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					</table><p>India’s average solar irradiance <a href="https://www.mercomindia.com/high-irradiance-low-installations-the-solar-gap-in-eastern-and-central-india" target="_blank" rel="noopener">ranges</a> from 3.5 kWh/m²/day to 5.5 kWh/m²/day. Differences between satellite-derived irradiance estimates and actual ground conditions can create uncertainty in generation forecasts and financial models, affecting project economics and investment decisions.</p>
<p>Irradiance data discrepancies can distort generation forecasts, affecting project performance and economics. Overestimated irradiance can inflate expected energy output, while lower actual generation can reduce revenues, cash flows, returns, and bankability. Further, inaccurate readings can also mask technical underperformance and hinder plant optimization.</p>
<p>Developers and technical consultants address these discrepancies by comparing multiple datasets and validating satellite estimates against ground measurements before finalizing resource assessments.</p>
<p><strong>Ground Validation</strong></p>
<p>Companies such as <a href="https://abenergia.co.in/" target="_blank" rel="noopener">AB Energia Solutions</a>, a solar engineering, procurement, and construction company, identify and quantify differences early, assess the suitability and representativeness of available data, and calibrate the resource assessment where required.</p>
<p>According to Abhijeet Sengupta, Chief Technology Officer AB Energia compares irradiance data from multiple independent sources, including ground-measured data wherever available, to identify site-specific variations. The company then uses the most representative and technically appropriate dataset for generation modeling.</p>
<p>Nishant Sood, MD at solar commercial and industrial solar solutions provider <a href="https://www.candi.solar/in/our-work" target="_blank" rel="noopener">Candi Solar India</a>, said the company uses both ground-based and satellite irradiance data because the two have different error profiles and require validation. For ground-based data, its technical teams verify that sensors and physical devices are calibrated and functioning properly and check the geometric relationship between global horizontal irradiance, direct normal irradiance, and the solar zenith angle.</p>
<p>For satellite data, Candi Solar uses aggregated sub-hourly data over longer intervals to reduce spatial and temporal noise. It continuously compares satellite and sensor measurements to determine whether deviations fall within expected ranges and can be explained by different error profiles. The third-party provider carries out satellite-data validation.</p>
<p>According to a source at public sector energy company <a href="https://sjvn.nic.in/" target="_blank" rel="noopener">SJVN</a>, at least 12 months of continuous ground measurements help capture seasonal variations in irradiance, cloud cover, and atmospheric conditions. For large or financially sensitive projects, 18 to 24 months of quality-controlled ground data can provide better validation. The objective is to validate long-term satellite resources against site-specific measurements rather than replace satellite data with ground measurements.</p>
<p><strong>Data Discrepancies</strong></p>
<p>The discrepancy between ground-measured irradiance and satellite communication (SATCOM)-based solar resource mapping in India is location-specific and depends on satellite data quality, atmospheric conditions, terrain, and the availability of reliable ground measurements.</p>
<p>SATCOM datasets provide modeled estimates instead of direct measurements at project sites. Differences can arise from cloud cover, aerosols, dust, humidity, local topography, and satellite data resolution.</p>
<p>The SJVN source said discrepancies can be smaller at sites with uniform terrain and stable atmospheric conditions and more pronounced in areas with complex terrain, high aerosol loading, or rapidly changing weather.</p>
<p><strong>Regional Variations</strong></p>
<p>Rapidly changing clouds may not always be captured accurately at a project’s precise location and time. Dust, smoke, aerosols, pollution, humidity, water vapor, ozone, terrain, and errors in satellite model inputs can also affect estimates. Ground sensors measure irradiance at specific locations, while SATCOM data usually represents irradiance over a grid or defined area.</p>
<p>According to the SJVN source, high aerosol and pollution levels in the Indo-Gangetic Plain can cause irradiance to be overestimated or underestimated if aerosol conditions are not represented accurately. Dust and desert aerosols are important factors in Rajasthan and Gujarat. Complex terrain can create local variations in the Himalayas and other hilly regions, while the Western Ghats and Northeast can present challenges due to orographic clouds and localized weather. Coastal and floating solar sites can also be affected by humidity, fog, mist, cloud cover, and changing atmospheric conditions.</p>
<p>Most of India <a href="https://www.mercomindia.com/indias-solar-irradiation-below-normal-in-2025-global-anomalies-reach-20" target="_blank" rel="noopener">recorded</a> below-normal solar irradiation in 2025, ranging from below 1% to less than 8% of the norm, with southwest coastal anomalies below 10%. An unusually long monsoon largely contributed to this development. Globally, irradiation anomalies ranged from below 14% to 20% above long-term averages.</p>
<p><strong>Project Performance</strong></p>
<p>If irradiance assumed during project planning is consistently higher than the resource available at the site, expected generation and capacity utilization factor (CUF) can be overestimated.</p>
<p>Sengupta said material discrepancies between irradiance datasets can influence estimated energy generation and a project’s CUF.</p>
<p>Sood said Candi Solar does not consider CUF a useful plant-level performance metric because it is too broad. Irradiance deviations can proportionally affect technical performance and, depending on contractual terms, commercial performance. Inaccurate readings can also hinder performance optimization by masking technical underperformance or indicating underperformance where none exists.</p>
<p><strong>Financial Impact</strong></p>
<p>Discrepancies in irradiance estimates can affect project financial modeling and bankability because expected generation determines projected electricity sales and revenue.</p>
<p>According to SJVN, sustained generation below projections can reduce revenues and cash flows, affecting expected financial returns and a project’s ability to meet financial obligations.</p>
<p>Sengupta said even relatively small variations in estimated generation can affect projected revenues, cash flows, and project returns.</p>
<p>Sood said irradiance is among the most sensitive inputs for generation estimates, which are key inputs for project financials. The irradiance assumption used in project financials depends on market pricing dynamics, financial risks, and scenario analysis.</p>
<p><strong>Validation Standards</strong></p>
<p>The SJVN executive said developers and lenders should avoid relying on a single meteorological or satellite-derived dataset. Two or more independent sources should preferably be compared, with reliable ground measurements used for validation wherever available. Where datasets differ significantly, a reasonable and appropriately conservative estimate should be used for energy yield assessment and financial modeling, with the associated uncertainty reflected in the assessment.</p>
<p>Stakeholders suggest that the Central Electricity Authority could introduce uniform irradiance-related guidelines as India pursues its target of achieving 500 GW of installed non-fossil fuel-based electricity capacity by 2030.</p>
<p><strong>Technology and Data Investments</strong></p>
<p>While advances in satellite sensors, spatial and temporal resolution, atmospheric modeling, cloud detection, aerosol estimation, artificial intelligence, and machine learning have improved the accuracy and consistency of satellite-based solar resource assessments, ground validation remains important because satellite models cannot always fully capture local terrain, microclimates, and other site-specific conditions.</p>
<p>Stakeholders call for expanding reliable ground-based measurement stations across climatic and geographical regions, regularly calibrating and maintaining equipment, and standardizing data collection, validation, quality assessment, and reporting. Investment is also required to develop accessible long-term solar resource databases, better integrate ground and satellite datasets, and strengthen institutional capacity and technical expertise.</p>


