Local Opinion: A triple bottom line for Arizona

Arizona faces urgent challenges for agriculture, water and power. First, a drastic reduction in Lake Mead’s water level, now at 28% of capacity, threatens irrigated agriculture in our state. Second, Arizona faces increased energy demands during extreme heat events, both in our state and neighboring states joined through the “Western Interconnection” power grid. Third, Arizona needs abundant, affordable, clean energy for our growing economy that protects air quality and public health.

Arizona farmers and energy developers can mitigate all three challenges using research pioneered at the University of Arizona Biosphere lab. Solar panels interspersed with row crops improve water efficiency and solar power production. This dynamic combination is known as “agrivoltaics,” or agriculture-based photovoltaics. A solar panel providing partial shade to crops reduces water evaporation from soil and water transpiration from leaves. The crop under the solar panel provides a cooling effect for the panels, which are more efficient when they stay cool, allowing them to remain more productive on the hottest days, when power is most needed for air conditioning.

When University of Arizona researcher Greg Barron-Gafford tested this technology using three local Arizona crops (chiltepin peppers, jalapeño peppers, and tomatoes), his team learned that chiltepins and tomatoes produced three and two times as much fruit when planted under solar panels. Jalapeños produced about as much fruit under solar panels, while reducing water use by 65%.

Tucsonans can easily view agrivoltaic pilot projects at Manzo Elementary School and University High School.

Benefits of solar power

Arizona is one of the largest markets for solar power with the fifth-highest level of installed capacity of all 50 states.

Solar production is the ideal resource because Arizona has about 300 sunny days each year and air conditioners run harder when the sun is high. Agrivoltaic projects enhance a technology which Arizonans already need, while raising efficiency of energy generation and maximizing the economic output of our agricultural land. Using crops under solar panels keeps them cooler and Dr. Barron-Gafford’s team measured a 16-degree cooling effect. The cooler panel temperature produces a 3% efficiency improvement during the hottest months from May to July.

Because solar efficiency gains over crops are highest during the hottest months, these projects can improve the reliability of our state electric grid when we need it most. Increased power output from a given number of solar panels is an alternative to backup plants that come with pollution and unequal impacts, like the proposed Coolidge methane gas-fired plant expansion. The Arizona Corporation Commission rejected this plant because the utility had not addressed cost concerns or considered alternative plans, but utilities across Arizona must expand power infrastructure to support economic growth and ensure reliable service during extreme weather.

How can Arizona deploy agrivoltaics at scale?

First, Arizona’s higher education institutions and the state Department of Agriculture should collaborate to identify funding for more research, both to study additional crops of interest to Arizona’s farmers and to understand agrivoltaic applications in warmer areas, including Yuma County. The early results from Biosphere 2 are promising, but further research means that more farmers will benefit from the technology.

Second, the state needs to organize an efficient process to develop more energy storage technologies. Solar panels generate peak production between 11 a.m. and 3 p.m. but the power demand peaks between 7 p.m. and 11 p.m. (consider AC, lighting, personal entertainment and retail-restaurant businesses). Lithium-ion batteries are in short supply because of the popularity of electric vehicles, but several other battery technologies will be available soon.

The Arizona Legislature and the Corporation Commission must plan for the future of our power grid today. This should ensure that Arizona farmers have access to agrivoltaic technology to save water, increase crop production, and diversify revenue sources using solar leases. All Arizonans benefit from stable electricity bills, reliable power, and reduced air pollution.