1Firstgreen Consulting Pvt Ltd. B 1202 Millennium Plaza, Sec 27 Gurgaon 122002

Solar Project Yield Assessment

Workshop on Solar Power Project Development, Sept 20-21, 2012

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Solar Radiation Components

Average GHI in India Average DNI in India

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Average GHI and DNI In India

• Thermal Pyranometers – These are alsoknown as solarimeters and typicallyconsist of a black metal plate absorbersurface below two hemispherical glassdomes in a white metal housing.

• Solar irradiance warms up the metalplate in proportion to its intensity

• Silicon Sensors – These are cheaper thanpyranometers and consist of a PV cell,often using crystalline silicon.

• The current delivered is proportional tothe irradiance.

• Well maintained land-based sensors canmeasure the solar resource with arelative accuracy of 3-5%.

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Land Based Measurement

• On‐site monitoring provides significant value to assessinga project’s potential, translating to higher confidence inenergy estimates.– Accurate Representation of the Project Site

– Customizable for Various Technologies (e.g., PV or CSP) and Various Users

– Flexible Equipment Options and Costs

– Small Environmental Footprint

– Straight‐Forward Installation & Operation

– Self‐Contained Communications and Power Supply

Maintenance– Regular Schedule

– Clean and Level Instrumentation

– Verify Site Security and Overall Conditions

Data Validation and Quality Control– Regular System and Data Inspection

– Comparison with Reference Data

– Extreme or Suspect Values

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Land Based Measurement

• Site Description

• Solar Statistics

• Meteorological Statistics

• Monthly and Diurnal Trends

• O&M Summary

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Data Summaries

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Investment Grade Solar Resource Assessment

• Site Location and Exposure

• Proximity to Project Site

• Reference Station

• Period of Record

• Data Trends

• Data Recovery Rate

• Site Maintenance

• Instrument Calibration

• Correlation Between Sites

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Off Site Data

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Adjusting to the Long Term

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Data Uncertainty

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Uncertainty in Long Term Projections

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Uncertainty in Energy Yield Prediction

• India Meteorological Department data from 23 field stations of the radiationnetwork, measured from 1986.

• NASA’s Surface Meteorology and Solar Energy data set. This holds satellite –derived monthly data for a grid of 1°x1° covering the globe from 1984.

• The METEONORM global climatological database and synthetic weathergenerator. This contains a database of ground station measurements ofirradiation and temperature. In cases where a site is over 20 km from thenearest measurement station.

• Satellite-derived geospatial solar data products from the United States-basedNREL. Annual average DNI and GHI, latitude tilt, and diffuse data are availableat 10 km resolution for India,

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Data Sources for Solar Radiation

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Location: Jodhpur (Rajasthan) India

Energy Yield Prediction (RETScreen)

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Typical Horizontal Solar Irradiation in India

The annual mean GHI in Chennai is 2,021 kWh/m2. By optimally-orientating afixed tilt plant, the yearly sum of global irradiation may be increased to 2,048kWh/m2. Based on this resource, a 1 MWp plant with a PR of 80% will give an ACyield of 1,638 MWh.

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Monthly Direct and Diffused Rations in Chennai

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Mean Daily GHI

Where there is significant uncertainty in the data sources, a short term datamonitoring campaign may be considered. Short term monitoring (ideally up to oneyear in duration) may be used to calibrate long term satellite-derived data andincrease the confidence in the long term energy yield prediction.

Sourcing measured environmental data

Calculating the irradiation incident on the tilted collector plane

Modelling the performance of the plant with respect to varying irradiance

Applying losses

Applying statistical analysis of resource data and assessing the uncertainty in input values

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Energy Yield Prediction – How?

Air Pollution ShadingModule

TemperatureIncident Angle

Soiling Module MismatchDC Cable

ResistanceInverter

Performance

AC Losses Degradation Auxiliary Power Downtime

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Energy Yield Prediction – Losses in the PV System

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Typical Yield Assessment Report Results

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Typical Losses in the Plant

FirstGreen Consulting Private Limited

Gurgaon: U 28A/3 FF, DLF Ph III, Gurgaon – 122002, India Tel.: (+91) 124 4063031, 9899295854 Fax: (+91) 124 424 1751

Web: www.firstgreenconsulting.inEmail: sanjayv@firstgreenconsulting.in

Thank You

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