Satellite-Ground Irradiance Gaps Raise Risks for Solar Projects in India


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					</table><p>Kolkata-based solar module manufacturer <a href="https://www.vikramsolar.com/" target="_blank" rel="noopener">Vikram Solar</a> has secured an order from <a href="https://abenergia.co.in/" target="_blank" rel="noopener">AB Energia Solutions</a> for the supply of 200 MW of solar modules, valued at approximately ₹2.73 billion (~$32.63 million).</p>
<p>The agreement will see the modules deployed across Maharashtra, Madhya Pradesh, and Gujarat.</p>
<p>According to the company, the modules covered under this agreement are Vikram Solar’s M10R N-Type TOPCon modules rated at 590 W and above.</p>
<p>Deliveries under this contract are scheduled to begin in September 2025 and will continue through March 2026.</p>
<p>The order is a one-time supply agreement and has been placed with AB Energia, a domestic entity specializing in end-to-end engineering, procurement, and construction solutions for commercial and industrial solar projects.</p>
<p>Vikram Solar operates 4.5 GW of installed solar module manufacturing capacity, producing N-Type and HJT bifacial modules across its facilities in Falta SEZ, Kolkata, West Bengal, and Oragadam, Chennai, Tamil Nadu.</p>
<p>Recently, Vikram Solar <a href="https://www.mercomindia.com/vikram-solar-module-supply-order-lt-construction" target="_blank" rel="noopener">received</a> an order to supply 336 MW of solar modules from L&amp;T Construction for the latter’s project in the Khavda Renewable Energy Park. As part of this order, Vikram Solar will supply its Hypersol G12R modules, built on N-type technology.</p>
<p>As of August 13, 2025, Vikram Solar has an enlisted capacity of 4.3 GW under the Ministry of New and Renewable Energy’s Approved List of Models and Manufacturers for solar modules.</p>
<p>Vikram Solar’s initial public offering was <a href="https://www.mercomindia.com/vikram-solars-ipo-oversubscribed-by-over-54-times" target="_blank" rel="noopener">oversubscribed</a> 54.63 times at the end of the bidding window on August 21, 2025. The proceeds from the fresh issue will be utilized for capital expenditure through investment in its subsidiary, VSL Green Power. Of the total amount, ₹7.93 billion (~$92.42 million) will be deployed for partial funding of an integrated solar cell and module manufacturing facility.</p>


Vikram Solar Secures ₹2.73 Billion Module Supply Order from AB Energia

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