In this comprehensive article, readers will gain an in-depth understanding of solar energy, its history, and how it works through photovoltaic and concentrated solar power systems. The environmental benefits, limitations, and concerns around solar energy are explored, such as reduced greenhouse gas emissions and impact on local ecosystems.
It will discuss the strategies for minimizing environmental impact, such as sustainable manufacturing and innovative technologies like Perovskite solar cells. Additionally, policy and regulation on national and global levels, as well as case studies showcasing successful solar energy projects, are examined to provide a well-rounded perspective on the role of solar energy in contributing to a more sustainable future.
Solar Energy: An Overview
Definition of Solar Energy
Solar energy refers to the power harnessed from the sun’s radiation. Essentially, it is a form of renewable energy derived directly from sunlight. This energy source is deemed renewable because it relies on a natural element (the sun) that is not depleted when used, unlike fossil fuels such as coal, oil, and natural gas.
As a clean, sustainable and non-polluting source, solar power is being increasingly recognized as an important alternative to conventional energy resources. The global adoption of solar technology has grown exponentially in recent years, driven by concerns about climate change, air pollution, and dwindling supplies of fossil fuels. Countries around the world, including major players like the United States, China, and India, are investing heavily in solar energy infrastructure to reduce their reliance on carbon-emitting sources, safeguard against energy price volatility, and meet their environmental goals.
History of Solar Energy
The use of solar energy dates back to ancient civilizations where they utilized the sun’s energy for various purposes such as heating and cooking. One of the earliest recorded examples of solar energy use dates to the 7th century BC, when Greeks and Romans used burning mirrors to focus sunlight and create fire.
The birth of modern solar technology can be traced back to the 19th century with the work of French physicist Edmond Becquerel who, in 1839, discovered the photovoltaic effect. This phenomenon occurs when light exposure generates an electric current in certain materials, subsequently laying the groundwork for the development of solar cells.
In 1954, Bell Labs introduced the first practical photovoltaic (PV) cell made of silicon, which converted sunlight into electricity at an efficiency rate of about 6%. This groundbreaking invention spurred significant research and investment in solar technology during the subsequent decades.
The modern solar energy industry gained momentum in the 1970s with growing concerns about global energy security, fossil fuel depletion, and environmental pollution. As a result, a number of policies and incentives were developed to promote the use of solar power. Today, solar energy is one of the fastest growing industries, with continuous advancements in photovoltaic cell efficiency, energy storage solutions, and the widespread adoption of supportive policies.
How Solar Energy Works
Solar energy is primarily harnessed through two main technologies: photovoltaic (PV) systems and concentrated solar power (CSP) systems. These methods convert sunlight into electricity and thermal energy, respectively, and can be used both at the residential level and for large-scale power generation.
Photovoltaic Systems
Photovoltaic (PV) systems are the most common form of solar energy technology. They work by utilizing solar cells, which are semiconductor materials that absorb sunlight and generate an electric current through the photovoltaic effect. These solar cells are typically made of silicon, although other materials such as perovskite and organic solar cells are being developed for improved performance and cost-effectiveness.
PV systems can be installed on a variety of scales, from individual panels on residential rooftops to large, centralized solar farms. The electricity generated by PV systems can be used to directly power homes, businesses, or be fed into the electrical grid. When combined with energy storage solutions like batteries, solar PV systems can provide a reliable and continuous source of clean electricity, helping to reduce carbon emissions and reliance on fossil fuels.
Concentrated Solar Power Systems
Concentrated solar power (CSP) systems, also known as solar thermal systems, use lenses or mirrors to focus sunlight onto a small area, generating high temperatures that are used to produce steam. This steam, in turn, drives a turbine connected to an electrical generator, which produces electricity. Unlike PV systems, which directly convert sunlight into electricity, CSP systems convert sunlight into thermal energy, which is then used to generate electricity.
There are four main types of CSP systems: parabolic troughs, linear Fresnel reflectors, power towers, and dish/engine systems. Each of these designs uses a different method for concentrating sunlight and generating thermal energy. Unlike solar PV systems, which can be easily scaled from individual panels to large solar farms, CSP systems are typically used for large-scale power generation in regions with abundant sunlight.
