The document focuses on solar resource assessment techniques, emphasizing land-based measurements using thermal pyranometers and silicon sensors to assess solar radiation components in India. It highlights the significance of on-site monitoring for accurately estimating a project's energy potential and details the various data sources and validation processes involved. Additionally, it discusses typical solar irradiation metrics for locations like Chennai and suggests short-term data monitoring to enhance long-term predictions.

1. Solar resource Assessment
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2. Solar Radiation Components
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3. Average GHI and DNI In India
Average GHI in India Average DNI in India
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4. Land based measurement
 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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5. 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
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6. On Site measurement
 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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7. Data Summaries
 Site Description
 Solar Statistics
 Meteorological Statistics
 Monthly and Diurnal Trends
 O&M Summary
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8. Investment grade solar resource assessment
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9. 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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10. Adjusting to the long term
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11. Data uncertainty
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12. Uncertainty in long term projections
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13. Data sources for solar radiation
 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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14. Typical horizontal solar irradiation in India
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15. 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.
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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.
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17. Thank You
FirstGreen Consulting Private Limited
Gurgaon:
206, Tower B, Millennium Plaza, Sec 27, Gurgaon – 122002,
India
Tel.: (+91) 124 424 1750 , 9899295854
Fax: (+91) 124 424 1751
Web: www.firstgreenconsulting.in
Email: sanjayvashishtha@gmail.com
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