Glossary Category 6: Construction & Operations
Key terms used during the building, commissioning, and operational phases of U.S. renewable energy projects.
Notice to Proceed (NTP)
Definition: A formal authorization to a contractor to begin construction activities on a project.
Example: After securing all permits and financing, a solar developer issues NTP to the EPC firm to mobilize crews and equipment on-site.
Note: Often a milestone for payment schedules and loan draws.
Engineering, Procurement, and Construction (EPC) Contract
Definition: A turnkey agreement where a single contractor is responsible for designing, sourcing, and building the entire project.
Example: A battery storage developer signs a fixed-price EPC contract with a national firm to deliver a fully installed and tested 100 MW BESS.
Benefit: Streamlines project delivery and risk by placing responsibility on one party.
Balance of Plant (BOP)
Definition: All components and systems of a power plant except the generating equipment itself—typically includes foundations, wiring, access roads, fencing, etc.
Example: For a wind farm, the turbines are supplied by the OEM, while the BOP contractor handles roads, crane pads, electrical cabling, and substation construction.
In solar: BOP may include pile driving, trenching, inverters, and SCADA systems.
Substantial Completion
Definition: The point at which construction is sufficiently complete for the project to begin operation, even if minor punch-list items remain.
Example: A utility-scale solar farm achieves substantial completion and begins delivering power under its PPA while crews finish fence painting and signage.
Often triggers: Final payment, transition to operations, and warranty periods.
Commissioning
Definition: A structured process of testing and verifying that all systems perform as designed and safely integrate with the grid.
Example: A wind project undergoes a multi-week commissioning period that includes turbine startup, grid synchronization, and SCADA testing.
Includes: Functional tests, performance tests, utility sign-offs, and interconnection validation.
Commercial Operation Date (COD)
Definition: The date when a project begins full, contractual operation and starts earning revenue under a PPA or interconnection agreement.
Example: A 75 MW solar facility reaches COD on June 1, meaning it can now sell energy and RECs under its 20-year contract.
Key: Often used as a milestone for financing, tax credit eligibility, and operations handoff.
Operations & Maintenance (O&M)
Definition: The ongoing work to monitor, maintain, and optimize a renewable facility after construction is complete.
Example: A third-party O&M firm performs monthly site inspections, inverter checks, vegetation control, and energy production reporting for a solar farm.
Common: Many developers outsource O&M to specialized firms with 24/7 monitoring centers.
Availability Factor
Definition: The percentage of time a renewable energy system is operational and available to produce energy (excluding scheduled maintenance).
Example: A solar farm reports 99% availability over a quarter, meaning it was capable of operating nearly the entire time.
Distinction: Not the same as capacity factor, which includes production vs. theoretical max output.
Capacity Factor
Definition: The ratio of actual electricity generated over a period to the maximum possible output if the plant ran at full capacity 24/7.
Example: A 100 MW wind farm with a 35% capacity factor produces about 306,600 MWh per year (100 MW × 8,760 hours × 35%).
Note: Influenced by weather, curtailment, and technology efficiency.
Performance Ratio (Solar-Specific)
Definition: A measure of solar system efficiency that compares actual output to theoretical output based on irradiance, factoring in system losses.
Example: A utility-scale PV system has a performance ratio of 82%, meaning it converts 82% of available solar energy into usable electricity after accounting for shading, temperature, wiring losses, etc.
Used to benchmark quality and spot underperformance.
SCADA System (Supervisory Control and Data Acquisition)
Definition: A control system used to monitor and manage performance of renewable assets remotely, often in real-time.
Example: Operators use a SCADA dashboard to view inverter output, battery temperature, weather data, and alarms from a central control room.
Importance: Enables predictive maintenance and fast response to faults.
Preventive Maintenance
Definition: Scheduled inspections and servicing to reduce the risk of failures and extend equipment life.
Example: A solar site performs annual thermographic inspections of electrical connections and quarterly panel washing in dusty environments.
Routine: Tasks may include vegetation clearing, lubrication, and equipment cleaning.
Corrective Maintenance
Definition: Unscheduled repairs or replacements performed after an issue is detected.
Example: A wind turbine is taken offline after SCADA reports abnormal vibration, requiring gearbox repair.
Impact: Can affect availability and trigger penalty clauses in PPAs or insurance claims.
Repowering
Definition: The process of upgrading or replacing aging components of a renewable project to extend its life or improve performance.
Example: A 15-year-old wind farm replaces older turbines with higher-capacity models, increasing output without needing new land.
Incentives: Some repowering projects may requalify for tax credits if significant investment is made.
Vegetation Management
Definition: Ongoing control of plant growth at renewable sites to prevent shading (for solar), fire risk, or access obstruction.
Example: A solar developer implements a pollinator-friendly groundcover program to control vegetation without constant mowing.
Agencies: May be subject to local fire codes, environmental permits, or lease agreements.
As-Built Drawings
Definition: Final project drawings reflecting all changes made during construction, documenting the exact layout of infrastructure.
Example: After installing underground conduit differently than planned, the EPC updates the as-builts for future maintenance reference.
Required For: Final closeout, O&M handover, and sometimes permitting agencies.
Warranty Period
Definition: The time during which the EPC or equipment manufacturer guarantees their product or workmanship, typically ranging from 2–10 years.
Example: A solar inverter comes with a 10-year performance warranty; the EPC offers a 2-year workmanship warranty post-COD.
Claim Process: May include service response times, exclusions, and conditions for coverage.