CSP systems also have the ability to incorporate thermal energy storage, which allows them to generate electricity even when the sun is not shining. This feature makes CSP systems more reliable and dispatchable, as they can provide power during cloudy days or at night, contributing to a more stable and resilient energy grid.
Environmental Benefits of Solar Energy
Solar energy has become increasingly popular over the past few years due to its various environmental benefits. This renewable energy source not only provides electricity, but it also plays a significant role in reducing the negative impact of human activities on the environment.
Reduction of Greenhouse Gas Emissions
One of the most significant environmental benefits of solar energy is the reduction of greenhouse gas emissions. Solar power systems do not produce any emissions during their operation, unlike traditional energy sources such as coal-burning power plants.
The burning of fossil fuels releases large amounts of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and other greenhouse gases that trap heat in the Earth’s atmosphere, resulting in global warming and climate change. By using solar energy to produce electricity, we can significantly reduce the amount of CO2 and air pollutants that are released, mitigating the effects of climate change.
Switching to solar energy supports the commitments of many countries under the Paris Agreement, which aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels. By transitioning to clean energy, governments and individuals can greatly contribute to saving the environment.
Decreased Dependence on Fossil Fuels
Solar energy reduces our dependence on fossil fuels, which are finite and non-renewable resources. As oil, coal, and natural gas reserves deplete, the competition for these resources increases, leading to price volatility and geopolitical conflicts. Transitioning to a renewable source such as solar energy can help diversify the energy portfolio of a country, promoting energy independence and increasing energy security.
Moreover, by relying less on fossil fuels, we can reduce the environmental degradation caused by mining, drilling, and extraction activities. Fossil fuel extraction not only destroys natural habitats and ecosystems but also results in water and soil pollution, which ultimately harms human health and the environment. Consequently, using solar energy helps protect our planet and its resources from further degradation.
Minimal Water Usage
Traditional power plants require enormous amounts of water for cooling purposes. In contrast, solar energy systems use minimal water during their operation, making them an environmentally-friendly alternative. The only water required for a solar energy system is for periodic cleaning of the solar panels, which is significantly less than what is needed for fossil fuel-based power plants.
By using less water, solar energy reduces the strain on the world’s freshwater resources. Access to an adequate water supply is already a significant global issue, and the increasing usage of freshwater due to rapid population growth, urbanization, and climate change exacerbates this problem. Thus, adopting solar energy can help alleviate pressure on this vital resource.
Reduced Air and Noise Pollution
Solar energy systems produce electricity quietly and without any air pollution, making them attractive for urban and residential installations. In contrast, traditional power plants emit a range of pollutants, such as sulfur dioxide, nitrogen oxides, and particulate matter, which contribute to respiratory and cardiovascular diseases.
Additionally, noise pollution caused by conventional power plants can negatively impact human health and disrupt ecosystems. Installing solar panels in urban areas can help reduce both air and noise pollution while providing clean energy for the growing population.
Land Use and Habitat Preservation
While solar energy does require land for the installation of solar panels, their impact on land use and ecosystems is significantly less than that of fossil fuel extraction and production. Solar panel installations can also be integrated into existing infrastructure, such as rooftops, parking canopies, and agricultural lands, without compromising the area’s natural ecosystems and habitats.
Moreover, solar energy production does not produce hazardous waste, unlike the nuclear power industry, which generates radioactive waste that must be stored and managed for thousands of years. By choosing solar energy, we can help protect fragile ecosystems and habitats, promoting biodiversity and sustainable development.
In summary, solar energy offers a myriad of environmental benefits, from reducing greenhouse gas emissions and dependence on fossil fuels to preserving water resources, reducing air and noise pollution, and minimizing impacts on land and habitats. By transitioning to solar energy, we can move towards a more sustainable future for our planet and its inhabitants.
Limitations and Environmental Concerns
Energy Production Variability
One of the primary concerns when it comes to solar energy is its variability in energy production. Since solar panels rely on sunlight to generate electricity, they cannot produce power during nighttime or cloudy days. Seasonal changes in sunlight availability also affect the energy output, leading to decreased generation during winter months. These fluctuations in energy production can create a challenge for grid operators, who need to ensure a stable and constant supply of electricity to meet the demand.
Moreover, the efficiency of solar panels can decrease over time due to various factors such as dirt accumulation, temperature changes, and degradation of materials. As a result, the real-world performance of solar panels often differs from their theoretical potential. Although advances in solar technology have significantly improved the efficiency of panels, energy production variability remains a major concern.
