Solar Panels Power WCROC Swine Barn

L. Johnston, R. Acevedo, K. Sharpe, E. Buchanan, and M. Reese

September 2016

Researchers at the West Central Research and Outreach Center (WCROC) have been involved in a multi-faceted project called the “Greening of Agriculture.”  The overarching goal of this project is to reduce the reliance of modern production agriculture on fossil fuels.  One way to reduce this reliance is to shift energy demand from non-renewable fossil fuels to renewable energy sources.  Major food companies are asking agricultural producers to move in this direction, so we think this is a timely research topic.  Our project includes the renewable energy, dairy, agronomy, and swine programs at WCROC.  

Swine Barn Figure 1As part of the Greening of Agriculture project, we installed a solar photovoltaic (PV) system on the roof of the confinement swine finishing barn at WCROC in June 2015 (Figure 1).  The 27 kW system was manufactured by Heliene (a Minnesota company) and uses inverters manufactured by SolarEdge Technologies to convert the power from direct (DC) to alternating current (AC).  The solar system was sized with the idea that the electricity generated on the roof with a southern exposure to the sun could power the barn underneath.  Over the past couple years, we have been measuring the electrical power used by the barn.  We have measured the power consumed by: ventilation fans, natural gas heaters, lights, feed auger motors, and the power washer.  These represent at least 85% of the electrical power used in the barn.  Since installing and commissioning the solar system, we have measured the electrical power generated by the panels and have matched that production to the power used in the barn.  Over the 11 months from October 2015 to August 2016, the solar system generated 26,000 kWh of electricity.  During that same period, operation of the finishing barn required 23,000 kWh of electricity.  So, after nearly a year of operation, our roof-mounted solar system seems to be producing enough electricity to power the barn underneath it.

If one evaluates the balance of power during shorter periods of time, a slightly different picture emerges.  Monthly power use and production shows some mis-matches (Figure 2).  During December 2015 and January 2016, power required to operate the barn far exceeded electricity produced by the solar system.  However, in February through August 2016, production of electricity easily exceeded the power demands of the barn.  The low electricity production in December and January was caused primarily by snow drifts that formed on the panels which blocked the sun from striking the panels.  The manufacturer of the panels stated that snow covering the panels would melt off in a couple days, so there was no need to intervene.  We tested that claim by not scraping the snow from the panels and learned that some intervention might be needed to keep our panels clear in winter.  During summer, the panels generated more electricity than we needed to operate the barn.  So, the excess electricity was used to satisfy electrical power demands in other parts of the WCROC farm.  It is important to note that we have no capabilities to store electricity, so the barn still relies on power from the commercial power grid to operate during times of low solar production (i.e. nights, cloudy days, snowy days).

Figure 2

We will continue to monitor power consumption of our barn and electricity generated by our solar system to determine the long-term viability of solar PV arrays in pork production systems.  We are also evaluating power consumption on commercial pork production units and have modeled use of solar PV systems in some of these applications.  Stay tuned for more results on this exciting project.

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