, fuel costs), and 3) levelized cost of energy (LCOE). • Despite declines in PV system cost, the levelized cost of electricity (LCOE) of PV remains high. • Further analysis can take into account emissions (CO2)pricing.

  27. Metrics Used to Evaluate Costs and Performance of Renewable Power Technologies Analyzing the costs of generating electricity from PV • “The levelized cost of electricity (LCOE) of PV is the price of electricity required for a project where revenues would equal costs, including making a return on the capital invested equal to the discount rate.” • An electricity price above this would yield a greater return on capital. • An electricity price below this would yield a lower return on capital or even a loss.

  28. Metrics Used to Evaluate Costs and Performance of Renewable Power Technologies

  29. Spring Valley Farm Solar Project Senior Design Weekly Meeting April 7, 2015

  30. Solar Thermal System Diagram

  31. Solar Thermal System Cost Analysis Propane Rate: $3.37 Propane Annual Inflation Rate: 7.35%

  32. Solar Thermal System Cost Analysis Option 1 Table 1. This table shows the cost analysis of system option 1 with with a return of investment of 122%

  33. Solar Thermal System Cost Analysis Option 2 Table 2. This table shows the costa analysis of system option 2 with -14% return of investment.

  34. Greenhouse emissions Greenhouse emissions gas (CO2) saved = 26 tons = 19.5 tons of waste sent to a landfill

  35. Residential Solar Systems in CT • The Clean Energy Finance and Investment Authority provides information on installers and costs over the period: 2008 - February 2015. “The information presented below is for comparative purposes only. Actual installation costs vary depending upon site specific conditions, type of equipment specified, and accessories or extra features such as a tracking array, etc. Consumers are encouraged to do their own due diligence when making this major buying decision. All information presented is derived directly from received incentive applications and may not reflect final installation costs.”

  36. Residential Solar Systems in CT • Using “Total System Cost” and “System Size (kW)” for 1,538 Connecticut residents who had systems installed through the Residential Solar Investment Program between 2014 and 2015, it was found that the average cost was $4.36 per Watt. • The 12.5 kW system at Spring Valley Farm could cost $54,500, based on this data.

  37. Projections of Grid-Tied PV System Output Over Twenty Years . Table 1. A 12.5 kW array, consisting of fifty 250 W panels, has an initial power degradation of 3% and subsequent degradation of 0.7% per year. It is estimated that in its first year, the system would output 19,218 kWh and reduce CO2 emissions by 13.2 metric tons.

  38. Cost Analysis of Grid-Tied PV System over Twenty Years . Table 2. Estimating that the total cost of the system is $54,500, that residential electricity increases at the same rate as it did between 2001 and 2014, with 3% inflation, the farm will not have to purchase electricity for the first ten years after installation. Deducting the amount of money that would have been spent on grid-generated electricity in addition to the amount of money paid to the farm by CL&P, the system will be paid for in its fifteenth year.

  39. Electricity Expenses With and Without 12.5 kW PV Array Fig.1 . Estimating that the total cost of the system is $54,5000 and that residential electricity increases at the same rate as it did between 2001 and 2014, the farm will not have to purchase electricity for the first ten years after installation.

  40. Solar systems across the United States • Reported system prices of residential and commercial PV systems declined 6%–7% per year, on average, from 1998– 2013. • 12%–15% from 2012–2013, depending on system size. • Reported pricing for PV system installations completed in 2013, based in part on data reported to PV incentive programs: • Residential and small commercial (≤10 kW) was $4.69 /W (median) • Large commercial (>100 kW) was $3.89/W (median) • Modeled solar PV system prices, using industry validated tools, quoted in Q4 2012 (and expected to be installed in 2013): • Residential (5 kW) was $3.71/W • Commercial (223 kW) was $2.61/W

  41. Service Learning: Educating SVSF Students on Solar Energy Possible Topics to Include in a Presentation • The concept of irradiance. • The solar energy available to the farm over the course of a year. • Overview of the farm’s electric and propane usage in terms of emissions and dollars. • Explanation of the photovoltaic effect. • Solar cell materials and mechanismfor generating electricity. • Sizing methods for both systems • The need for a grid-tied system,given the difference between potential production and consumption over the course of the year. • The concept of dc/ac inversion. • The environmental impact / life-cycle analysis of PV and solar thermal.

  42. Placement Approximate array location at Spring Valley Farm. Given a required array area of 808 ft^2 (75 m^2), panel dimensions of 5.35 ft x 3.25 ft (1.63 m x 0.996 m), and 9 ft of space between rows, the array will be 50 ft x 28 ft, or 1400 ft^2 (15.24 m x 8.5 m, or 130 m^2).

  43. Placement • Similarly, the 50 ft x 28 ft array could be oriented parallel with the greenhouse.

  44. area for array ex panel dimensions = 1.63m x .996m 9 ft = 2.7432m length of string = .996m x 7 = 6.972m area between rows = 6.972x2.742 = 19.2m^2 8 strings→ 7 spaces between rows: 19.2 x 7 = 134m^2 134m^2 +74.608m^2 = about 200m^2 7strings→ 6 spaces between rows: 19.2 x 6 = 115.2m^2 115.2 + 65.282 = 180.482 z z = xcos(35) = 1.633m(cos35) =1.337m Area on ground per panel = 1.337m x .996m = 1.332m^2 7 panels per string: 1.332m^2 x 7 = 9.326m^2 7Strings = 9.326m^2 x 7 = 65.282m^2 8 strings = 74.608m^2 String of 7 panels Area between two strings or rows String of 7 panels

  45. z

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