Chapter 6. Renewables – Solar and Wind

Introduction

Renewable energy sources like wind and solar are increasingly positioned to meet the needs of new large electrical loads. These technologies offer scalable, clean, and cost-effective power generation that can be deployed near load centers or integrated into the grid. Wind and solar systems can be rapidly developed compared to traditional fossil fuel plants, and when paired with energy storage or flexible grid management, they provide reliable and resilient power. Their modular nature allows for tailored solutions that align with the energy demands of new facilities, while also supporting sustainability goals and reducing dependence on carbon-intensive generation.

Solar photovoltaic (PV) systems convert sunlight directly into electricity through the photovoltaic effect. Semiconductor materials—most commonly crystalline silicon (c-Si)—generate direct current (DC) when exposed to sunlight. These cells are interconnected into modules, which are assembled into large arrays. Inverters convert the DC output to alternating current (AC) for grid compatibility. [1] Utility-scale PV systems also incorporate DC and AC combiner boxes, transformers, and monitoring infrastructure. Modern modules typically last 30–35 years, with c-Si technologies accounting for more than 80% of U.S. installations. [2] [3] The modular design and fast construction timelines make solar PV especially suited to large load applications and grid diversification.

Solar PV is a fully mature, mainstream technology with 1.6  TW of cumulative global capacity by the end of 2023, and annual additions surpassed 400 GW in 2023. Dominated by crystalline silicon modules (96% of shipments in 2023), utility-scale systems exhibit low degradation (<0.5%/year), long lifespans (30–35 years), and generation costs below new coal or gas plants. [4] Recent advancements in solar technology include improvements in panel efficiency, the widespread adoption of bifacial modules, and the integration of smart tracking systems and energy storage, all of which enhance performance and grid reliability.

The rapid rise in solar PV as a significant source of power has taken many by surprise.  Solar PV was less than 1% of energy produced in the US in 2015 and then rose to 4% in 10 years.  Nevada has the highest share of solar power at 23%; California follows at 19%; with Texas, Florida, North Carolina and Arizona also generating significant amounts of solar electricity.  Between 2025 and 2030, Texas, in spite of its oil & gas resources, is projected to double its installed solar capacity, underscoring the scalability and rapid deployment potential of PV systems.

Wind power generates electricity by harnessing the kinetic energy of moving air. As wind flows over turbine blades, aerodynamic lift causes the rotor to spin, driving a generator within the nacelle. Utility-scale systems typically employ horizontal-axis wind turbines (HAWTs), mounted on towers often exceeding 260 feet in height to access stronger and more stable winds. [5] Wind energy projects can scale by increasing the number of turbines or by deploying larger turbines with higher capacities. Modern onshore turbines average around 3.4 MW, with some exceeding 5 MW. [6] The scalability of wind projects is influenced by factors such as land availability, grid infrastructure, and wind resource assessments. Technological advancements have led to higher capacity factors for wind turbines, enabling more efficient energy extraction across various wind resource regimes. [7] This progress supports the development of larger wind farms capable of meeting substantial energy demands.

Globally, wind power capacity reached 1,174 GW in 2023, with the United States contributing 155 GW and wind accounting for 10.2% of national electricity generation. [8] [9] Texas leads the nation in installed wind capacity, producing over 40 GW and contributing more than 26% of the country’s wind-sourced electricity. In 2023, wind accounted for 28.6% of Texas’ electricity mix—second only to natural gas—with over 15,300 turbines spread across 239 projects. Texas now generates more electricity from wind than from coal or nuclear sources, underscoring its central role in the state’s energy portfolio. [10]

Wind Energy is a mature and proven technology with over 1.1 TW of global installed capacity as of 2024, including 151 GW in the United States. Utility-scale turbines ranging from 2MW to 6MW deliver consistent performance with capacity factors of 35-45%, supported by standardized designs and decades of operational experience. [11] In wind energy, larger turbines with taller towers and longer blades are increasing output, while offshore wind is expanding rapidly through the use of floating platforms and digital monitoring systems. Both technologies are expected to continue evolving through AI-driven optimization and greater hybrid integration with storage solutions.

1 Deployment Schedule

A large utility-scale solar PV farm on a transmission electrical network typically takes between 2 to 5 years from project conception to initial power generation, depending on permitting timelines, interconnection requirements, and equipment procurement. Smaller projects (<20 MW or <10 MW depending on local grid operator) designed for behind-the-meter or microgrid use on distribution electrical networks generally fall on shorter timelines, down to 1 year, due to reduced permitting and simplified grid interaction. [12]

The development timeline for onshore wind farms typically ranges from 3 to 6 years, accounting for site assessment, wind resource monitoring, environmental permitting, land acquisition, and transmission interconnection. While turbine installation itself may take only a few months, the permitting and planning phases can significantly extend project schedules—especially in regions with limited transmission capacity or wildlife protections. [13]

Permitting & Regulatory Approvals

For both solar and wind, the permitting process includes unique requirements not found in conventional energy projects. Wind developers must conduct detailed avian and bat habitat studies, noise assessments, and wildlife impact evaluations leading to longer environmental review phases. [14] Solar farms, as well as distributed systems like community‐scale microgrids, often require land use clearances, cultural/archeological site reviews, and comprehensive stormwater management permitting, particularly for large ground‐mounted installations. Both technology types need grid interconnection studies that account for variable output patterns, plus public hearings or local zoning variances when projects are near residential areas.

Permitting can meaningfully delay commercial‑scale renewable energy roll‑out. Environmental impact statements (EIS) under NEPA can stretch over 12–24 months, especially for projects on federal land or in ecologically sensitive zones. In states like Texas, onshore wind projects must coordinate with both the state Public Utility Commission and multiple county authorities, leading to overlapping jurisdictional reviews. Limited local staffing and backlog in agencies, such as Texas Parks & Wildlife and local historical commissions, can extend permit review by several months. Finally, interconnection queues can slow projects, especially in congested regions, adding unpredictable delay before actual construction permits can be granted.

Interconnection

Grid interconnection remains one of the most complex and time-consuming hurdles for utility-scale renewable energy projects. Projects reaching Commercial Operation Date (COD) in 2023 experienced average interconnection delays of over five years, up from roughly three years before 2010. [15] These delays are driven by increasingly congested transmission systems, complex queue management processes, and a lack of standardized technical review procedures across balancing authorities. While behind-the-meter or distributed solar systems can often bypass interconnection studies, utility-scale wind and solar projects—especially those paired with large industrial loads like 100 MW data centers—require extensive modeling, impact studies, and negotiations with transmission providers to ensure system reliability, stability, and compliance with regional planning requirements.

