A Comprehensive Analysis of Solar Easements in United States Energy Policy and Project Development

I. Abstract

A solar easement is a legal mechanism that ensures direct access to sunlight for a solar energy system on a parcel of land. This right to receive sunlight has not traditionally been recognized under United States (U.S.) common law, which emphasizes the value of land for development, not solar access. This white paper explores the technical and legal context of solar easements, their function in facilitating project permitting, and the regulatory framework in certain states. It addresses the major barriers to implementation such as negotiation difficulties and costs, and the effects of new and emerging technologies such as 3D solar modeling software, which help define and enforce easements and other easement rights with greater ease than historically possible. We also explore the possible future of solar access rights, including proactive urban planning and continued national energy policy. 

II. Introduction

As more and more parts of the United States transition to renewable energy, the successful implementation of solar energy systems, from rooftop-mounted to utility-scale, requires unimpeded access to sunlight. A solar easement is a legal instrument that grants a property access to direct sunlight sourced from an adjoining property for use as solar energy. It is typically structured as a negative appurtenant easement, meaning it restricts the owner of the burdened property (the servient estate) from developing their land in a way that would shade the solar energy system on the benefited property (the dominant estate). To be enforceable, this agreement must be created in writing, recorded with the local property records office, and, by doing so, "runs with the land" to bind all subsequent owners of both properties.

The necessity for such a legal instrument is rooted in the unique evolution of American property law. Unlike English common law, which recognized a "Doctrine of Ancient Lights" that could grant a right to sunlight through long-term, uninterrupted use, U.S. jurisprudence explicitly rejected this concept.6 Landmark cases, such as

Fontainebleau Hotel Corp. v. Forty-Five Twenty-Five, Inc., established a legal precedent that favored a landowner's right to build vertically, even if it cast a neighbor's property into shadow.7 This created a legal vacuum; in the United States, there is no inherent common law right to sunlight. The modern statutory framework for solar easements emerged as a direct policy response to this void, catalyzed by the energy crises of the 1970s which created an urgent national security and economic imperative to develop alternative energy sources.6 States like California became pioneers, enacting the first solar-related laws in the mid-1970s to provide a mechanism for property owners to secure the solar access their investments required.10 This historical context reveals that the entire legal structure of solar easements is fundamentally reactive. It was not born from a proactive valuation of sunlight as a resource but as a legislative "patch" to overcome a common law tradition that prioritized development. This reactive origin helps explain the patchwork of inconsistent solar access laws that exists across the states today, creating challenges for a cohesive national solar development strategy.

This white paper proposes that, in the absence of a common law right to sunlight, the solar easement provided by statute has become a necessary legal and engineering tool. It is needed both to protect private investments in solar technology and to provide the regulatory certainty that is necessary to ensure (1) ease of permitting a project, (2) prevent land-use conflicts in the future, and (3) allow for the large-scale use of solar energy to achieve national climate and energy goals.

III. The Engineering and Legal Framework of Solar Easements

The efficacy of a solar easement depends on the precise integration of technical engineering specifications and rigorous legal principles. The draftsmanship requires significant technical expertise to translate the physics of solar radiation into an enforceable property right. This convergence of geodesy and jurisprudence is what gives the easement its practical power; an abstract property right is defined not by traditional 2D boundary lines, but by celestial mechanics.

Technical Specifications: Defining the "Solar Skyspace"

The core of a solar easement from an engineering perspective is the clear, quantifiable definition of the three-dimensional volume of airspace—also called "solar skyspace" or "solar window"—that must remain obstruction-free.

The solar window is not static; it is dictated by the sun’s path across the sky, which changes with time of day and season. For this reason, the legal instrument must have strict scientific parameters. The easement must specify in degrees the upper and lower angles, both horizontal and vertical, that create the lower and lateral boundaries of the protected airspace. These angles must be measured from a permanent, identifiable benchmark on the dominant property, such as a surveyed brass cap set in concrete with a known elevation, to ensure long-term enforceability and prevent disputes arising from changes in grade or landscaping.

An easement's protections are not absolute but are tied to the times of day and year when solar energy collection is most productive and most vulnerable to shading. The protected hours are typically defined as a window around solar noon, often from 9:00 a.m. to 3:00 p.m..17 Critically, these parameters are usually calculated for the winter solstice (December 21st), the day when the sun is at its lowest altitude in the sky.17 An object that does not cast a shadow on the solar collector during this period of maximum solar vulnerability is highly unlikely to do so at any other time of the year, effectively guaranteeing year-round access.

