EPC – To Last a Lifetime – Anil Jain, Managing Director, Refex Energy - India Renewable Energy Consulting

Excerpt of a presentation from the EAI Solar PV Developer – EPC Meet, Chennai, Jan 22, 2013

During the Developer & EPC meet Mr. Anil Jain, Managing Director of Refex Energy, made a presentation on EPC – To Last a Lifetime. He discussed factors such as AC and DC system design, tests to be conducted before commissioning the plant, and O&M practices.

Mr. Anil Jain began his presentation by introducing his company, mentioning that as a developer-turned-EPC they were in a very good position to understand the needs of a developer and how an EPC could meet them. He spoke of some of the basic points to be considered in ensuring the plant lasts for 25 years

EPC
- In-house design capabilities – To optimise the plant for site conditions
- Capability to deliver onsite – The execution team should be able to implement the plan and design
- Components – Choice of best quality components is essential to reliability
- O&M – A good service provider is required to ensure proper and timely maintenance is performed
- Design – The solar plant is designed as a series of compromises to provide the lowest levelised cost of electricity. Two vital components are
  - Modules – Attributes to be considered include cost, power output, benefits/drawbacks of technology type, quality, spectral response, performance in low light, nominal power tolerance levels, degradation rate, and warranty terms
  - Inverters – Important factors are compatibility with module technology, compliance with grid code and other applicable regulations, inverter-based layout, reliability, system availability, serviceability, modularity, telemetry requirements, inverter locations, quality, and cost

The electrical design of the plant comprises

DC system
- PV modules
- Inverters
- DC cabling (module, string and main cable)
- DC connectors (plugs and sockets)
- Junction boxes/combiners/disconnects/switches
- Protection devices
- Earthing
- AC system
  - AC cabling
  - Switchgear
  - Transformers
  - Substation
  - Earthing and surge protection

Other important factors are

Data acquisition and monitoring – The yield of the plant is monitored and compared with estimates from irradiation data to identify shortfalls and rectify defects. Also, this helps the power plants provide the required 24-hour forecasts at 30-minute intervals to the network operators
Construction – Quality of construction is important in raising finance for the project, particularly from international lenders. Some of the issues faced during construction are
- Foundations not being suited to ground conditions
- Discovery of hazardous/contaminated substances during excavation
- Incorrect orientation of modules
- Insufficient cross-bracing on mounting structures
- Incorrect use of torque wrenches
- Damaging cables during construction/installation
- Delayed grid connection
- Access/construction constrained by weather
- Insufficient clearance between rows for vehicle access
- Commissioning – Commissioning of the plant should prove that the plant is safe, robust, and performs to expectations. There are 3 kind of tests to ensure this
  - Visual acceptance tests – Detailed visual inspection of all significant aspects of the plant
  - Pre-connection acceptance tests – These are tests conducted before grid connection and include an open circuit voltage test and short circuit current test
  - Post-connection acceptance test – After connecting to the grid, a DC current test should be carried out to check that the promised performance ratio met. An availability test, usually over a period of 5 days, should also be carried out
  - Operations & Maintenance – This consists of
    - Scheduled maintenance
      - Module cleaning
      - Checking module connection integrity
      - Checking junction/string combiner boxes
      - Thermographic detection of faults
      - Inverter servicing
      - Inspecting mechanical integrity of mounting structures
      - Vegetation control
      - Routine balance of plant servicing/inspection
Unscheduled maintenance
- Tightening cable connections that have loosened
- Replacing blown fuses
- Repairing lightning damage
- Repairing equipment damaged by intruders or during module cleaning
- Rectifying supervisory control and data acquisition (SCADA) faults