Renewables face specific interconnection delays due to the need for detailed power flow analysis and the variability of their output. Unlike dispatchable resources, wind and solar must demonstrate their ability to integrate without compromising local voltage or frequency standards. This often triggers additional grid upgrade requirements, which must be completed before a project can connect, adding years to the schedule. The interconnection queue process itself is often first-come, first-served, and many projects are delayed due to a backlog of speculative filings. [15] ERCOT, PJM, and other ISOs have recently begun reforming these queues to prioritize shovel-ready projects, but bottlenecks remain a major barrier to timely deployment.

Procurement

The global PV module supply chain is notably concentrated: five leading manufacturers—Tongwei, Jinko Solar, Longi, Trina Solar, and JA Solar—produced approximately half of global PV module output, with the top ten manufacturers accounting for around 564 GW dc collectively. According to a 2024 NREL report, roughly 83 % of components installed in U.S. PV systems originated outside the United States, exposing projects to risks from tariffs, trade policy shifts, especially concerning Southeast Asian producers, and international shipping delays and inflation. [4] These challenges drive up module costs, elevate logistical complexity, and introduce schedule uncertainty, particularly utility-scale systems that rely on global supply chains.

In the U.S. wind market, leading turbine suppliers include GE Vernova, Vestas, Nordex, Siemens Gamesa Renewable Energy, and Goldwind, with GE Vernova supplying approximately 58 % of installations in 2023. [16] Wind projects face unique logistical hurdles: oversized blades, nacelles, and turbine towers require specialized transport (e.g., heavy-haul trailers), complex permitting for oversized loads, and detailed road and site access planning. Delays in transporting and coordinating these large components can significantly postpone site assembly and commissioning. These challenges have led manufacturers to favor offshore production facilities, with larger fabrication capabilities, potentially diminishing the competitiveness of U.S. domestic facilities.

Both solar and wind farms increasingly require medium- and high-voltage transformers (e.g., pad-mounted units, generation step-up transformers), and high-voltage circuit breakers. Lead times for these critical components have skyrocketed with transformer lead times rising from pre‑pandemic averages of 24–36 weeks to around 115–130 weeks (2–2.5 years), with large GSU units taking up to 120–210 weeks (3–4 years) to procure. These extended delays add years to project schedules and can become major obstacles to reaching Commercial Operation Date (COD) targets. Industry analysts warn that demand will likely outpace capacity ramp-up through at least 2026, especially for transmission-scale transformers. [17]

Securing land for wind or solar development is often a lengthy, multi-year endeavor that involves complex negotiations with numerous individual landowners. Over time, many properties have been fragmented through inheritance, making it difficult to assemble large, contiguous tracts suitable for utility-scale projects. One of the quickest—though more costly—routes to land control is through real estate developers who already represent landowners and have pre-negotiated agreements in place, significantly accelerating the acquisition process. Renewable energy leases typically follow one of two structures: the first combines a modest annual payment, often around $10 per acre, with a royalty of 2% to 4% of gross energy sales; the second offers a flat annual lease rate, generally about 8 to 10% of the land’s assessed value, without any royalty. These agreements commonly span 25 to 50 years, providing long-term stability for both developers and landowners.

Construction & Start Up

Utility-scale solar farms require significant planning, permitting, and interconnection studies prior to construction, particularly when located on large tracts of rural land. Once permits are secured, construction begins with site grading, access road installation, and trenching for electrical conduits. Mounting systems are installed in phases, followed by the placement of thousands of photovoltaic (PV) modules. Inverter stations, medium-voltage transformers, and collector substations are installed in parallel with panel deployment. Due to the scale and geographic footprint, site logistics, workforce coordination, and weather delays can significantly affect construction timelines. Final commissioning includes performance testing, grid synchronization, and inverter calibration, with oversight from utilities or independent engineers. For solar projects over 100 MW, total construction and startup may take 12 to 18 months, depending on site conditions, permitting delays, and supply chain constraints.

Wind farm development begins with extensive site selection, wind resource assessment, and permitting before construction can begin. Once approved, construction includes grading access roads, laying underground cables, installing concrete turbine foundations, erecting towers, and finally mounting nacelles and blades using cranes. Each turbine may require multiple oversized transport loads, specialized crews, and up to 500 cubic yards of concrete for the foundation depending on soil conditions. Installation of electrical collection systems, substations, and grid interconnection infrastructure follows. Startup involves commissioning each turbine, synchronizing with the grid, and conducting performance testing under various wind conditions. From groundbreaking to full operation, wind farms typically require 6 to 12 months depending on scale and weather delays. [18]

2 Operational Capabilities

Dispatchability and Flexibility

Wind and solar generation offer significant downward operational flexibility, with the ability to rapidly curtail output from full capacity to zero. Unlike conventional fuel-based generators, however, they lack controllable modulation and instead rely on curtailment mechanisms—typically initiated by grid operator commands or inverter-based controls—to manage output. Solar photovoltaic systems can quickly reduce power via inverter curtailment but are inherently limited by the instantaneous availability of sunlight. Similarly, wind turbines can be curtailed through control systems or blade pitching, yet remain constrained by prevailing wind conditions. While both technologies provide full turndown capability from 100% to 0%, their upward flexibility is entirely dependent on environmental resources, making them non-dispatchable in the traditional sense. This one-sided flexibility contributes to grid balancing but requires precise forecasting and complementary solutions such as energy storage to ensure responsiveness to load changes.

Start Times and Ramp Rates

Utility-scale solar and wind systems both have relatively fast start times compared to conventional thermal generators:

• Solar PV systems can reach full output within seconds to a few minutes after sunrise or cloud clearing. Since they have no moving parts and don’t require warm-up, their ramp-up is nearly instantaneous, limited mainly by inverter controls and irradiance levels.
• Wind turbines take slightly longer due to mechanical components, but still start relatively quickly—typically within 1 to 2 minutes from a stop, and 15 minutes to full power depending on wind availability and turbine design. Cold weather or maintenance states may add delays, but modern turbines are designed for automated, fast restarts when conditions allow. [19]

In both cases, while they can ramp up quickly when conditions are favorable, their start is resource-dependent, meaning they can’t initiate generation on demand like dispatchable sources.

