avisolar's roof top OMS Hubs

Avi Solar’s Rooftop OMS Hubs

Continuously growing & geographically well spread out rooftop solar projects in India is in need of a quick and professional OMS services at its doorstep.

Understanding this need and leveraging its expertise and experience of handling O&M services for more than 700MW solar power plants across India, Avi Solar Energy has created its O&M hubs at different strategical locations with complete O&M resources to provide quick and professional O&M services for rooftop solar projects.

Avi solar Energy is geared up to fully to provide professional O&M services for rooftop projects in its already existing and also in its upcoming rooftop O&M hubs as depicted below.

avisolar's roof top OMS Hubs

For more details and enquiries, please feel free to contact us as

Email: sales@avisolar.com

Website: www.avisolar.com

 

SOLAR ROOFTOPS – O&M Challenges

SOLAR ROOFTOPS – O&M Challenges

 

Indian Government has set an ambitious target to install 100 GW of solar capacity by 2022, out of which 40 GW has to come from rooftop projects. However, the country has managed to set up just over 2 GW of solar rooftop capacity so far, while the target for the financial year 2017-18 was 5 GW, according to the data from MNRE.
Experts are raising concerns that Rooftop projects can’t be added in that quantity as a lot of roof structures especially residential are not designed to carry the additional loads of Solar PV Panels. However Small businesses, which contribute about a one third to India’s $2 trillion economy, suffer from high power tariffs and erratic supply causing them to fall back on expensive and polluting diesel generators to keep the lights on. This is where we see a potential for PV rooftop projects. Government establishments and commercial buildings like malls or even warehouses have the capacity to install significant capacities of Solar PV.

SOLAR ROOFTOPS – O&M Challenges

Once installed on roofs, It will be imperative for all players in the Solar Energy domain to come up with a suitable strategy to optimize power generation as well as tune-in operational efficiency.  Maintenance at regular intervals is crucial for extending the life and generation performance of solar plants of any size.

Avi Solar one of the leading O&M Service Provider for utility PV plants is now gearing up to serve the rooftop market in India. Unlike utility plant, it is not viable to have dedicated engineers for rooftops; hence Avi solar has created “O&M Service Hubs” at strategic locations across the country. These hubs will have a workforce and spares that will cater to a bunch of rooftops.

 

Few challenges specific to operation & maintenance of Rooftops are listed below:

Work Permit:  Most industrial rooftops have a permit system to work akin to a factory set up and O&M provider has to plan well in advance for any maintenance activity.

Planned schedules: Plant maintenance is a repeated activity with standard operating procedures to be followed for Preventive Maintenance (PM) and Corrective/ Break down maintenance (CM).

Reporting: Every scale of developer/Investor/Corporate owner of a solar PV Installation is interested in timely reports of Power generation and Health parameters of the Plant. The fairly recent advances in monitoring solutions have not penetrated the rooftop market. Reporting and analytics are not organized as much as Ground mounted plants.

Scattered sites: Ground Mounted plants may have a full-fledged SCADA monitoring system whereas many Industrial rooftop plants have to invest in third-party software (portals) to collate data from various sites.

Safety: As the Rooftop plants are at elevated places, the safety of workers is of paramount concern. Safe working practices and PPEs are a must in this industry.

 

SOLAR ROOFTOPS – O&M Challenges

 

Practical approach to O&M issues:

Based on extensive field operations experience and feedback from customers, Avi Solar O&M team has devised indigenous ways to address the above issues.  Micro-level operation management, Spare management, Optimization of resources based on requirements in each city and state is devised. Macro-level planning, safety training, and monitoring ensures the smooth functioning of the business.

Technical solution from Professionals in the field:

Avi Solar Energy Private Limited has developed a software tool SPIDAR (Solar Plant Intelligent Data Acquisition and Reporting), a simple application software that connects owner/client of a PV plant with the real-time generation reports and performance data gathered by engineers/technicians at the site.

Snail Trails on Solar Panels – an aesthetic issue or a performance limiter?

Snail Trails on Solar Panels– an aesthetic issue or a performance limiter?

As Solar Plants age, Developers must reckon many problems. Modules do degrade over time and may underperform. Microcracks may develop as modules are exposed to the elements all through their life time. Some modules may inherently have had micro cracks from the time it was shipped and can extend over larger cross-sections during operations. Over & above thermal cycling can affect metal contacts, solder interconnections & causes thermal stresses in the module. This can have serious consequences and may result in catastrophic failure in the long term.

Since 2012 a phenomenon has been observed across many Solar plants, of small dark brownish lines or partial discoloration being caused on PV modules. These were termed “snail trails” and research started on its occurrence and the impact it can have on power generation.

After studying patterns across many plants, it was broadly concluded that mere existence of snail trails by itself does not affect power generation. However, snail trails seen where micro cracks run across cells may affect power generation. Even this must be assessed to be sure.

What are snail Trails: 

Snail trails are discolouration of the panel, which usually builds up over couple of years of power production on the field. Moisture can enter through the back sheet and diffuse to the cell surface. Here the silver from the grid contact fingers may get dissolved and the silver ion migration to the EVA (Ethyl Vinyl Acetate) foil encapsulation can set in the snail trail formation – mainly Silver nanoparticles showing a typical brownish colour.