Manufacturing and Disposal of Solar Panels
Solar panels may seem like a clean source of energy at first glance, but their manufacturing process involves the extraction and processing of various raw materials, which can have negative environmental impacts.
Materials Extraction and Production
The production of solar panels requires the extraction of various metals, such as aluminum, silicon, and silver, which have various environmental impacts. Mining and refining these materials can lead to habitat destruction, water pollution, and greenhouse gas emissions.
Moreover, some of these materials are finite resources, raising concerns about their long-term availability and the sustainability of solar panel production. In addition to metals, the solar panel manufacturing process requires the use of chemicals, such as hydrofluoric acid and sulfur hexafluoride, which can be harmful to both the environment and human health if not properly managed. Proper disposal and recycling of these chemicals are essential in minimizing their negative impacts.
Waste Management and Recycling
Solar panels have a lifespan of around 25-30 years, after which their efficiency declines and they need to be replaced. This leads to a significant volume of waste, comprising glass, metal, and other materials. Proper recycling and disposal of these waste materials are crucial in ensuring that solar energy remains a sustainable and environmentally friendly option.
Solar panel recycling is a rapidly growing industry, and advanced recycling techniques can recover up to 95% of the materials used in solar panels. However, recycling facilities need to be equipped and ready to handle the expected increase in solar panel waste as more panels are deployed and reach the end of their lifespan.
Land Use for Large Scale Solar Projects
Large-scale solar installations, such as solar farms, can occupy vast amounts of land, leading to concerns regarding land use and its associated environmental impacts. The development of these projects may lead to the destruction of natural habitats, displacement of wildlife, and the conversion of agricultural or other productive land into solar facilities. As solar energy continues to expand, it is essential to find ways to minimize land use by deploying solar panels on existing structures, such as rooftops and parking lots, or using dual-purpose land, such as integrating solar arrays into agriculture or wildlife habitats.
Impact on Local Ecosystems and Biodiversity
Solar installations can have both positive and negative impacts on local ecosystems and biodiversity. On one hand, solar farms can provide a habitat for certain species or act as a refuge for wildlife in disrupted landscapes. On the other hand, the construction and operation of solar projects can lead to habitat destruction, disruption of migratory patterns, and even direct harm to wildlife, such as birds being killed by concentrated solar power systems that produce intense heat.
Water Consumption for Cleaning Solar Panels
Although solar panels are often considered a low-water-use energy source compared to other forms of energy generation, they require regular cleaning to maintain their efficiency, which can consume a significant amount of water, especially in large-scale installations. In areas with water scarcity, this can pose a challenge, as water resources need to be allocated efficiently. Advancements in water-saving cleaning technologies and the use of alternative cleaning methods, such as using robots or dry cleaning, can help mitigate this concern.
Although solar energy offers a promising solution for reducing greenhouse gas emissions and reliance on fossil fuels, it also has its limitations and environmental concerns. Addressing these challenges is crucial for ensuring the long-term sustainability and success of solar energy as a key component of the global energy mix.
Strategies for Minimizing Environmental Impact
As the world becomes increasingly aware of the environmental impact of human activities, new strategies are emerging to minimize the ecological footprint. From manufacturing practices to renewable energy generation, minimizing environmental impact should be a key concern across sectors. In this section, we will discuss several strategies for reducing the impact that solar power — a popular renewable energy source — has on the environment.
Sustainable Manufacturing Practices
One of the most direct ways to minimize the environmental impact of solar power is by adopting sustainable manufacturing practices. This can help mitigate the waste and energy consumption associated with producing solar panels. Some key elements of sustainable manufacturing practices for solar panels include:
- Resource efficiency: Optimizing the use of raw materials, energy, and water in the manufacturing process, reducing waste and resource consumption.
- Renewable energy: Integrating renewable energy sources into the manufacturing process, reducing the reliance on fossil fuels.
- Green procurement: Using environmentally friendly, sustainable, and ethically sourced materials within the supply chain.
- Waste management: Ensuring proper disposal of waste, implementing recycling and recovery programs to prevent hazardous waste from entering the environment.
- Energy-efficient transportation: Utilizing low-emission, fuel-efficient, or electric vehicles for the transportation of solar panels and components within the supply chain.