Solar photovoltaic systems are capable of rapid power changes, and sudden irradiance shifts like cloud transients have the potential to ramp up to 50% of rated capacity per minute.  To maintain grid stability during rapid weather caused changes, many utility and grid codes impose up and down ramp rate limits—typically 10% of rated capacity per minute. Inverter controls and optional storage systems are commonly used to smooth these fluctuations and prevent voltage or frequency disturbances, especially in regions with high solar penetration. [20]

Wind turbines exhibit more moderate ramping behavior, utilities generally limit changes to 10% of rated power per minute although the equipment is capable of reacting faster. This is managed through active blade pitch control and generator torque adjustments, which regulate power output to protect both the turbine and the grid. Grid codes, such as those in Germany and Ireland, enforce similar ramp limits to ensure predictability and stability. Although individual turbines may ramp slowly, large wind farms benefit from geographic dispersion and staggered turbine behavior, which help smooth aggregate ramping across the system.

Grid Stability and Power Quality

Traditional power systems maintain frequency stability through the rotational inertia of synchronous generators, which act as a buffer during disturbances by resisting sudden changes in frequency. This inertia provides critical time for primary frequency controls to respond. In contrast, modern renewable energy systems—particularly solar PV and variable-speed wind turbines—interface with the grid using power electronics, which decouple their mechanical inertia from the grid. As a result, they contribute little to no physical inertia under normal operation, requiring new approaches—such as synthetic inertia—to help maintain frequency stability.

Solar photovoltaic (PV) systems, lacking rotating mass entirely, rely entirely on inverter-based control to deliver fast frequency response. While they cannot provide inertia in the traditional sense, PV inverters can simulate a similar effect by operating below maximum power output and using that reserved headroom to inject additional power during frequency dips. These systems can respond within milliseconds to a couple of seconds, with ramp rates exceeding 100% of rated output per second—much faster than conventional generators. The trade-off is an opportunity cost, as some generation must be curtailed during normal operation to preserve response capability. Nonetheless, grid operators in the U.S. (such as CAISO and ERCOT) have begun incorporating fast frequency response from solar in real-world applications. As solar deployment expands, its ability to deliver fast, precise power injection will play an increasingly important role in grid stability. [21]

Wind turbines can contribute to frequency support using synthetic inertia, though this support is inherently limited in duration. During a disturbance, wind turbines can briefly inject additional power—typically for about one second—by releasing kinetic energy stored in the rotating blades, slowing their rotor speed to help arrest a frequency drop. Once this burst of support is delivered, the turbine must recover its rotational speed, during which it cannot continue providing inertial support and may even temporarily reduce output. Unlike conventional generators that offer continuous inertial support, wind turbines provide a short, one-time response before requiring several seconds to reset. Still, their high ramp rate—up to 25% of rated power per second—allows them to react quickly, making synthetic inertia from wind effective for initial frequency arrest, especially when combined with curtailment-based frequency response or other fast-acting technologies. [21]

Synchronization and Control

Unlike synchronous generators, utility-scale solar PV systems interface with the grid through power electronics, specifically inverters, that convert DC to AC and ensure proper synchronization with grid voltage and frequency. Modern inverters include advanced phase-locked loop (PLL) algorithms that continuously monitor and match the phase angle of the grid. These systems can provide grid-forming or grid-following capabilities depending on the design. Although they lack mechanical inertia, many inverters now support virtual inertia through fast frequency response features, contributing to grid stability during disturbances.

Large wind turbines, especially those using doubly-fed induction generators (DFIG) or full-converter systems, synchronize to the grid using sophisticated power electronics. These systems decouple the generator’s rotational speed from the grid frequency, allowing variable-speed operation while maintaining a stable AC output. Like solar inverters, wind turbine converters can be configured as grid-following or grid-forming units, depending on the system architecture. Full-converter wind turbines (common in newer installations) offer more flexibility for voltage and frequency control, especially in weak-grid scenarios, and can support grid stability by contributing synthetic inertia and fast fault ride-through capabilities.

Parasitic Loads and Degradation

Parasitic losses in utility-scale solar farms are relatively low, typically ranging from 0.8% to 2% of gross generation. These losses come from internal systems such as inverter standby power, control electronics, trackers, and monitoring equipment. Tracking systems, where used, contribute an additional 0.2% to 0.4% annually. While parasitic consumption is minimal, environmental factors like soiling from dust, pollen, or pollution can result in energy losses of 3% to 5% or more, especially in arid or agricultural regions. These performance-related impacts highlight the importance of regular panel cleaning and site-specific maintenance strategies to ensure optimal energy yield. [22]

Utility-scale solar PV farms typically achieve a capacity factor between 20–25%, depending on panel efficiency, inverter performance, geographic location, and array orientation. However, solar performance degrades gradually over time. According to a 2022 analysis by the PV Fleet initiative, the national median degradation rate for PV systems is approximately 0.75% per year. This value varies with climate: systems in hotter regions degrade faster, at a rate of 0.88% per year, while those in cooler zones exhibit slower degradation around 0.48% per year. These losses accumulate, reducing total system output over time and should be considered in long-term generation planning and financial modeling. [23]

Parasitic and system-level losses in wind farms primarily arise from wake effects, electrical losses, and turbine performance deviations. Wake losses, caused by wind turbulence and reduced wind speed downstream of turbines, can account for 0% to 10% of total generation loss depending on site layout, wind patterns, and control strategies. Electrical losses—including energy lost in the collector system, substations, and transmission—typically range from 1.5% to 3%, driven by factors such as turbine spacing, cable length, transformer efficiency, and weather. Additionally, turbine performance losses of 1% to 3% can occur when actual site conditions differ from modeled operating assumptions, or when turbines are not optimally configured. While environmental factors like icing, soiling, or extreme weather can further reduce output, these are generally site-specific and are often managed with coatings, de-icing systems, or cleaning practices. Overall, wind farm design and control strategies play a critical role in minimizing parasitic losses and maximizing net delivered energy. [24]

