Irradiance. Solar Fundamentals Solar power investment decision making

Transcription

1 Solar Fundamentals Solar power investment decision making Chilean Solar Resource Assessment Antofagasta and Santiago December 2010 Edward C. Kern, Jr., Ph.D., Inc.

2 Global Solar Radiation

3 Solar Power is Changing Rapidly Technology, markets, investments, players Regulations and Incentives Public awareness, pro-activism and potential backlash Climate stabilization policies Environment protection policies Economic development policies Energy security policies

4 Solar Power Technologies Concentrating Solar Power (CSP) Flat Plate Photovoltaic (PV)

5 Concentrating Solar Power Technologies Parabolic Trough Linear Fresnel Power Tower Dish Sterling Engine Concentrating PV

6 Andasol CSP Plants Guadix, Andalucia

7 Andasol CSP Steam Power Blocks

8 Andasol CSP Linear Parabolic Line Focusing

9 Solar Photovoltaic Technologies Crystalline Silicon (c-si) Preferred for rooftop applications Thin Film (a-si, Cd-Te, CIGS) Favored in utility scale applications Common focus to drive down cost per watt installed

10 Crystalline and Thin Film PV Manufacturing Crystalline PV Module (Evergreen Solar) Thin Film PV Module (Moser Baer)

11 Rapid Global Growth of Solar PV as Grid-Tied Solar Scales (Historical and Forecast) Solar PV is now the fastest growing (in % terms!) power generation technology with a 70% increase in 2008 to reach 13 GW installed

12 PV Materials, Cells and Modules Crystalline silicon solar cells Most widespread use, most field experience Preferred for rooftop and remote power (higher efficiency) Single and multi-crystalline manufacturing processes Mature with limited potential for cost reduction Thin-film solar modules Silicon and other semiconductor materials Preferred for large grid solar power; lower cost, lower efficiency More potential for significant cost reduction

13 20 MW PV Plant near Valencia

14 PV Plants can look like lakes

15 PV Design Process Terminology used with PV technology and systems development Solar energy resources Relationships between efficiency and required land/roof area Prices for the glass, copper, concrete are needed Physics underlying power generation (yield) calculations Infrastructure requirements, site constraints and environmental influences (pro and con)

16 PV Project Development Stages Develop Simple Cost/ROI Model Exercise the cost model to check investment Define system size, location and solar resources Develop design concept and a performance model Estimate land, labor and operation costs

17 Solar PV Power Plant Operations Things that can go badly wrong (rare) Power conversion equipment failure High temperature failures in electrical junctions/wiring High wind-, snow- or ice-caused failures in PV panels or structures Electrical fires in modules and wiring (very rare) Things that can go a little wrong (common) Dirt, dust and pollen soiling, snow and ice shading Miscalculated solar energy resources

18 Losses in Efficiency Depends on PV material type Temperature rise reduces output; passive cooling is good Spectral impacts Shading losses Wiring (copper) I 2 R losses Maximum power point tracking losses Transformer losses Soiling losses (cleaning impacts)

19 Terminology Peak Watts (rated Watts) Power produced in nominal full sunlight of 1000 W/m^2 irradiance with cells operating at 25 C Efficiency Ratio of input to output; modules: irradiance to dc power (5-20%); inverters dc to ac power (90-98%) Temperature Thermal coefficients for thin-films Spectral and diffuse light response differs between technologies Product differentiation/marketing spin (beware) Know how percentage differences translate into absolute performance differences

20 Solar Resources and insolation (power and energy units) Beam, diffuse, total and Plane of Array irradiances Point focus and line focus concentrators Flat panel fixed and tracking Array peak Watts (PV dc or thermal collector field) System rated Watts (PV ac inverter or thermal turbines) Fixed, one and two axis tracking yield differences from flat panel systems (approximately ~20% and ~40% more solar radiation enters the collectors; but at increased cost and greater land area requirements)

21 Solar Energy (Above Atmosphere) Above the atmosphere about 1.4 kw/m 2 facing the sun (33.6 kwh/m 2 in 24 hours) Earth s rotation cosine/nighttime losses reduce to 7.6 hours equivalent Total is about 10.7 kwh/m 2 per day parallel to the earth s surface Absorption, reflection and scattering by the atmosphere; typically 4 to 6 kwh/m 2 on earth s surface (Atacama is NOT typical, range 6 to 8 kwh/m 2?)

22 Atmospheric Scattering/Absorption Without an atmosphere (e.g. moon) there is just direct (sunlight) irradiance On earth scattering creates diffuse (skylight) irradiance Typical clear day, bright day: W/m 2 direct W/m 2 diffuse 12/17/

23 Practical Solar Insolation Direct normal and diffuse irradiance Total irradiance nominally 1 kw/m to 1000 W/m 2 for direct (beam) 200 to 100 W/m 2 from diffuse Hours of Sunlight Effective hours at the nominal 1 kw Typically 4 to 6 hours per day annual average, perhaps to 8 in high deserts (Atacama) Average, about 5 kwh/m 2 per day

24 Shadowband Radiometer Testing Colleagues at Plataforma Solar Almeria

25 Resource Assessment at University of Jaen Studying the accuracy of day ahead resource predictions

26 Minute to Minute and Hourly

27 Daily Variations

28 Basic Power Yield Modeling Really Simple Spreadsheet model PV Watts model from NREL (USA) RetScreen model from Natural Resources Canada PVSYST model from Univ. of Geneva DC Power AC Grid Power Sunlight

29 NREL s PV Watts Calculator Component Derate Factors PVWATTS Range Safe PV module nameplate DC rating Inverter and Transformer Mismatch Diodes and connections DC wiring AC wiring Soiling System availabilty Shading Sun-tracking Age Overall DC-to-AC Derate Factor , Inc.

30 Project Economics Negatives Positives

31 Simple PV System Cost Model Design and Construction $/Watt(DC) PV module unit price $ 2.75 Array structure and wiring $ 0.20 Power inverters $ 0.20 Plant planning costs, fees, permits $ 0.15 System construction $ 0.20 Total Capital Cost $/Watt (DC) $ 3.50

32 PV System Performance Model Finance and Operation Cost of money (%/yr) 5% Annual O&M (% of capital cost) 0.5% Plant module DC to inverter AC efficiency 80% Generation capacity factor 20.0% Annual production (kwh/w) 1.40 Annual plant cost ($/Watt DC) $0.28 Average kwh cost ($/kwh) $0.20

33 Good Practice Avoid novel technology, be conservative Use proven solar and inverter technology Stress importance of long-term goals Initial projects lay foundations for future Track and report metrics for multiple stakeholders Include outreach to policymakers and power sector

34 Summary Solar Resource Solar Resource Air temperature PV Technology Modules, inverters and balance of systems Maintenance Production Economics Predictable maximum power generation by hour Forecasted losses from clouds Generation value by hour, day, and season

35 Uncertainties: Will financial incentives continue with sovereign debt increasing? Will progress toward grid-parity continue and maintain public support? Will new, lower-cost technologies make today s systems obsolete and/or will prices drop so fast that buyers wait? Can more accurate site-specific yield projections increase investment return (ROI) certainty?

36 Contact Details Edward Kern, Inc. 36