Improved Solar Panel Recycling Programs
When solar panels reach the end of their lifecycle, proper recycling is essential to minimize environmental impact. Developing improved solar panel recycling programs can help recover valuable materials like silicon, aluminum, and silver, and keep hazardous materials like lead and cadmium out of the environment.
Effective solar panel recycling programs should incorporate the following:
- Recycling infrastructure: Establishing well-equipped recycling facilities with the technology and capacity to process a large volume of solar panels.
- Regulation and policy: Implementing legislation that mandates solar panel recycling and sets minimum recycling standards.
- Financial incentives: Offering incentives to encourage solar panel manufacturers and users to recycle their products responsibly.
- Research and development: Focusing on innovation and finding new recycling techniques to increase recycling efficiency and reduce costs.
- Awareness and engagement: Promoting responsible recycling and educating the public on the importance of solar panel recycling.
Dual-Use Solar Installations
Dual-use solar installations, also known as agrivoltaics, can help minimize the environmental impact of solar power by enabling solar energy production alongside existing land use practices, such as agriculture or conservation.
Some benefits of dual-use solar installations include:
- Preserving agricultural land: By co-locating solar panels with crops, more efficient use of land is achieved without compromising agricultural production.
- Reducing habitat loss: Integrating solar panels into existing ecosystems can help minimize habitat loss for wildlife and maintain biodiversity.
- Improving water efficiency: Some studies have shown that shading provided by solar panels can reduce water evaporation, improving water-use efficiency in agriculture and reducing the overall water footprint of solar power generation.
- Increased energy production: Combining solar panels with other land-use practices can lead to improved energy production by utilizing available land resources more efficiently.
Innovative Solar Technologies
Investments in research and development of new solar technologies are essential to minimizing the environmental impact of solar power while improving efficiency and affordability. Let’s take a look at several promising innovative solar technologies:
Perovskite Solar Cells
Perovskite solar cells are an emerging photovoltaic technology that has demonstrated significant potential for improved efficiency and cost reduction. Compared to traditional silicon solar cells, perovskites have a simpler manufacturing process that requires fewer materials and less energy, contributing to a reduced environmental footprint. Additionally, perovskite solar cells can be made semi-transparent and flexible, enabling their use in a wider range of applications.
Floating Solar Panels
Floating solar panels, or floatovoltaics, are an innovative solution for areas with limited land availability. By installing solar panels on bodies of water, such as reservoirs, lakes, and ponds, the land can be utilized for other purposes, mitigating ecosystem disruption caused by land-based solar installations. Floating solar panels can also improve water conservation by reducing evaporative losses and promoting cooler water temperatures, potentially benefitting aquatic life.
Building-Integrated Photovoltaics
Building-integrated photovoltaics (BIPV) combine solar panels with building materials, such as glass or roofing, removing the need for separate solar panel installations. BIPV systems can reduce the environmental impact of solar energy by decreasing the amount of land and materials required for solar installations. Moreover, BIPV systems can lead to increased energy efficiency in buildings and enhance their aesthetic appeal.
By adopting sustainable manufacturing practices, improving recycling programs, leveraging dual-use solar installations, and investing in innovative solar technologies, we can work together to minimize the environmental impact of solar power and move towards a more sustainable future.
Policy and Regulation for Solar Energy and the Environment
Solar energy is a vital, clean, and abundant source of power that is increasingly becoming a fundamental part of global energy plans. Policies and regulations at international, national, and local levels are essential to foster the growth of the solar sector, encourage sustainable practices, and protect the environment.
This section examines global initiatives and agreements, national policies and regulatory frameworks, subsidies and incentives for solar energy adoption, community solar programs, and grid integration and energy storage solutions.
Global Initiatives and Agreements
International collaboration is crucial to accelerate the adoption of solar energy worldwide. Numerous global initiatives and agreements have been established to promote the use of renewable energy sources, including solar power.
The Paris Agreement, the most recent international treaty on climate change, has been ratified by 190 parties. Under this agreement, countries pledge to reduce greenhouse gas emissions and work together to limit global temperature increase to well below 2 degrees Celsius above pre-industrial levels. The agreement also encourages financial and technological support to help nations transition to renewable energy sources, such as solar energy.