Wind energy systems generally exhibit higher capacity factors, averaging 35% nationally, with newly constructed wind farms in 2022 achieving an average of 38.2%. Despite this strong performance, wind turbines also degrade over time. In the United States, wind turbines typically experience a performance degradation rate of 0.5% to 0.8% per year, based on long-term operational data. This gradual decline in energy output is primarily attributed to mechanical wear and environmental exposure. Contributing factors include blade erosion from rain, sand, or ice, bearing and gearbox fatigue, generator efficiency loss, and sensor calibration drift. Over time, increased turbulence loading, minor alignment shifts, and control system inaccuracies can further impact performance. While degradation is generally modest and linear, it accumulates over the life of a project—potentially reducing total annual energy production by 10–15% over a 20-year span. Proactive maintenance, real-time monitoring, and periodic component upgrades can help mitigate these effects and extend turbine performance. [23] [25]

3 Service Reliability

Availability and Failures

Wind and solar energy systems exhibit high operational availability, reflecting the percentage of time the systems are functional and capable of generating power when resource conditions allow. Modern wind turbines typically achieve around 97% availability, supported by improved design, remote monitoring, and predictive maintenance practices. [26] Solar photovoltaic (PV) systems generally perform even better, with typical availability reaching 98%, owing to their minimal mechanical complexity and low maintenance requirements. [27] While actual energy output is still constrained by the variability of wind and sunlight, these high availability rates demonstrate that, when environmental conditions permit, both technologies can reliably contribute to grid operations.

The leading causes of solar photovoltaic (PV) system failures, and resulting downtime, stems from equipment issues, particularly involving modules, inverters, and wiring. Module damage is a frequent culprit, often caused by hot spots, microcracks, water intrusion, or delamination, all of which can degrade performance or lead to complete failure. Inverters, which convert DC electricity from the panels into usable AC power, are another common point of failure. While micro-inverters and string inverters are typically replaced when they fail, large central inverters are usually repaired by swapping out components such as capacitors or printed circuit boards. These components are especially vulnerable and tend to fail within the inverter’s typical 10–15 year lifespan, meaning they are often replaced at least once during a solar system’s operational life. Wiring damage also contributes significantly to downtime, with issues like short circuits, open circuits, and ground faults often resulting from physical damage or environmental exposure. Together, these factors highlight the importance of proactive maintenance and quality component selection in ensuring long-term solar PV system reliability.

To better understand the reliability of utility-scale solar farms, it’s important to focus on the MTBF of individual components, as these values directly impact maintenance planning, system availability, and long-term performance. Component-level data shows that PV modules are extremely reliable, with an MTBF of approximately 28.6 million hours, while string connectors and string protectors exceed 15 million hours. DC combiner boxes have a lower MTBF of 318,000 hours, reflecting more frequent, though still manageable, failure rates. In contrast, the central inverter stands out as the most failure-prone component, with an MTBF of just 13,500 hours, making it a critical focus for redundancy and proactive maintenance strategies. [28]

Wind power systems rely on a range of complex components, each of which plays a critical role in maintaining reliable energy output, especially for large, continuous loads like data centers. Among these, the gearbox is one of the most failure-prone and costly components. It is responsible for increasing the rotor’s low speed rotation to the high-speed input required by the generator. Gearbox failures, particularly those involving bearings, which account for over 76% of such incidents according to the National Renewable Energy Laboratory (NREL), can lead to extended downtimes and repair costs ranging from $200,000 to $300,000. [29] Generators, while failing less frequently (1%–4% annually), also pose significant challenges when they do malfunction, often requiring full replacements or complex up-tower repairs that result in prolonged outages. [30] Wind turbine blades are another high-risk component, susceptible to material fatigue, lightning strikes, erosion, and cracking. [31] These failures are difficult and expensive to repair, often necessitating cranes and specialized crews, which can keep turbines offline for weeks. Electrical and control systems, including converters, are more prone to frequent failures due to environmental stressors like humidity and temperature swings. [32] Although these issues typically result in shorter downtimes, they still contribute significantly to overall system unreliability. The harsh operating conditions of wind turbines ranging from extreme temperatures to high torque loads and grid instability—further complicate maintenance and increase the importance of robust reliability planning. For critical-load facilities such as data centers, prioritizing high-risk components like gearboxes, generators, blades, and control systems in maintenance strategies and spare parts inventory is essential to minimize disruptions and ensure continuous power delivery. [33]

Wind turbines in the U.S. typically experienced a Mean Time Between Failures (MTBF) of around 7,000 hours, equivalent to approximately one failure per turbine per year. This data reflects an average across all subsystems and includes both minor and major faults. Most failures are attributed to electrical control systems, pitch mechanisms, and hydraulic components, while more serious issues like gearbox or bearing failures occur less frequently but result in longer downtimes. Continuous improvements in turbine design, monitoring systems, and predictive maintenance strategies are helping to extend MTBF and reduce unplanned outages across wind fleets. [34]

Solar and wind resource availability forecasting is the process of predicting the energy output from these variable renewable sources using weather and environmental data. Solar forecasts typically use inputs like cloud cover, solar irradiance, and temperature, with satellite imagery and weather models providing estimates from minutes ahead up to 7 days. Wind forecasting relies on wind speed, direction, and atmospheric conditions at turbine hub height, and can also provide forecasts from a few minutes to about 10 days in advance, though accuracy generally decreases with time. These forecasts are crucial for grid operators to manage variability, schedule generation resources efficiently, and maintain system reliability as renewable penetration increases.

Across the United States, solar irradiance levels vary significantly by region, but much of the country receives sufficient sunlight for viable solar energy generation (Figure 6.2). [35] According to the National Renewable Energy Laboratory (NREL), the annual average global horizontal irradiance (GHI) ranges from under 4.0 kWh/m²/day in parts of the Pacific Northwest and Northeast to over 6.0 kWh/m²/day in the desert Southwest including areas of Arizona, California, Nevada, New Mexico, and Texas. The highest irradiance values are concentrated in the Southwest, while large portions of the South, Midwest, and Southeast also exhibit strong solar potential in the 4.5–5.5 kWh/m²/day range, making solar a geographically versatile option for utility-scale and distributed applications nationwide.

The choice between fixed-tilt and single-axis tracking systems significantly influences the efficiency and energy yield of solar PV installations. Fixed-tilt systems are stationary and set at a fixed angle, typically optimized for the site's latitude. In contrast, single-axis tracking systems rotate along one axis, usually from east to west, to follow the sun's path throughout the day. This tracking capability allows for increased energy capture during morning and evening hours, leading to higher overall energy production. NREL data indicates that single-axis tracking systems can increase energy output by up to 25% compared to fixed-tilt systems, depending on the location and specific conditions. It is important to look for a location with high solar irradiance, minimal shading, suitable topography (flat/gently sloping land), soil stability, and close proximity to transmission lines (if connecting).

