By Mark Barron, business development manager for Seaward Group USA
Reduced government support for new projects, the maturing of schemes into post warranty stages and industry consolidation leading to larger portfolios have all come together to emphasize the need for effective asset management systems capable of ensuring optimal financial performance of solar PV installations.
Larger utility and commercial projects have always taken a more sophisticated view of O&M to meet the long terms performance needs associated with financial modelling and initial project investment decisions. Now, residential solar installers are increasingly adopting O&M strategies to protect asset values, meet warranty terms for new projects and monitor component performance at the end of existing warranty periods.
Other trends are also increasing the focus on O&M. The growth of a secondary market, particularly in Europe where solar PV assets are sold to new investors, has resulted in closer scrutiny of performance and reliability of generation. Elsewhere, third-party ownership financing, including power purchase agreements (PPA) and leases, also highlights the need for efficient O&M arrangements.
Factors such as these have seen large portfolios of solar PV assets coming into the hands of a relatively few operators and owners, and this is also impacting the O&M market. The economies of scale associated with multi-megawatt utility- and commercial-scale projects tend to favor the development of in-house project maintenance skills and resources. Alternatively, those bringing together several smaller sites, perhaps with a broad geographical spread, may prefer to outsource O&M support from specialist contractors.
Whatever the structure or strategy, the aim of an effective solar O&M strategy must be to protect the value of the asset by optimizing plant production and reducing the financial risk for owners and investors.
Central to these emerging trends is the recognition that the use of more efficient solar PV O&M technologies and working practices are now vital. This not only requires accurate fault diagnosis and repair, but also associated capabilities such as remote monitoring, data collection and analysis, and the transfer of on-site measurements and results to headquarter-based monitoring centers.
Innovation in solar technology and management (T&M) technology is now helping meet this challenge with new approaches that combine consistent monitoring systems across different sites with improved data handling and standardized reporting formats so operational efficiencies can be maintained.
The power of solar PV system data
Solar PV component or system faults leading to performance losses need to be minimized over the lifespan of the plant. Central to meeting this need is the ability to identify, diagnose and rectify solar PV system faults quickly and efficiently.
PV plant checks to verify performance and confirm the viability of original financial models have become essential. Changes to feed-in-tariffs have also created a need for owners and operators to perform detailed performance, revenue and financial analyses to ensure projects can continue to meet debts and financing requirements–particularly during low irradiation months.
Against this background, periodic electrical testing is the proven method to establish the reasons for any identified underperformance and to enable timely mitigation measures to be applied.
In all cases, to limit revenue risks, preventative maintenance incorporating verification testing with a mobile tester will enable any degradation of modules to be highlighted and controlled and other system component faults to be identified.
However, alongside on-site testing, the importance of collecting, transferring and managing system data is now a fundamental requirement. In particular, to enable the efficient performance optimization of larger PV portfolios, central control centers are increasingly being utilized by operating or management companies to monitor power outputs.
Linked weather and output data from individual plants enables PV power portfolios to be closely monitored and can also include a range of fault detections and other alarms to highlight below-expectation energy outputs. When under-performance is detected, central maintenance staff can alert on-site (or local) O&M contractors for remedial actions to be taken in the fastest and most efficient way possible. However, once on site, there is also a need for system measurements and field test data to be fed back into the central database for a completely closed information loop and to enable the most appropriate interventions or remedial actions to be taken.
Solar PV test equipment
There are many instruments available that are sold under the title of “solar testers,” so it is vital to ensure the instruments utilized in O&M services are capable of performing all of the tests required. The absolute minimum testing that needs to be undertaken involves continuity measurements, open circuit voltage, short circuit current, insulation and irradiance.
The new PV210 solar tester with android app
For fault finding and diagnosis, other test instrumentation can be useful. A solar power analyzer can also be a useful tool to ensure that an inverter and complete system is performing correctly and delivering the payback expected by a customer. Thermal imaging cameras can highlight inefficient modules or cells. IV curve tracers, which measure the voltage and current output performance of a module, are not a compulsory requirement during commissioning, but can be very useful for O&M by helping to ensure correct performance against manufacturers’ requirements and for various other forms of diagnostic testing.
To meet these various electrical test needs, some contractors have traditionally used multiple instruments that include an earth continuity and insulation resistance tester‚ a multimeter and DC clampmeter, along with various associated connectors and leads. However, the risk with such “homemade” kits is that not all of the tests required by original system commissioning and installation standards will be covered and, with different PV system electrical tests potentially requiring the use of different testers, using such an array of instruments can be cumbersome and time consuming.
This sort of consideration has led to the introduction of a new generation of dedicated multi-function solar PV electrical testers that are capable of carrying out all electrical tests required by international standards, such as IEC 62446, on grid-connected PV systems.
With the push of a single button, combination testers automatically carry out the required sequence of electrical tests in a safe and controlled manner. Testing can be conducted quickly and easily with the tester being pre-programmed to run an automatic sequence of required tests and using specially designed PV test leads which quickly connect and disconnect from the installation circuit.
For a comprehensive approach, alongside electrical testing, an irradiance meter is also required to measure how much solar power is available at any particular location. The most accurate solar readings are provided by irradiance meters which utilize sensors which are similar to the technology utilized in the panels themselves and the ideal solution is to utilize an irradiance meter which uses a photovoltaic cell as its sensor rather than a pin diode.
With some instruments, special wireless “Solarlink” connectivity between the multi-function tester and an irradiance meters enables real-time irradiance to be displayed and measured at the same time as electrical testing is being undertaken.
This means that irradiance, module and ambient temperature can be recorded in real time within the test instrument as the electrical tests are conducted. Once testing is completed, the USB download of time and date stamped test results, with irradiance and temperature measurements, provide full traceability and speeds up the completion of PV system reports and customer documentation.
In the latest generation solar PV combination testers, the multi-electrical test capability has been linked with I-V curve tracing assessments. In this new test concept, alongside electrical tests, the Seaward solar PV210 produces I-V curve analysis on modules of strings in accordance with IEC 61829 to determine if the measured curve deviates from the expected profile and highlighting the need for any further analysis or fault finding. The fill factor of PV systems is also assessed.
For full detailed analysis, measured data can be transferred instantly from the test instrument to an accompanying PVMobile Android App using wireless NFC connectivity to create high definition color displays of the I-V and power curves for individual PV modules or strings. The accurate visual comparison of curve shapes can be used for the immediate identification of common problems such as shading, defective cells or poor electrical connections.
To address remote monitoring issues and the maintenance of control records, the new test technology can send test data and I-V curve comparisons directly from the test site using the PVMobile app, to enable data to be made quickly available anywhere, for maintenance records or further analysis and investigation.
Innovation in solar PV test technology is playing its part in improving O&M productivity and effectiveness and helping PV operators of all sizes to ensure that their investments are properly managed and that their energy generation is maximized.
from Solar Power World http://ift.tt/2b111mU
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