Initiatives like the International Solar Alliance, a treaty-based intergovernmental organization, aim to promote solar energy, develop solar projects and infrastructure, and mobilize investments in the solar sector. The alliance provides a cooperative platform for countries to research, develop, and implement effective policies, standards, and regulations, and to share knowledge and expertise.
National Policies and Regulatory Frameworks
National policies and regulatory frameworks play a significant role in supporting and guiding the development of the solar industry. Governments worldwide have implemented various policies, regulations, and targets to incentivize solar energy generation and consumption.
Feed-in tariff (FIT) policies, renewable portfolio standards (RPS), and net metering programs are common policy instruments that encourage solar energy adoption. FIT programs guarantee a fixed price for solar electricity generated by individuals or businesses and fed back into the grid. RPS mandates electricity suppliers to produce a specific percentage of their power from renewable sources, including solar. Net metering programs credit solar system owners for the surplus electricity they feed into the grid, promoting decentralized solar generation.
To support environmentally sustainable practices, many governments have established building codes and regulations that require new constructions to meet green building standards and integrate solar energy systems.
Subsidies and Incentives for Solar Energy Adoption
Financial incentives and subsidies play a crucial role in encouraging the adoption of solar energy systems. Governments worldwide offer various types of direct and indirect financial support to consumers and businesses.
Direct financial incentives include tax credits, grants, and rebates which reduce the initial investment cost of solar systems. For example, the United States offers a federal investment tax credit (ITC), which allows home and business owners to claim a percentage of the installation cost of a solar energy system.
Indirect incentives, like low-interest loans, green bonds, and carbon pricing, help lower the financial barriers to adopting solar energy. Carbon pricing mechanisms, such as carbon taxes and cap-and-trade systems, can incentivize businesses to invest in renewable energy, including solar power, to reduce their greenhouse gas emissions.
Community Solar Programs
Community solar programs enable greater access to solar power, particularly for low-income households and renters who may not have the financial resources or suitable rooftops for solar installations. These programs allow individuals and businesses to invest in or subscribe to shared solar projects and receive credits on their electricity bills proportional to their share of the energy generated.
Community solar projects provide environmental benefits, including reduced greenhouse gas emissions and lowered dependence on fossil fuels. They also create local job opportunities and generate revenue for the community.
Grid Integration and Energy Storage Solutions
As solar energy use increases, grid integration and energy storage technologies become essential to ensure grid stability, reliability, and efficiency.
Smart grid technologies allow better monitoring and control of energy production, distribution, and consumption, making it easier to integrate solar power with the conventional power grid.
Energy storage solutions, such as batteries and pumped hydro storage, help balance solar energy supply and demand by storing excess solar power during peak generation hours and releasing it when needed. This not only improves grid stability but also reduces the need for backup fossil fuel power plants, leading to lower greenhouse gas emissions.
Policies encouraging research, development, and deployment of energy storage technologies will play a crucial role in harnessing solar power’s full potential as a sustainable and scalable energy source.
Case Studies: Successful Solar Energy Projects and their Environmental Impact
Large-Scale Solar Power Plants
Solar power plants are one of the most prominent renewable energy projects in various countries due to their ability to produce clean and sustainable energy. Two examples of successful large-scale solar power plants are the Noor Complex in Morocco and the Kamuthi Solar Power Project in India.
The Noor Complex, located in Ouarzazate, Morocco, is the world’s largest concentrated solar power (CSP) plant with a total capacity of 580 MW. The plant has a successful track record of providing clean energy to over 1.1 million homes in Morocco while reducing carbon emissions by nearly 760,000 tons per year. The use of CSP technology in Noor Complex allows for the storage of excess solar energy for use during the night or on cloudy days, ensuring a more reliable energy supply.
In India, the Kamuthi Solar Power Project in Tamil Nadu is one of the largest solar photovoltaic (PV) power plants in the world. With a total capacity of 648 MW, the plant covers an area of 2,500 acres and powers about 150,000 homes. The solar power generated at the project site helps reduce carbon emissions by approximately 300,000 tons per year. The project aided in India’s aim to generate 40% of its energy from renewable sources by 2030.
Rooftop Solar Installations
Rooftop solar installations are becoming increasingly popular, especially in residential and commercial sectors. Such installations enable building owners to generate their power, reducing reliance on the central grid and lowering energy bills.