Developers of a PV farm also evaluate a site for wildlife, agriculture use, water resources, protected heritage/culture lands.  The site location will determine which rack mounts are able to withstand weather (winds/floods/snow, etc) and any agriculture usage.  Recently the dual use of land for solar power and agriculture (crops or livestock) has gained traction and is called "agrivoltaics", or "agrisolar", In this application, spacing of the PV modules and or the racking height might need to be adjusted for farming/livestock. [36]

Across the United States, wind energy availability varies significantly by region, but numerous areas exhibit strong, utility-scale potential (Figure 6.3) [37]. According to the National Renewable Energy Laboratory (NREL), the best onshore wind resources are concentrated in the central corridor of the country—including parts of Texas, Oklahoma, Kansas, Nebraska, South Dakota, and Wyoming—where annual average wind speeds at 100 meters above ground often exceed 7.0 m/s, with some regions surpassing 8.5 m/s. Coastal and mountainous regions, such as the Pacific Northwest and Appalachians, also demonstrate localized high-wind areas.

Wind turbines typically operate within an optimal wind speed range of 4 to 25 m/s (approximately 9 to 55 mph), making many parts of the U.S. viable for consistent generation. Seasonal and diurnal wind patterns also favor reliability: wind output tends to peak during spring and fall and often rises during nighttime hours, complementing solar generation, which is available only during the day. This temporal diversity supports grid balance when both wind and solar renewable sources are deployed together.

External Risks

While utility-scale wind and solar energy systems offer clean and increasingly cost-effective power, their reliability can be impacted by weather-related factors. These risks must be considered when planning generation for critical infrastructure or large loads.

Solar PV systems are generally considered reliable, with relatively few moving parts and low maintenance requirements. However, extreme weather events can temporarily disrupt performance. According to data from the PV Fleet initiative (2008–2022), the median outage duration after a major weather event was 2–4 days, resulting in only a 1% median loss in annual energy production. Long-duration outages of two weeks or more were extremely rare, observed in only 12 out of 6,400 systems. The most common vulnerabilities for PV systems include hail damage, inverter failures, snow accumulation, and wind uplift on poorly anchored racking systems.  Systems located in hotter climates may also experience higher degradation rates and heat-induced inverter derating, slightly reducing long-term reliability. [24]

In the solar PV farm infancy, hail has been the leading cause of solar farm damage, but it does not need to be.  While most solar panels are designed to withstand moderate hail, severe hail events—especially those involving stones larger than 1.75 inches (44 mm, or golf-ball size)—can cause cracking the glass surface and damaging solar cells.  This size hail occurs in "Hail Alley" which includes parts of Texas, Oklahoma, Kansas, Nebraska, Colorado, and Wyoming.  Solar arrays in this region should use solar panels with a thicker glass that is rated for larger hail; though the stronger solar panels are more expensive, they reduce the risk of greater financial loss due to hail damage.

Wind energy systems face a broader range of mechanical reliability challenges, particularly under extreme environmental conditions. Cold weather events can lead to ice accumulation on blades, reducing aerodynamic efficiency and increasing stress on drive systems. Turbines in cold climates are often equipped with blade heating elements or anti-icing coatings to mitigate this. However, mechanical failures in pitch control or hydraulic systems—particularly under thermal stress—can lead to significant downtime. Studies show that hydraulic system failures alone can account for up to 20% of wind turbine downtime, especially when exposed to fluid thickening in cold weather or thermal degradation in high heat.

Additionally, low-wind periods, such as those observed in early 2025, reduce capacity factors and can affect dispatchability if not paired with storage or supplemental generation. Conversely, extreme high-wind events can also pose a threat. While modern turbines are designed to withstand sustained winds of up to 112 mph and gusts of 156 mph, tornadoes or major hurricanes may exceed these thresholds, resulting in potential structural damage or catastrophic failure.

4 Environmental Sustainability

Emissions & Air Quality Impacts

Wind and solar energy systems produce no direct emissions during operation, offering a significant environmental advantage over fossil fuel-based generation. However, there are lifecycle emissions associated with the manufacturing, transportation, and installation of system components. For utility-scale solar PV, lifecycle greenhouse gas (GHG) emissions have been estimated at 10–36 g CO₂-equivalent per kWh, depending on panel type, location, and manufacturing practices. Most of these emissions are front-loaded, occurring during the production of silicon wafers, inverters, and mounting hardware.

Similarly, wind energy has one of the lowest lifecycle emissions profiles among generation technologies, estimated at approximately 11 g CO₂-equivalent per kWh. These emissions stem primarily from steel and concrete production for turbine towers and foundations, as well as blade and nacelle fabrication. Despite these embodied emissions, both wind and solar systems offer net emissions reductions over their operational lives by displacing fossil generation and avoiding associated SO₂, NOₓ, and CO₂ output.

Water Use

In addition, both technologies consume negligible water during operation, making them well-suited for deployment in arid or water-stressed regions, unlike thermal power plants that require substantial water for cooling processes.

End of Life & Recyclability

Solar panels typically last 25–30 years. Most of their materials, like glass, aluminum, and silicon, can be recycled, but U.S. recycling infrastructure is still limited. Valuable materials such as silver and copper are harder to recover cost-effectively. Only a few states, like California and Washington, have begun to set up recycling programs or EOL rules for solar systems.

Wind turbines have a similar lifespan of 20–30 years. Approximately 85% to 90% of a wind turbine’s mass—excluding the foundation, underground cabling, and other site infrastructure—consists of easily recyclable materials such as steel, aluminum, copper, and iron, primarily found in the tower and nacelle components. In contrast, about 6% to 14% of the turbine’s mass is made up of composite materials like blades, nacelle covers, and rotor housings, which currently pose greater challenges for recycling. [38]

Because the solar and wind industries are still relatively young, the volume of end-of-life materials remains limited, and the demand for recycling services has been modest. However, this is rapidly changing as installations age, prompting the emergence of new businesses focused on recycling components from solar and wind facilities.

Hazardous Materials and Waste Management

While wind and solar operate with significantly less hazardous materials and waste compared to fossil fuels or nuclear power, there are some items worth mentioning.