Finally, the easement must define what constitutes a violation. Many statutes and ordinances have adopted a de minimis standard to prevent disputes over trivial shading. For example, Utah's statute defines the protected "solar skyspace" as one in which "not more than 10% of the collectable insolation shall be blocked" on any given clear day.4 Similarly, California's Solar Shade Control Act deems vegetation that shades more than 10% of a solar collector to be a private nuisance, providing a clear, quantifiable threshold for enforcement.

Legal Anatomy of an Easement Instrument

For the engineering specifications to be legally binding, they must be embedded within a properly constructed legal instrument that complies with state property laws.

First and foremost, a solar easement must be created in writing and recorded as are other conveyances of real property (deeds). It is filed in the office of the county recorder of the county in which the property is located (go tramp stamp your easement). This recordation gives public notice of the restriction and ensures the easement “runs with the land,” and is binding on any future owners of either the benefited property or burdened property.

The instrument must have clear and unambiguous identification of the parties and properties. This includes the full legal names of the grantors and grantees and the official legal descriptions (e.g., lot, block, and plat) of both the servient estate (the property subject to the easement) and the dominant estate (the property benefiting from it).4

The document must also detail the terms and conditions of the agreement. This includes the duration of the easement—which can be perpetual or for a specified term—and a clear articulation of any conditions that could lead to its termination, such as the permanent removal of the solar energy system.4

Finally, the easement should provide terms for consideration and enforcement. For example, it may state payment to the servient landowner for the granting the right and keeping the skyspace clear, or payment to the dominant landowner in the event of interference.4 The agreement should also state that it is enforceable by legal remedies such as an injunction or other civil action to compel the removal of an obstruction.5

IV. The Critical Role of Solar Easements in Project Permitting and Approval

A solar easement is more than a private agreement between neighbors; it is a powerful tool that provides the regulatory certainty needed to facilitate efficient and predictable project approval at the municipal level. By addressing the critical issue of solar access proactively, easements de-risk projects for developers, landowners, and permitting authorities alike.

Streamlining the Municipal Permitting Workflow

In local land-use decisions, ambiguity is a primary cause of time and expense. A properly created and recorded solar easement provides certainty to permitting authorities including zoning boards, planning commissions, and building departments. It functions as prima facie evidence that the principal issue of solar access—a typical challenge in a development scenario—has been resolved contractually between the parties in interest. It further eliminates a key variable from the board’s review, freeing them to evaluate the project based on compliance with building codes, setbacks, and other zoning requirements.

Easements also serve to preemptively address conflict through securing solar access rights early in the development process. For example, easements prevent situations of future land-use conflict that could put in jeopardy the success of a project even after the necessary permits were issued. A neighbor does not subsequently have the ability to construct an addition to their house or plant trees that violate the written easement, so the easement protects the long-term operational and financial viability of the solar investment. This assurance is particularly essential in utility-scale projects, where long-term site control and stability of operation are necessary as a prerequisite to financing.

The certainty provided by easements is also a foundational element for the adoption of modern, streamlined permitting processes. Automated platforms like SolarAPP+, developed with support from the National Renewable Energy Laboratory (NREL), are designed to grant instant permits for standardized residential solar projects by verifying compliance with a checklist of code requirements.29 A recorded solar easement can serve as a key piece of documentation that satisfies the "solar access" component of such a review, enabling an application to proceed through an automated workflow without the need for manual review or public hearings on that specific issue.31

Comparative State-Level Analysis

The legal framework for solar easements and access varies significantly across the United States, reflecting the absence of a unified federal approach. States can be categorized along a spectrum from those with comprehensive statutory protections to those with virtually none.

Table 1: Comparative Analysis of Solar Access Laws in Select States

Feature

California (Solar Rights Act)

Colorado (Solar/Wind Easements Law)

North Carolina (Solar Access Law)

Statutory Basis

Cal. Civ. Code §§ 714, 801, 801.5 11

C.R.S. § 38-30-168, § 38-32.5-100.3 12

N.C.G.S. § 22B-20, § 160D-914 34

HOA Restrictions

Prohibits "unreasonable" restrictions that significantly increase cost (>$1,000) or decrease efficiency (>10%).

