Solar Overview

HOW PHOTOVOLTAIC (PV) SOLAR WORKS

A photovoltaic cell is made of semiconductor materials that absorb the photons emitted by the sun and generate a flow of electrons when the photons strike a semiconductor material, like silicon. A solar panel works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity. Solar panels actually comprise many smaller units called photovoltaic cells.

UTILITY-SCALE SOLAR AND THE GRID

Utility-scale solar has been generating reliable, clean electricity with a stable fuel price for decades. These types of projects provide the benefit of fixed-priced electricity during peak demand periods when electricity from fossil fuels is the most expensive¹.

SOLAR, HEALTH, AND DURABILITY

Photovoltaic technologies and solar inverters are not known to pose any significant health dangers to their neighbors². In the same way that a car windshield cracks but stays intact, the EVA layers in PV panels keep broken panels intact. The long-term durability and performance demonstrated over decades, as well as the results of accelerated lifetime testing, helped lead to an industry standard 25-year power production warranty for PV panels³. Additionally, the motors are highly reliable, DC brushless motors with extremely low maintenance requirements.

According to the Illinois Solar Energy Association:

Solar panels are safe to touch, whether attach to a home or installed in a solar farm in your neighborhood. Panels are primarily made of glass, aluminum, copper and other common materials. Solar farms also utilize steel racks to position panels, electrical cable and a small number of inverters and electric transformers to deliver power to the grid. All of this equipment is safe and contains the same materials that are found in household appliances. There are trace amounts of chemicals in solar panels that enable them to produce electricity. These compounds are completely sealed within the glass and coatings of the panels.

After their useful life, solar panels and equipment are easy to disassemble and recycle. Solar facilities are constantly monitored, and the owners have a business interest in keeping them well-maintained and operating properly. Solar plants are designed to withstand severe weather, and panels are built to last for up to 40 years. If solar panels are damaged, they can be quickly replaced with new ones.

Illustration of how a photovoltaic cell works from archive.epa.gov.

Figure 1. Solar Farm at the Indianapolis International Airport. Photo from indsolarfarm.com

SOLAR AND GLARE

Solar panels are designed to absorb sunlight, rather than reflect it, and most utilize anti-reflective glare front surfaces. Many projects throughout the US and the world have been installed near airports with no impact on flight operations. For example, the Indianapolis International Airport, as shown in Figure 1, has installed solar panels on 183 acres of its property ⁴. The United Kingdom and U.S. aircraft accident databases contain no cases of accidents in which glare caused by a solar energy facility was cited as a factor ⁵.

SOLAR AND NOISE

During the daytime when the array is generating electricity, ground-mounted solar inverters and transformers do produce a low humming noise, which is the majority of where sound associated with these systems come from. This quiet hum is similar to the sound level of a normal, everyday conversation, reaching roughly 65 dB ⁶. At 50 to 150 feet from the boundary of the arrays, any sound produced is inaudible ⁷.

SOLAR AND FIRE SAFETY

Solar panel modules contain only a small portion of materials that are flammable, which cannot self-support a significant fire. Additionally, there are built-in mitigation protections against extreme weather and fire within the technology itself. For instance, the inverters contain Type I Surge Arresters and are rated as Lightning Protection Level III ⁸. The overall panel system too has built-in wireless communication technology to all the panel tracker rows, meaning that the system can be monitored remotely ⁹.

As with other infrastructure development, solar developers cooperate with local fire departments to review project site plans and develop emergency response plans as necessary for the construction, operation, maintenance, and decommissioning of the solar systems. Solar projects provide gate access (e.g., Knox Boxes) to the fire department and other emergency service providers (see Figure 2).

Lastly, PV modules are commonly used on the roofs of people’s homes. Because of this, the UL requires them to comply with combustible materials testing and demonstrate low-flame-spread characteristics.

SOLAR AND WIND

The racking system is built to be configurable up to 140 mph winds ¹⁰, designed for the American Society of Civil Engineers (ASCE) wind speeds and local code. These systems contain a battery-backed controller, meaning that the systems can stow without needing external power from the grid to move. The panels will be able to achieve these optimal angles even during heavy storms or power outages.

There are cases where PV systems have withstood hurricanes, such as Hurricane Sandy in 2012 and during Hurricane Matthew in 2016. During Hurricane Sandy, the many large-scale solar facilities in New Jersey and New York at that time suffered only minor damage. In the fall of 2016, the US and Caribbean experienced destructive winds and torrential rains from Hurricane Matthew, yet one leading solar tracker manufacturer reported that their numerous systems in the impacted area received zero damage from wind or flooding ¹¹.

SOLAR AND DRAINAGE

According to the Illinois Solar Education Association, solar farms do not increase runoff and will improve soil and water quality. Storm water management plans are a required part of the solar development process. These plans are prepared by professional engineers to ensure that projects don’t contribute to erosion or flooding. The land on a solar farm is not paved and can be covered with vegetation that absorbs rain and runoff and helps recharge groundwater. Vegetation planted on solar farms create the added benefit of assisting in the prevention of erosion and improving soil quality¹².

Solar farm with grass underneath. Photo from asfmra.org.

SOLAR AND AGRICULTURAL IMPACT MITIGATION AGREEMENTS

Agricultural Impact Mitigation Agreements, or AIMAs for short, are agreements between solar project developers and the Illinois Department of Agriculture focused on ensuring that solar projects developed on agricultural land is restored to its pre-construction condition.

AIMAs focus on the restoration aspect of impacts that result from solar projects being constructed across a landowner’s productive farmland. AIMAs are negotiated with the solar developers prior to any construction in order to protect landowner interests and proactively address potential issues that result from project construction and/or subsequent site restoration¹³.

SOLAR IN THE WINTER

These systems are designed to handle the weight of Midwest snowfall, being able to withstand .75lbs/in² ¹⁴. The racking and modules are engineered and selected for the required snow loading according to local code. Additionally, panel modules on a tracking system, moving throughout the day with the sun, also shed snow accumulation. Figure 4 illustrates a single axis tracker system in northern Illinois in February completely cleared of snow after a heavy snowstorm the day before.

Designed for winter, the racking system has a small computer at every row of modules that tracks the sun based on its direction calculated from astronomical tables. It is not necessary for the sun to be shining for the system to track its location in the sky.

SOLAR AND THE ENVIRONMENT

From a compliance standpoint, in the beginning stages of development, solar developers initiate a natural resource review consultation with the Illinois Department of Natural Resources (“IDNR”) through IDNR’s Ecological Compliance Assessment Tool program, including a review of the Solar Project’s potential impacts to endangered species and wetlands. The solar developer is then required to comply with all applicable requirements resulting from said consultation.

According to the Audubon Society’s own science, the greatest threat to aviary species is climate change. The Audubon Society supports properly sited renewable energy sites, since “adopting renewable energy is critical to reducing pollution, lowering global temperatures, and preserving the places that birds need to survive”¹⁵.

Commonly asked questions about solar projects in your community.