Wind farms use lubricants, hydraulic fluids, gearbox oil, coolants, and grease in turbine nacelles and gearboxes—all of which are hazardous materials that must be handled with care to avoid spills and environmental contamination. Storage and disposal must comply with EPA hazardous waste regulations, using labeled containers, secondary containment, and spill prevention protocols. Turbine decommissioning further introduces solid waste such as concrete foundations, scrap steel, and fiberglass composite blades. While composite blade recycling remains difficult, innovative methods like mechanical grinding, cement kiln co-processing, and thermochemical recycling are gaining traction. Additionally, turbines using permanent magnet generators include rare earth metals (neodymium, dysprosium, terbium), which are difficult to recover and raise sustainability and geopolitical concerns. A comprehensive waste and materials management plan is essential to proactively reduce environmental impacts across the project lifecycle.

Utility-scale solar farms primarily consist of materials like glass, aluminum, and silicon, which are generally non-hazardous. However, certain photovoltaic (PV) technologies may contain trace amounts of hazardous substances, such as lead, cadmium, or silver, particularly in cadmium telluride (CdTe) based modules (not-common). These substances may cause some modules to be classified as hazardous waste under RCRA, depending on toxicity test results. Additional materials, such as lithium-ion batteries, inverters, and switchgear, may introduce electronic waste or chemical residues during maintenance or component replacement.

Over time, decommissioned panels and equipment contribute to growing end-of-life waste volumes. The U.S. Department of Energy (DOE) estimates that solar panel waste in the U.S. could reach between 0.17 and 1 million tons by 2030, and up to 78 million tons globally by 2050. While up to 85% of PV module materials (such as glass and aluminum) are technically recyclable, actual recycling rates remain low—currently around 10%—largely due to economic and logistical constraints of the small volumes.  As volumes grow, recycling is expected to improve. Ongoing research is focused on improving recovery of high-value materials and increasing the efficiency of recycling processes. [2] Waste classification and management practices may vary based on panel type, condition, and local or federal regulatory frameworks.

5 Site Feasibility

Proximity to Energy Resources and Infrastructure

Choosing the right location is one of the most important steps in building a wind or solar farm. Both types of projects need to be placed where the natural resource is strong—for wind, that means steady wind speeds; for solar, plenty of sunlight. But just as important as the resource is being close to infrastructure, like transmission lines, substations, and access roads. If a project is too far from the grid, the cost and time needed to build new power lines can make it unfeasible. [39]

For wind farms, flat or gently rolling terrain with open space is ideal, and being near existing roads helps with transporting large components like blades and towers. Solar farms, on the other hand, are often built on cleared, flat land, like old agricultural or industrial sites, and need enough open space for thousands of panels. Both project types rely on grid connection points being nearby to keep interconnection costs low and timelines short. According to the Department of Energy, long waits for grid access and the need for new transmission lines are major reasons why some projects are delayed or canceled. [/16]

Modern planning tools now help developers map out potential sites by layering resource maps, land use data, and infrastructure networks. This makes it easier to find locations where the natural resource, infrastructure, and permitting environment all line up. Good siting reduces costs, shortens project timelines, and improves long-term performance.

Land Use & Power Density

Utility-scale solar farms require significant land area, with typical power densities of 3–7 acres per megawatt (MW) depending on panel efficiency, layout, and tracking systems. [40]  For example, a 500 MW solar farm requires 2500 acres of solar panels.  This is quite significant and pushes large solar farms into rural areas.  Where large tracks of land are not available, aggregating multiple smaller solar fields of 10 MW size in 50-acre tracks may be more feasible.  The modularity of solar equipment makes this possible as now hundreds of small residential and commercial systems are being aggregated by companies to make a single large "virtual" power plant.

Wind turbines offer higher power density per disturbed acre compared to solar, as only 2–5% of a wind farm’s total area is physically occupied by the turbine, allowing land to be used simultaneously for agriculture or livestock grazing. On average, wind farms require approximately 12–56 acres per megawatt (acre/MW) of nameplate capacity, primarily for spacing, buffer zones, and access. [41] However, turbines have a more visible footprint due to their height.

Aesthetic & Acoustic Considerations

Solar PV sites have minimal noise and visual disruption.  Slight noises from cooling fans, tracker motors, and transformers can be heard close to the equipment, but these noises are generally less than ambient noise at the site boundary.  The height of equipment in Solar farms is typically less than a single-story building (<25 ft).  Because solar panels are made of materials with the object of capturing light energy, glare is significantly less than other glass structures such as buildings, or lakes and ponds.  However, FAA has established specific restrictions and guidelines for solar panels near airfields that require a study, in Alteration Form 7460-1, proving the solar panels have no visual impact on pilots or air traffic control. [42]

Modern wind turbines can reach hub heights of 100–150 meters (300 to 500 ft), with blade tips extending to 200–250 meters, leading to visual changes on the landscape. Shadow flicker—moving shadows caused by rotating blades—can be mitigated through proper siting and modeling. Community reactions to turbine aesthetics vary widely.

Turbines generate aerodynamic and mechanical noise, typically about 70 dBa on the ground at the turbine and falls exponentially to under 45 dBA at the distance of nearby residences, which is quieter than typical urban ambient noise. [43] Wildlife impacts are a key concern, particularly bird and bat collisions.  Overall fatality rates for birds and bats by wind turbines are far lower than for buildings or vehicles. Wildlife impacts can be reduced through turbine curtailment strategies during migrations, improved siting around migration paths, and ongoing ecological monitoring.

Public Perception & Perceived Harm

Public perception plays a pivotal role in shaping the trajectory of wind and solar energy projects. While these technologies are broadly embraced as clean and sustainable alternatives to fossil fuels, local attitudes can significantly influence whether a project moves forward. Communities often weigh the environmental benefits against perceived disruptions to their daily lives, landscapes, and local identity. Even in areas supportive of renewable energy, skepticism may arise if residents feel excluded from decision-making or if past experiences with development have left lingering distrust.

Solar energy tends to enjoy relatively favorable public perception, especially when projects are sited on previously disturbed land like brownfields or industrial zones. However, in rural or agricultural regions, large-scale solar farms can spark concern over land use changes, visual impact, and potential glare. These reactions are often shaped by how the project is introduced to the community—whether through inclusive dialogue or top-down planning. Misconceptions about panel toxicity or long-term land degradation can further complicate acceptance, underscoring the importance of clear, accessible education.