Google’s campus in Mountain View, California, is one such example, with its solar panels generating 1.9 MW of clean energy annually. Google’s rooftop solar installation has offset the campus’s total carbon emissions by 90%.
In Vermont, the community-owned solar project, Solar Holler, has helped nonprofit organizations install solar panels on their roofs, lowering their energy costs and reducing their environmental impact. In addition to offering affordable and green energy to nonprofits, the project also provides training opportunities for local workers to gain hands-on experience in solar installation jobs.
Remote and Off-Grid Solar Energy Systems
Remote communities often lack access to reliable electricity. Solar energy is a viable solution to such issues. Solar Energy Solutions Tokelau (SESTK) is a prime example, as this small island nation in the Pacific transitioned from relying on diesel generators to 93% solar and battery energy storage systems. The integrated systems now supply electricity 24/7 to a population of 1,411, effectively reducing the island’s environmental impact and dependence on costly fuel imports.
Ta’u island, part of the American Samoa, is another example where a solar-battery microgrid installed by Tesla offers 100% renewable energy to the island’s 600 residents. The installation has already saved the island from procuring nearly 109,500 gallons of diesel annually, significantly reducing both CO2 emissions and fuel costs.
Emerging Markets and Rural Electrification
Emerging economies, such as those in Africa, have seen substantial growth in solar installations targeting rural communities. Off-grid solar home systems have become increasingly popular, offering affordable energy access in remote areas. Companies like M-KOPA and d.light have provided millions of off-grid solar solutions across Africa, empowering rural communities to generate their energy and reducing dependency on fossil fuels while promoting social and economic development.
Moreover, solar-powered water pumps, such as those implemented by SunCulture in Kenya, have significantly impacted agriculture. The technology provides farmers with reliable and cost-effective irrigation, improving crop yields and reducing dependence on unpredictable rainfall patterns.
Urban Solar Initiatives and Smart Cities
Cities around the world are embracing solar energy as a way of promoting sustainable development and reducing their carbon footprint. The Solarize NYC program in New York City encourages communities to purchase solar energy systems collectively, making installation more affordable and accessible than individual purchases.
In Barcelona, Spain, the Solar Thermal Ordinance requires all new buildings and those undergoing substantial renovations to integrate solar energy systems for generating hot water. This mandate has contributed to increasing the city’s sustainability and energy efficiency.
By analyzing these case studies, we can see solar energy projects’ significant potential to reduce carbon emissions, provide affordable and clean energy, and promote sustainable development. As technology advances and the cost of solar energy continues to decrease, it will become more feasible for even more communities and industries to embrace solar power.
Frequently Asked Questions
How does solar energy reduce environmental impact compared to fossil fuels?
Solar energy is a renewable resource, produced without emitting greenhouse gases or other pollutants. In contrast, burning fossil fuels generates harmful emissions, contributing to air pollution and climate change. Adopting solar power significantly decreases the environmental footprint and promotes sustainability.
What is the significance of solar energy in mitigating climate change?
Solar energy plays a critical role in reducing greenhouse gas emissions by replacing fossil fuel-based electricity generation. As solar power produces no direct emissions, increasing its usage contributes to achieving global clean energy targets and limiting the rise of global temperatures.
How does solar energy help conserve water resources?
Solar energy systems, unlike fossil fuel and nuclear power plants, require minimal water resources for operation. By opting for solar power, pressure on water resources is reduced, contributing positively to water management and conservation strategies.
What is the effect of solar energy on air quality?
Using solar energy improves air quality by eliminating the release of harmful pollutants, such as nitrogen oxide, sulfur dioxide, and fine particulates, generated from burning fossil fuels. This contributes to a healthier environment and minimizes the risks of respiratory and cardiovascular diseases.
Do solar panels have any negative effects on the environment?
Solar panels have an overall positive impact on the environment. However, manufacturing and disposal of solar panels do raise concerns regarding energy consumption, resource extraction, and waste generation. Proper recycling and waste management practices can alleviate these potential negative effects.
How does the land use of solar farms compare to other energy sources?
Solar farms require a significant amount of land; however, their land-use efficiency is comparable or better than other renewable energy sources like wind farms or biomass. Additionally, solar farms may be placed on otherwise unproductive land or built on rooftops, reducing their potential land-use impacts.