Prohibits banning solar devices but allows "reasonable aesthetic" restrictions.12

Prohibits restrictions that prevent "reasonable use," as clarified by Belmont v. Farwig.36

Easement Creation

Explicitly creates the legal right to a solar easement, which must be written and recorded.11

Allows for voluntary creation of solar easements; must be written and recorded.12

Statute focuses on voiding restrictive covenants; easements are created under general property law.

Municipal Role

Allows cities/counties to require dedication of solar easements in new subdivisions. Berkeley has a highly technical ordinance.40

Local ordinances are common and can be highly specific, e.g., Boulder's "solar fence" concept for by-right protection.41

Municipalities cannot ban solar collectors, but they can regulate placement and screening, as long as they do not deny reasonable use.

States with little or no state statutory framework, such as Alabama and Arkansas, do not offer property owners the strong protections of states like California or Colorado. In those areas, a property owner’s access to solar is wholly dependent on entering into a private easement agreement via general common law, a process that provides much less certainty and legal power for the solar system owner.

Case Studies in Project Outcomes

The interpretation and enforcement of solar access rights has been highly influenced by important cases that have tested the limits of statutes and common law.

Prah v. Maretti (1982): This landmark Wisconsin Supreme Court case was a breakthrough in solar access law. The court reversed years of case law, finding that unreasonable blockage of sunlight for a solar energy system could be a private nuisance. This case represented an important judicial tipping point in questioning the desirability of solar energy in society, and balancing the development rights and a greater value of solar energy, as an emerging area of law, creating a new method of defending solar access when there is not easement.

Belmont Ass'n, Inc. v. Farwig (2022): This North Carolina Supreme Court case provides a contemporary application of judicial power in articulating a boundary to Homeowners' Association (HOA) authority. The court ruled that a general, discretionary architectural review clause in an HOA's covenants could not be used to effectively prohibit a reasonably sited solar installation.36 The decision clarified that under North Carolina's "reasonable use" statute, any restrictions must be explicit and cannot be applied in a way that renders the solar system ineffective.49 This case serves as a critical precedent for homeowners and installers facing ambiguous HOA restrictions in states with similar laws.

Zipperer v. County of Santa Clara: This California case serves as a crucial cautionary tale, underscoring the absolute necessity of an express, written solar easement. The plaintiffs argued that the trees growing on the adjacent county land were shading their solar system, and that when the county approved their home with solar panels, it implicitly granted them a solar easement. The court was very clear that it did not find this argument persuasive, determining that a solar easement is enforceable only if it is designated through a formal, written, and recorded instrument.” This ruling reinforces the engineering and legal fact that anyone who is seriously considering defending their multi-thousand dollar investment in a home solar energy system, should not do so based on informal agreements or assumptions.

The legal framework surrounding solar easements effectively creates a market-based policy tool. By defaulting the "right to obstruct" to the developer of the servient estate, state statutes do not grant an automatic right to sunlight. Instead, they create a legal structure for the solar user to purchase that right from their neighbor. This forces a negotiation where the value of development is weighed directly against the value of solar generation. If an agreement is reached, it signifies that the economic value of the guaranteed solar energy was higher than the perceived value of the lost development potential. This system facilitates an efficient, market-driven allocation of the "solar skyspace" resource, steering development in a manner that directs development to reflect renewable energy objectives without the need for prescriptive zoning for every parcel of land.

V. Challenges and Future Outlook

Despite their utility, solar easements are not without significant implementation challenges. However, rapid technological advancements and evolving policy trends are poised to reshape the landscape of solar access rights, making them more precise, accessible, and integrated into the fabric of urban and energy planning.

Implementation Hurdles

The voluntary nature of solar easements is both a strength and a primary challenge. A successful easement requires a negotiated agreement between neighbors, a process that can be complex and fraught with interpersonal difficulties.2 A neighbor on the servient estate may simply refuse to grant an easement, viewing it as an unacceptable encumbrance that limits their future development options and potentially diminishes their property value.9

The process also involves significant transaction costs. This includes legal fees related to the formation and evaluation of the agreement, which can vary from hundreds to thousands of dollars and involve surveying expenses to set permanent benchmarks and achieve exact angles; appraisal expenses to find reasonable compensation for the servient landowner; and recording fees with the state.54 For residential projects, these costs can be a substantial addition to the total system price.