Wind energy, while also viewed positively in principle, often faces more visible opposition. Turbines are large, prominent, and sometimes controversial symbols of change. Concerns about noise, wildlife disruption, and property values can fuel resistance, particularly in scenic or residential areas. Public perception in these cases hinges on transparency, trust, and how well developers engage with local values and priorities. Ultimately, the success of both wind and solar projects depends not just on technical feasibility, but on the social license granted by the communities they aim to serve.

6 Evolving Policy

Policy Volatility

Utility-scale wind and solar projects in the United States are subject to a complex set of regulations at the federal, state, and local levels. These regulations shape project timelines, site eligibility, environmental compliance, and access to transmission infrastructure. While designed to ensure public safety and environmental stewardship, regulatory complexity can introduce delays and increase development costs, especially for projects pursuing the Investment Tax Credit (ITC) or Production Tax Credit (PTC) under tight eligibility windows.

At the federal level, projects located on public lands or those with significant environmental impact must undergo reviews under the National Environmental Policy Act (NEPA). This often includes the preparation of Environmental Assessments (EA) or full Environmental Impact Statements (EIS), which can extend the permitting process by 12–36 months depending on project size, location, and the presence of sensitive species or habitats. Agencies such as the Bureau of Land Management (BLM) and U.S. Fish and Wildlife Service (USFWS) may impose further requirements if a site intersects with migratory bird corridors, endangered species habitat, or protected cultural resources. For wind energy in particular, developers must address risks to birds and bats under the Migratory Bird Treaty Act (MBTA) and the Bald and Golden Eagle Protection Act (BGEPA). While these laws do not prohibit wind development, they require the implementation of mitigation measures and may trigger compensatory permitting if mortality risks are identified.

At the state level, regulatory oversight varies widely. Some states, like Texas, offer a streamlined permitting process with fewer siting restrictions, while others, such as California and New York, require extensive review from environmental quality and utility commissions. Many states enforce renewable portfolio standards (RPS) or clean energy targets, which encourage wind and solar growth, but may also tie interconnection approvals or land-use authorizations to environmental performance metrics or labor standards. In states with competitive wholesale energy markets (e.g., ERCOT, MISO, PJM), renewable projects must also complete grid interconnection studies and negotiate agreements with transmission operators, which can introduce further delay.

Local jurisdictions play a critical role in zoning, noise limits, visual impact assessments, and community engagement. Solar farms may face opposition over land use, property values, and aesthetics, while wind projects often contend with regulations on turbine height, setback distances, and shadow flicker mitigation. Some counties have enacted outright moratoria or bans on wind or solar development, reflecting growing not-in-my-back-yard (NIMBY) resistance. Navigating local regulations often requires early engagement with landowners, planning boards, and environmental groups to avoid costly legal or procedural obstacles.

Efforts to streamline permitting, including proposed reforms to NEPA and the establishment of the Federal Permitting Improvement Steering Council (FPISC), aim to reduce regulatory barriers. However, as of 2025, most utility-scale projects still face multi-year development timelines, particularly when located near protected resources or requiring new transmission. Developers must build regulatory timelines into project planning and ensure full compliance with labor, environmental, and cultural preservation rules to maintain eligibility for federal tax credits and secure long-term project viability.

Incentives

Utility-scale wind and solar projects in the United States benefit from strong federal incentives structured under the Inflation Reduction Act (IRA), primarily through the Clean Electricity Investment Tax Credit (ITC) and the Clean Electricity Production Tax Credit (PTC). These two incentives, outlined in Sections 48E and 45Y of the Internal Revenue Code, are mutually exclusive and available for projects exceeding 1 megawatt in capacity that begin construction in 2025 or later. The ITC provides a one-time credit equal to 30% of a project’s eligible capital costs, contingent on compliance with prevailing wage and apprenticeship requirements. The PTC, on the other hand, offers a performance-based credit of approximately 2.75¢ per kilowatt-hour (in 2023 dollars, adjusted annually for inflation) for the first 10 years of energy generation. Projects that do not meet labor requirements receive only 20% of the base credit value.

Additional bonus credits of up to 20 percentage points are available under the ITC framework. These include a 10% bonus for meeting domestic content requirements—such as using U.S.-made steel, iron, and manufactured components—and another 10% for locating the project within an Energy Community, typically defined as an area impacted by the energy transition or recent job losses in fossil fuel sectors. As of 2024 IRS guidance, domestic content thresholds will increase in stages: 40% in 2024–2025, 45% in 2026, and 55% by 2027 and beyond. To help project developers comply, the IRS has introduced a safe harbor pathway that allows developers to use simplified acquisition cost estimates for qualification.

The decision between ITC and PTC is project-specific and depends on site resource quality, expected capacity factor, financing structure, and desired risk profile. Projects with high output, such as wind in the central U.S., often favor the PTC due to its long-term production-based benefit. Solar projects, especially those with higher upfront costs and lower output per installed megawatt, may benefit more from the upfront tax relief provided by the ITC. Both incentives are designed to be technology-neutral and remain in effect until national power sector emissions fall below 25% of 2022 levels, offering long-term market stability. These incentives lower capital risk, improve financing options, and help offset the continued cost advantage of imported components. Their structure reflects an evolving focus not only on clean energy deployment, but also on reshoring manufacturing, enforcing labor standards, and directing economic development to energy transition communities.

Policy revisions under the 2025 “One Big Beautiful Bill” Act (OBBBA) have introduced new limitations on eligibility timelines. Projects must begin construction before July 4, 2026, and must be placed in service by the end of 2029 (or 2030 if started mid-2026) to remain eligible for the full ITC or PTC. This accelerated schedule presents new risks for projects facing permitting delays, interconnection backlogs, or long equipment procurement timelines. Developers will need to closely monitor eligibility windows and adjust their construction schedules to retain access to credits. [44]

Incentives tied to domestic manufacturing have become increasingly important, as the U.S. continues to rely heavily on foreign supply chains. As of 2023, China dominates global production of both solar and wind components, supplying over 70% of polysilicon, 97% of wafers, and more than 60% of wind turbine components such as nacelles, blades, and towers. The U.S. ranks third in global wind manufacturing and trails far behind in solar manufacturing capacity. Provisions within the IRA—including the domestic content bonus and new manufacturing tax credits under Sections 45X and 48C—aim to reverse this trend. However, federal budget changes and uncertainty tied to proposed repeals or reforms, such as those outlined in the OBBBA, have caused delays or cancellations in some planned manufacturing investments.

