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Solar Power

Introduction to Solar Power

Solar or electromagnetic radiation is the light emitted by the sun. This radiation can be captured and turned into useful energy for human activities. There are mainly two types of solar technology used to generate electricity: photovoltaics (solar PV) and concentrating solar-thermal power. This section focuses on the first of these two as it is more common on farms. As opposed to wind turbines that are mounted on towers, solar PV systems have an increased land footprint. Solar PV panels are generally installed in mounting structures that point panels towards the sun at an angle to maximize the capture of solar radiation through the year. These structures can be fixed or can move to track the sun over the course of a day (single axis trackers) or the year (dual axis trackers). Solar PV systems need inverters to convert direct current (DC) into alternating current (AC) that can be used to power electrical devices or to connected to the grid. Solar panels are connected in arrays with the electrical power being used at the site of generation or uploaded to the grid. The modular design of solar PV systems means that the size of a solar array can be  adjusted to small and large power supply needs, making it one of the most popular renewable energy technologies for farm-scale applications.

Farm Scale Solar Power

Small-scale solar PV systems can be used for off-grid operations where an energy storage system (e.g., batteries) are needed to provide energy at nights. However, grid connection is more popular regardless of the size of the system as this avoids the need for energy storage technology. Farm-scale PV systems can be installed on the roof of farm structures or situated on farm fields. The energy generated by a farm-owned solar PV system will displace energy purchased from the grid and reduced greenhouse gas (GHG) emissions if it replaces fossil-based electricity. Grid connected, farm-owned PV systems have three operating conditions depending on the solar electricity production and farm demand:

  • When the power produced by the PV system exceeds the farm demand, solar energy is used on the farm and the excess is exported to the grid. 
  • When the power produced by the PV system does not meet the farm demand, the additional energy is imported from the grid. 
  • When the PV system is not producing power (at night)  all of the farm demand is imported from the grid.   

Utility Scale Solar Power

The production of solar electricity has increased significantly in the last decade and it now represents 3% of U.S. total production. This has been driven by a more than 70% decrease in costs in the last decade.  Utility-scale solar serve multiple customers, as opposed to small scale systems that generally serve individual home or businesses and are generally installed on open land and near an existing substation or electric transmission line to facilitate connectivity. These systems can be large and thus have significant land requirements ranging from 5 to 7 contiguous acres per MW. This is where an opportunity between farmers and solar-utility companies arise. Farmland is often used for Solar PV development and can provide farms with a revenue source from land leasing agreements.

Visit our Energy Generation page to know more about MREC related solar projects and resources to other great informational pages.

Stray Voltage and Farm Solar Generation Caution

Farm solar generation can affect the amount of current on the neutral system conductor and therefore stray voltage levels. It is important to check with the utility company for approval before purchase and installing solar generation. In some cases, depending on the farm’s location on the utility system and the amount of solar energy planned for export from the farm, line upgrades may be required before generation is approved.

Resources

  • Assembly Bill 46 – Wisconsin State Legislature – 03/02/2023 – An Act to create 66.0401 (7), 196.378 (1) (e), 196.378 (4j), 196.491 (1) (h) and 196.491 (3) (a) 4. of the statutes; Relating to: requiring notice to political subdivisions and landowners regarding proposed large solar energy facilities, requirements for applying for certificates for large solar electric generating facilities, joint development agreements related to large solar electric generating facilities, and granting rule-making authority.
  • Solar Power in Your Community – U.S. Department of Energy, 2023 – This guidebook highlights new technologies and strategies to maximize the benefits of solar to all communities, such as combining solar with energy storage to improve resilience.
  • The Role of Anaerobic Digestion and Solar PV to Achieve GHG Neutrality in a Farm Setting by Horacio A. Aguirre-Villegas and Douglas J. Reinemann, 2022 – This paper models a small and large dairy farms in Wisconsin and evaluates the costs of solar PV and anaerobic digestion systems to make the dairy farms carbon neutral.
  • Solar Projects by The Manufacturing and Utility Bureau, 2022 – This is a Video presenting a solar project in Wisconsin and filing requirements for these types of projects.
  • Large Solar Installations in Rural Areas. Eric Udelhofen, OneEnergy – This is a presentation gave at the 2022 MREC Conference describing the portfolio of projects managed by OneEnergy, the gains and challenges, costs, and future projections for solar systems.
  • Farm Scale Solar, Experience, and Lessons Learned, Dave Daniels, MGD Farms – This is a presentation gave at the 2022 MREC Conference describing the installation of a solar system at MGD Farms.
  • Farmer’s Guide to Going Solar – Office of Energy Efficiency and Renewable Energy – This guide provides answers to common questions related to solar installations on agricultural land.
  • Large Scale Solar and Wind Deployment for Wisconsin by Renew Wisconsin, 2021 – This is a fact sheet presenting statistics on wind and solar projects in Wisconsin.
  • Where do large solar power plants pay off? by Gero Rueter Deutche Welle: Made for Minds, 2021 – This is a newsarticle seeking to answer the questions: Are solar power plants only profitable in the desert or also in gray northern Europe? Can the sun provide sufficient energy to factories? And where are we going to find space for PV modules?
  • Utility Scale Solar Farms in Wisconsin by Renew Wisconsin, 2020 – This report provides information on the operating utility scale solar projects in Wisconsin, benefits and drawbacks, and responds to commonly asked questions related to large solar systems.
  • Solar and Agricultural Land Use – by William Dean, Renew Wisconsin – 2019 – This article analyzes the intersections of utility-scale solar PV and conventional agriculture and found a number of interesting points centered on the change in crop production and harvested land in Wisconsin.
  • Overview of Opportunities for Co-Location of Solar Energy Technologies and Vegetation, by Jordan Macknick, Brenda Beatty, and Graham Hill National Renewable Energy Laboratory, 2013 – This study outlines some of the impacts large-scale solar facilities can have on the local environment, provides examples of installations where impacts have been minimized through co-location with vegetation, characterizes the types of colocation, and gives an overview of the potential benefits from co-location of solar energy projects and vegetation.
  • Losing Ground: Tracking the Rate of Farmland Loss in Wisconsin Counties, 1992 – 2010, by Aaron Thompson, 2012 – The purpose of this report is to provide local decision makers with an alternative source of county level farmland loss statistics.
  • Limitations of Agricultural Land UsePlanning Tools in Rural Wisconsin – by Douglas B. Jackson-Smith and Jill Bukovac, 2000, This paper critically examines statistical evidence for the effectiveness of farmland tax credit and exclusive agricultural zoning policies in Wisconsin.
  • Wisconsin Agriculture in Historical Perspective: Economic and Social Changes 1959-1995 – by Douglas Jackson-Smith, University of Wisconsin-Madison – This report summarizes a wide range of economic and financial performance indicators of agricultural production in Wisconsin and analyzes long terms patterns of change in the structure of agriculture in Wisconsin.

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