It has been ascertained that this discolouration happens due to the formation of silver acetate, that is synthesized by silver carbonate (Ag2CO3) originating from the reaction of Ag ions and carbon dioxide and acetic acid that originates from the degradation of the EVA encapsulation. The effect of this reaction is that it can reach the front of the panel from the back and causes a chemical breakdown on the front of the panel of the grid fingers. This becomes visible as snail trails and was possibly thought to bring in a reduction in the panel’s performance as it can cut irradiance if these trails run across the cell. Though it is not true it is surely an indicator for cracks within the cells. The snail trails are almost always located at cell edges or along micro cracks that can run across the cells in the panel and these are ones that can possibly lower power production. So, it is more of chance that the cracks are deep enough that may result in more stresses building up and thereby a deterioration in performance by creating potential hot spots.

In view of the perception that snail trail affected modules can have adverse impact on generation, Developers are a worried lot that the solar plant should not affect their Return on Investment (RoI) and reduce the life of the modules.

 

It is better to ascertain the impact by conducting tests on samples of snail trail affected modules. 

Various tests are possible such as

  • Thermal Imaging
  • Electroluminescence
  • I-V tests                        
  • Raman Spectroscopy.

Figure 1: Snail trail affected module

Figure 2: Thermal Imaging of Snail Trails on Module

To assess performance differences between snail trail affected and unaffected modules the string currents were measured during peak generation time. Data is shown for two sample sets.

No conclusion could be drawn about underperformance of snail trail affected modules.  Observation was that the values of current and voltage continued to be in the same range for both sets of modules

The technical team recommended that one of the best methods to assess the impact of Snail trail affected modules is to carry out Electroluminescence (EL) tests to gauge the structure and depth of the microcracks within the module from the EL images alongside I-V characteristics of the modules. Some samples were taken for EL tests/I-V tests. The Fill Factor (FF) of one of the modules recorded a drop of 6% against data sheet specifications. Considering the age of the plant to be 4 years, a 6% drop in FF in one of the modules translates to an annual average deterioration of 1.5%, slightly above usual thresholds of degradation. This could possibly relate to the microcracks in the snail trail module affecting performance. The values of the Series resistance of the cell showed up higher for such affected cells than other unaffected modules.

Figure 3: EL image of Module with micro-cracks

A clear picture will emerge after performing Electroluminescence tests and I-V characteristics tests. The intensity of the cracks, if any, can easily be seen and the Fill Factor data from the I-V tests will be an indicator of any performance dip or quality problems in the module. If the results match the manufacturer specifications or indicate minor problems, then it can be concluded that the performance aspects are intact, otherwise these affected modules are the ones to observe for deterioration in future.

 

Another way to understand the effects of snail trail affected modules is to analyze the monthly plant generation recorded during the previous year and compare it during the same month in the present year. If the generation difference is <0.8-1% a year later under non-break down conditions and normalized to insolation levels, it is well within limits of degradation – very usual of plants ageing and the performance ratios dipping year on year. Otherwise, it can be gathered that the module degradation has set in for the affected modules.

Challenges in Operations and Maintenance of a solar plant

 

Preventive Maintenance:

Preventive Maintenance includes routine inspection and servicing of all plant equipment. It is a necessary activity to prevent breakdowns and reduce energy yield losses. Following the Standard Operating Procedures (SOPs) and standard Checklists helps ensure consistency and quality of work.

Condition Monitoring:

Condition based Monitoring involves monitoring of equipment condition and plant operation on real time basis and addresses potential problem at a very early stage to prevent breakdown. A significant change in condition can be indicative of a likely fault that can occur.

Corrective Maintenance:

Corrective maintenance activities begin in the event of a fault.  The goal should be to clear the faults and restore operation of the equipment within the limits of contractual Plant availability.

O&M Budget:

Minimum budget within which to manage the smooth operations of a solar plant is one of the biggest challenges.

Here the site management strategy should be comprehensive for a better performance minimum cost along with customer satisfaction.

Documentation:

To maintain the record of each activity at the site and provide this information on time without any delay to the client. This is one of the best practice in O&M services.

Spare Management:

“Keeping Machines in fit condition calls for right spare parts at right time in right quantity”

Inventory management system is one of the best ways to track stock, warranty, and spares maintenance to ensure smooth operations in a plant.

Skilled Manpower:

Skills Training is most important for improving workmanship and a productive work environment.

Behavioral and Technical skills may be honed on the job so that the O&M provider helps

  • Maintain a healthy work environment and can enhance the quality of work
  • Minimize accidents on the job
  • Minimize breakdown time
  • Standardization in Plant and internal process

 

Plant Performance:

To achieve the plant performance in terms of Performance Ratio (PR) and Operational Performance Ratio(OPR), Generation units, reduce Breakdown and ensure smooth operation, following tasks are important for the on-site team:

(1) Module Cleaning as per desired frequency and site conditions

(2) Vegetation control as required

(3) Spares Management

(4) Manpower optimization

(5) Quality Maintenance work

(6) SCADA Monitoring

Safety:

When working at a Project site, it is in the interest of people and property to maintain the safety protocol and use (Personal Protective Equipment) PPE’s and the right methods during the work for protection from any kind of hazards.