The Investment Tax Credit (ITC) and Production Tax Credit (PTC) have been instrumental in accelerating the growth of renewable energy in the United States, particularly for solar and wind. Designed to jumpstart emerging industries, these incentives were never intended to be permanent fixtures. Over time, they helped drive down costs through economies of scale and technological learning. As these industries mature, the challenge now is to sustain momentum without relying on federal subsidies—a transition that appears not only feasible, but increasingly likely given current market dynamics and continued innovation.

7 Cost of Capacity & Energy

Solar PV and wind power offer long-term cost stability and potentially low-cost energy for certain locations.  Their feasibility for large-load applications depends heavily on regional resource quality, permitting timelines, and interconnection costs. Both technologies carry high up-front capital investment but benefit from extremely low operational expenses and zero fuel costs once installed.

Between 2005 and 2025, installation costs for solar and wind power plants fell dramatically—by nearly a factor of ten—as market scale and technological maturity accelerated. Today, average costs hover around $1,000 per kilowatt. While global prices for solar equipment continue to decline, U.S. prices have remained relatively flat due to steep tariffs on imported components. Domestic market volatility, driven by shifting federal and state policies, has further disrupted price stability, causing demand to fluctuate unpredictably. The data presented below represents a consolidated effort to synthesize insights from sources including NREL, LBL, US-EIA, DOE-SETO, Lazard, Bloomberg, project press releases, and the author's professional experience.

Capital and Operational Expenditures

The major components of capital expenditure (CAPEX) for utility-scale solar PV systems include photovoltaic modules, inverters, racking and mounting structures, balance-of-system components, and interconnection infrastructure. Nationwide 2025 install costs for most large-scale solar PV projects range from $1,050,000/MWac to $1,400,000/MWac. [45][46][47][48] Operations and maintenance (O&M) costs are relatively low for both technologies. Utility-scale solar PV projects report fixed O&M costs ranging from $11,000 to $18,800 per MW-year and negligible variable costs due to the absence of fuel. [45] Newer projects report less O&M costs compared to the older projects, in part because the industry has learned how to lower O&M costs and in part because of aging equipment in older plants. [45]

In this analysis for Solar PV, the AC power rating is used as the basis for $/MWac because it allows for a more consistent comparison with other generation technologies and aligns with the definition of Net Capacity Factor. Historically, studies reported solar capacity in DC terms, $/MWdc, based on the total rated output of the PV modules. When comparing such studies, a conversion is necessary. Utility-scale solar plants typically operate with a DC/AC ratio of approximately 1.25, though this ratio can range from 1.0 to 1.4 depending on system design. As a result, general cost metrics can be converted using the following approximation: [latex]$/MWac ≈ 1.25 × $/MWdc.[/latex]

Wind energy projects primarily incur CAPEX through turbine procurement, foundation construction, grid connection, and site access. The average installed cost for land-based wind power across the U.S. ranges from $1,200,000/MW to $1,700,000/MW, with variations driven by project size, turbine type, and site conditions.  [45] [16] Land-based wind projects have higher service requirements than solar due to mechanical complexity, with fixed O&M costs typically ranging from $24,500 to $40,000 per MW-year. Offshore wind can run 2-3x more in capital expenditure and operating expenditures than land-based systems because of their remote locations, the harsher conditions of the marine environment, and the need for specialized equipment and trained crews. [45]

Levelized Cost of Capacity and Levelized Cost of Energy

The Levelized Cost of Capacity (LCOC) for a utility-scale solar PV plant is approximately $151,00 per megawatt per year (±25%), factoring in annuitized capital expenditures (CAPEX), fixed operating expenses (OPEX) and performance degradation. While this cost is relatively low compared to other generation technologies, solar PV’s inherent non-dispatchability limits its effectiveness as a backup or standby resource. Capacity factors vary significantly across regions—from around 17% in the Northeast to nearly 30% in the Southwest—driven by differences in solar irradiance and system design. [49] With minimal variable operating costs and the absence of fuel expenses, the Levelized Cost of Energy (LCOE) for utility-scale solar PV projects (excluding incentives) typically ranges from $49/MWh for low-end costs and higher capacity factor to $125/MWh for high-end costs with a lower capacity factor (Figure 6.4 with supporting data in Table 6.1.).  The capital costs contribute about 7/8th of the LCOE as shown in Figure 6.6.

The Levelized Cost of Capacity (LCOC) for a utility-scale wind farm is estimated at $186,000 per megawatt per year (±25%), inclusive of annuitized capital expenditures (CAPEX) and fixed operating expenses (OPEX). Wind power offers compelling economic advantages due to its negligible variable operating costs and absence of fuel expenses. However, its viability is highly location-dependent: capacity factors range from under 30% in the Southeast to over 45% in the Central Plains and Upper Midwest, shaped by regional wind resources and turbine hub height. [16] As of 2025, the Levelized Cost of Energy (LCOE) for wind projects varies across the U.S., falling between $30 and $96 per megawatt-hour without incentives as shown in Figure 6.5 with data from Table 6.2. The capital costs contribute about 7/8th of the LCOE as shown in Figure 6.7.

These LCOE values are reduced by federal incentives: the ITC for solar projects currently covers 30% of eligible capital costs, lowering solar LCOEs to range from $38/MWh for low-end costs and higher capacity factor to $96/MWh for high-end costs with a lower capacity factor.  Similarly, the PTC for wind reduces costs to roughly $13–$76/MWh. The relative benefit of these incentives depends on project characteristics: for higher-utilization, lower-CAPEX projects, the PTC generally provides greater value, while lower-utilization, higher-CAPEX projects tend to benefit more from the ITC. In practice, this often means the PTC is more favorable for wind, given its typically higher capacity factors, while the ITC is more advantageous for solar. Because the PTC applies only for a limited period, its impact is front-loaded and does not lower lifetime LCOE to the same extent as the ITC. At these incentive-adjusted levels, both solar and wind frequently represent the lowest-cost sources of new electricity generation in the U.S., undercutting most fossil fuel and nuclear options. Even without incentives renewables in favorable insolation or wind locations have costs that fall in range with, or still below, many conventional generation technologies. Additional state or utility incentives, along with favorable tax depreciation schedules, can further enhance renewable project economics.

*Incentive numbers reflect the net effect on the project cost.  OPEX fixed includes a degradation augmentation cost.

**Incentive numbers reflect the net effect on the project cost.

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