PV Solar Development Process EPCO

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By Jeff MacKinnon, P.Eng., PE

I started to write the entire PV Solar Development process in a single article and it started to get too long for the internet. In the first paragraph I even mention that each phase could be a book and this would be a summary, but I still wasn't able to summarize it enough.

If you attended the presentation I did with Net Zero Atlantic in September, this is a section that I only dedicated a single slide, and this is the part where I expand on it.

If you haven't seen the first part describing the development process, you can find it here that jumps right into the first stage of a PV Solar Development project. For everyone else, lets get into the engineer, procure, construct, operate (EPCO) stage of the PV Solar Development process.

EPCO Stage

The EPCO stage is the execution stage, it will include the following phases:

  1. Detailed Design and Permitting
  2. Procurement and Construction
  3. Testing and Acceptance
  4. Operations

Detailed Design

Detailed design starts when the project scope and business model is sufficiently complete that the:

  • interface to the utility,
  • high level one-line,
  • real estate, and
  • over all project requirements are written down and likely aren't going to change in a material manner.

This is an important decision gate and if one of these items change, then the ripple affect will result in a lot of re-work.

The detailed design process will follow a framework similar to the one I outlined a few weeks ago, but the specifics will be different for every project execution type, and where you are as part of the project team.

For any project that has a mix of commodity and custom equipment, I suggest developing the design first to develop the requirements for major pieces of equipment, then the interface for this equipment.

For example, if the project is using large central inverters vs smaller string inverters, develop the specifications and requirements for these so that they can be sent for final selection and procurement before starting the detailed LV string design.

Some other major pieces of equipment that should be prioritized include:

  • Medium Voltage switchgear
  • Generator Step-up (GSU) transformer [1]
  • Utility SCADA and P&C cabinet [2]

The final part of the detailed design stage is procurement.

Buying Early

My suggestion today, is similar to that almost two years ago, research possible lead time critical paths early and make decision required to keep the project on track.

This is especially true for high-voltage equipment and power transformers. The lead times that I have been quoted at the time this is published is up to 54weeks for a 10MVA power transformer and longer for 69kV gang-operated switches.

The supply chain is a mess, and with the recent election in the USA, I expect that it will be even more chaotic over the next few years.

Permitting

Like all projects there are a varity of permits that will need to be obtained before starting the construction phase. To ensure that the project continues to be feasible these some of these permits should be in hand during the FEED stage of the project.

In a lot of cases there will be permits that will be required to obtain other permits. To ensure that the permitting process doesn't affect the project timeline, I suggest that you develop a detailed permitting plan early in the project developing process.

Include all the inter-dependencies that these permits have and assign project team members as "owners" for the various permits and agreements.

Some of the permits that will be required for all projects include: [3]

  • Land Use Permit
  • Environmental Permit
  • Grading Permit
  • Engineering Design Permits (structural, civil, building, MEP, etc)
  • Drainage Design Permit
  • etc

Procurement and Construction

Depending on the project structure, and if there have been any pre-purchased equipment, like some of the long lead items mentioned above, the procurement & construction process will be different in the details.

In general the procurement and construction process will start with the selection of the EPC and then the execution of the project execution plan (PEP).

Part of the scope for the EPC is the development of the Testing, Commissioning, and Acceptance program. This program is approved during the construction process, but development should be started during the detailed design.

It is this program that is executed int he next project phase.

Testing and Acceptance

There are generally various levels of testing and acceptance during the project construction and commissioning process.

There are 5 levels of testing and acceptance during the commissioning process.

Level 1

Level 1 includes the acceptance of equipment at the factory, before being delivered to site.

This includes factory acceptance tests (FAT) during the procurement of major equipment. The FAT should be witnessed by the owners representative and have a written report to be accepted. This ensures that the equipment is as designed when its leaving the factory.

For commodity material and equipment a shop drawing review and acceptance is all that's required.

Level 2

Level 2 includes the quality monitoring during construction. This includes inspecting laydown and storage areas to ensure that the equipment is protected, auditing material acceptance reports to ensure that the material that has been paid for is on site in a as-new condition, etc.

Level 3

As the equipment is installed it will be tested to ensure that it hasn't been damaged and operates as per the detailed design.

Some of these tests include:

  • Calibration tests for measuring equipment
  • MV/HV cable tests
  • LV Cable meggar and continuity testing
  • etc

Level 4

Level 4 is the start of functional testing. This can start when specific areas have substantial completion of the construction process.

These tests are called start-up and Site Acceptance Tests. All parts of the system should be tested with load to ensure that they operate during normal and abnormal [4] conditions.

These tests will include the following systems, at a minimum:

  • inverters,
  • protection & control (P&C),
  • site SCADA and Energy Management System (EMS),
  • UPS,
  • building services, if required (security, HVAC, etc),
  • Grid interface

Level 5

Level 5 acceptance is operating the plant during various time periods without interruption. For example the time periods for acceptance could include:

  • 24h
  • 72h
  • 10d
  • 30d

In my experience that first one, the 24h test, is the hardest to reach, after that the majority of the bugs have been worked out of the system and it will be mostly smooth sailing.

The next hardest is the 30d. During the first 30d most of the normal-abnormal system operations will have happened.

After the last time period acceptance the system is ready to be handed over to operations.

Operations and Maintenance

It is common that the EPC will have a contract to operate the facility for 1-3years, and then transitioning to the owner after that period, or a contract term being extended for 3-5 years on a renewable basis.

During this phase of the project the site is operated based on a O&M plan for the project. This plan will include (at a minimum) the following:

  • Organization chart,
  • Preventative Maintenance Schedule,
  • Maintenance Task frequency,
  • Spare parts management,
  • PV cleaning method and schedule,
  • Training program and schedule,
  • Performance monitoring and optimization,

Closing

These first 4 parts outline the process of executing a utility scale PV solar project.

Continuing this series I will be getting into the details of different parts of the solar project from: - off-grid vs on-grid, - defining the project (maximizing energy, grid services, exportable energy, etc) - discussion on central vs string inverters for utility scale projects - etc.

I don't have a schedule for developing these, but if there is something specific that you would like me to cover, contact me.

If you like what you have been reading and want more, I have a newsletter than I write on these topics and others.

Footnotes
[1]This is the power transformer that will transform the voltage to that of the point of common coupling/point of interconnection.
[2]This is a negotiation that for some utilities and regulators may take a longer time than would seem necessary. This is especially true for utilities that are integrated and traditionally include generation, transmission and distribution. They don't work with independent power producers (IPP) and may request requirements that will drive the detailed design process.
[3]This list is VERY far from all inclusive. I strongly recommend working with a local team to determine all the permits and agreements needed for the project.
[4]I'm not sure why, but the abnormal part seems to be missed on a lot of smaller projects. When I'm reviewing FAT and SAT test plans I always look at them with the eye of how can we induce abnormal conditions to ensure that the equipment will operate in a predictable manner. It is critical that the system can transition from an unknown/abnormal state to a known/normal state without damage (or limited damage) to the system.
[*]Featured image by Jonathan Cutrer