Analytical-Diagnostic Monitoring of Solar Arrays..continued
May 15, 2012, 6:54 a.m.
Title: Analytical-Diagnostic Monitoring of Solar Arrays with Proxy Irradiance Data 1 & 2 of 5 subtitle: A resource to enable checkups on performance of solar sites without sensors & instrumentation It is not well publicized, but a real ‘pain’ for PPA, or ‘Lease’ solar energy providers, that is unknown, or only learned after the fact, from monthly utility bills and PPA statements. My own personal observations over hundreds of solar projects show half of solar arrays under perform, by 20 to 30 %, from their practical capacity, nominally pegged at 77% of maximum DC rating, or PTC rating for California. Further evidence comes from the fact many projects are oversized by 10 to 30%, as a cushion against penalty clauses in PPA contracts. In terms of dollars these unrealized energy production amount to $5B for all installed arrays by end of 2011. These long term contracts with performance guarantees present unknown risk for investors and owners of these assets. Our analytical tools, and diagnostic capability being developed will address these waste and help detect and quantify performance deficiencies in real-time, or via web machine-to- machine data links on few times a day basis to keep a vigilant watch over the solar generator sites’ performance. PVwizard is a platform that combines desciplines of physical & computer sciences, knowledge, photovoltaic and data engineering in a synergistic meshing of sensor instrumentation, database tables, algorithmic and inference engine, inter-server communications and advanced web features to deliver critical information to help maintain optimal operation of solar power generators everywhere. part 2 of 5: What’s unique about PVwizard? Key features of our PVWizard analytical capabilities are: Comprehensive mathematical model, adapted from Sandia Labs, and expanded to include fault sources Low-cost hybrid analog and digital sensor signal preprocessor that captures the minute changes in solar array strings. Advanced machine-learning diagnostic algorithms with heuristics that learns to gain better and better accuracy and confidence in its diagnostics. Both on-demand web-interactive(free) and in-the-background, including real-time access of analytical and diagnostics, alerting, warning, and alarms are available. We listened to solar contractors and monitoring companies, and arrived at these features.. In the first place, the sensors and instrumentation are focused on the DC characteristics aimed at being able to perform diagnostics based on electrical changes that are reflective of system conditions and responses to fault sources. What’s unique about PVwizard --to be continued, part 3 of 5, Rationale for PVwizard part 4 of 5, Application of PVwizard Features part 5 of 5 Work-in-Progress Future Enhancements
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