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.
- Solar – International Energy Agency (IEA)
- Solar explained – U.S. Energy Information Administration (EIA)
- Solar Energy Technologies Office – Office of Energy Efficiency and Renewable Energy
- Solar Power – NewScientist
- InSPIRE Project – U.S. Department of Energy
- Solar Energy – Renew Wisconsin
- Solar photovoltaic energy for agricultural operations – Farm Energy – Iowa State University