Solar Project Yield Assessment

Solar Project Yield Assessment

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

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

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Solar Radiation Components

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Average GHI and DNI In India

Average DNI in India

Average GHI in India 3

Land Based Measurement •

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Thermal Pyranometers – These are also known as solarimeters and typically consist of a black metal plate absorber surface below two hemispherical glass domes in a white metal housing. Solar irradiance warms up the metal plate in proportion to its intensity Silicon Sensors – These are cheaper than pyranometers and consist of a PV cell, often using crystalline silicon. The current delivered is proportional to the irradiance. Well maintained land-based sensors can measure the solar resource with a relative accuracy of 3-5%.

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Land Based Measurement •

On‐site monitoring provides significant value to assessing a project’s potential, translating to higher confidence in energy 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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Data Summaries • • • • •

Site Description Solar Statistics Meteorological Statistics Monthly and Diurnal Trends O&M Summary

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Investment Grade Solar Resource Assessment

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Off Site Data • • • • • • • • •

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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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

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Data Sources for Solar Radiation • • •

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India Meteorological Department data from 23 field stations of the radiation network, 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 weather generator. This contains a database of ground station measurements of irradiation and temperature. In cases where a site is over 20 km from the nearest measurement station. Satellite-derived geospatial solar data products from the United States-based NREL. Annual average DNI and GHI, latitude tilt, and diffuse data are available at 10 km resolution for India,

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Energy Yield Prediction (RETScreen)

Location: Jodhpur (Rajasthan) India 14

Typical Horizontal Solar Irradiation in India

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Monthly Direct and Diffused Rations in Chennai

The annual mean GHI in Chennai is 2,021 kWh/m2. By optimally-orientating a fixed tilt plant, the yearly sum of global irradiation may be increased to 2,048 kWh/m2. Based on this resource, a 1 MWp plant with a PR of 80% will give an AC yield of 1,638 MWh. 16

Mean Daily GHI

Where there is significant uncertainty in the data sources, a short term data monitoring campaign may be considered. Short term monitoring (ideally up to one year in duration) may be used to calibrate long term satellite-derived data and increase the confidence in the long term energy yield prediction. 17

Energy Yield Prediction – How?

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 18

Energy Yield Prediction – Losses in the PV System

Air Pollution

Shading

Module Temperature

Incident Angle

Soiling

Module Mismatch

DC Cable Resistance

Inverter Performance

AC Losses

Degradation

Auxiliary Power

Downtime

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Typical Yield Assessment Report Results

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Typical Losses in the Plant

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Thank You 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.in Email: [email protected]

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