Furthermore, the servient property may already be subject to pre-existing encumbrances, such as mortgages, utility easements, or mineral rights; the owners of these rights might need permission for the solar easement so it is not subordinate to their claims. This adds another point of negotiation and complication to the process.53

The Impact of Recent Developments in Related Technologies

Technological innovation is having a deep effect on what a solar easement means and how it is enforced, taking the process from conceptual guesswork to data-based certainty.

Advanced solar modeling software like Google’s Project Sunroof and commercial platforms such as OpenSolar have transformed what it means to define a solar window. Sophisticated tools use high-res aerial imagery and 3D modeling to replicate the path of the sun across the calendar year, quantify shading effects from neighboring buildings and topography, and systematically create the requisite legal document’s vertical and horizontal angles. The analytical work is no longer taxing, uncertainty disappears, and the technical analysis necessary to make a strong easement is available equally to all parties. Obtaining technical analysis to define a solar window typically involved a costly analysis from an engineer and there was an information advantage to the party with the supplemental reports. Now, a property owner can approach a neighbor with a verifiable 3D model and shade report, making the negotiation more transparent and potentially less adversarial.

For enforcement, drone-based surveying (photogrammetry) can produce highly accurate 3D models of existing conditions. This technology can be used to establish a definitive baseline at the time the easement is created and to later verify with objective data whether a new structure or tree growth violates the protected solar skyspace.

Future Trends in Solar Access Rights

The future of solar access appears to be shifting from reactive, individual easements to proactive, systemic integration within broader planning and policy frameworks.

A greater number of municipalities are incorporating solar access into urban planning and zoning codes through "solar-ready" ordinances.61 These regulations may require new subdivisions to be designed with optimal south-facing roof orientations, few obstructions, and in some cases, solar easements as a condition of development approval.63

While solar access is currently governed at the state and local level, the increasing urgency of national climate goals could create momentum for federal legislation, depending on the political climate. This is unlikely to take the form of a federally mandated solar right, but could manifest as federal incentives tied to state adoption of best practices, model ordinances, and streamlined permitting for solar, creating a more consistent regulatory environment for the interstate solar industry.66

Finally, solar easements will increasingly intersect with other property rights and energy models. They are a key consideration in the development of community solar projects and microgrids, where guaranteed solar access for a central array is essential for the project's financial and operational viability.69

VI. Conclusion

This white paper has established that the solar easement is a foundational legal and engineering tool in the advancement of solar energy within the United States. Born from the necessity to overcome a common law framework that did not protect a right to sunlight, the statutory solar easement provides a critical mechanism for securing the long-term viability of solar energy systems. The effectiveness of an easement is predicated on the precise integration of technical specifications—defining the three-dimensional solar skyspace with geometric and temporal accuracy—and a robust legal instrument that is properly written, recorded, and enforceable.

The analysis demonstrates that a well-executed solar easement is critical to de-risking the solar permitting process. Solar easements create certainty for municipalities and help pre-empt land-use conflict in the future, making project approvals easier; they are also a critical component of modern, automated permitting processes. The patchwork of state laws, from the comprehensive protections in California to the judiciary-defined rights in North Carolina, highlights the ongoing evolution of solar access policy. Key legal precedents, such as Prah v. Maretti and Belmont v. Farwig, have been instrumental in shaping this evolution. While significant challenges related to negotiation, cost, and public resistance remain, the transformative impact of technologies like 3D solar modeling and drone surveying is making easements more precise, accessible, and enforceable.

The central argument of this paper is that solar easements are a cornerstone of U.S. solar energy development. They function as an effective market-based mechanism to resolve the inherent conflict between private property rights and the public interest in renewable energy. As the nation continues its transition to a clean energy economy, the importance of these instruments will only grow.

Recommendations

To better utilize solar easements and accelerate solar deployment, we recommend:

• For Policymakers: State and local governments should collaborate to create and adopt model solar easement statutes and ordinances, e.g., those proposed by legal and policy organizations, to promote consistency and best practices across jurisdictions.71 Additionally, solar access considerations and easement checklists should be formally included in state and municipal permitting guides to educate officials, developers, and the public to help streamline the review process.72

• For Engineers and Developers: Industry professionals should leverage modern 3D modeling and drone surveying technologies to draft technically precise and minimally burdensome easements. The solar easement should be viewed as more than a late administrative hurdle; it should be considered early on as a key project de-risking strategy, and should be put in place before liability. The clear, certain, and legally enforceable easement documents and practices will be critical to protect solar investments over the long-term.45