Agrivoltaics: Can ‘sunlight income’ become an alternative to overcome falling farm profits?

As the government pushes to install agrivoltaic systems to boost farm income and expand renewable energy, empirical data has been released showing that crop yields beneath the facilities can decline by as much as 32% due to insufficient sunlight. Experts point out that, to practically preserve farmers’ income, it is urgent to select crops optimized for the under-panel environment and establish cultivation techniques.

The Industrial Education Institute stated this at a seminar held on April 29 under the theme, “Government Policy, Recent Trends, and Commercialization Strategies for Agrivoltaics and Sunlight-Income Villages,” where Lee Chaewon, an agricultural researcher at the National Institute of Crop Science, presented empirical data evaluating crop productivity beneath agrivoltaic systems.

▲Agrivoltaics, unavoidable decline in crop production=According to researcher Lee Chaewon’s presentation that day, clear environmental changes were observed in paddy fields beneath installed agrivoltaic facilities compared with ordinary open fields. Shading caused by solar panels increased as light intensity grew stronger, showing a difference in light quantity of more than 30% at maximum compared with open fields.

These environmental changes had an immediate impact on crop growth. In the case of rice, reduced photosynthetic efficiency caused etiolation, with stems growing thinner and longer. In particular, rice culm length tended to decrease beyond a certain shading rate, while the number of nodes and grains per panicle also fell, reducing yield.

In fact, rice yields beneath agrivoltaic systems fell by about 13–19% compared with open fields. Quality deterioration was also confirmed, including higher protein content in rice and a lower proportion of fully ripened grains.

Field crops were also significantly affected. Sweet potatoes decreased by about 18–32% compared with open fields, corn by about 18%, and soybeans by about 13–24%. Researcher Lee Chaewon said, “For tuber crops such as sweet potatoes, insufficient sunlight prevented proper tuberous root formation, greatly reducing marketability.”

Lodging and pests and diseases are also matters requiring caution when installing agrivoltaics. This is because overgrown crops have weaker stems, making them more likely to fall over during typhoons or heavy rain and leading to pre-harvest sprouting damage at harvest time. In addition, in environments with low sunlight and high humidity, the incidence of rice bacterial leaf blight and wheat powdery mildew tended to increase.

The convenience of farm work is another issue to solve. Solar support structures can restrict the operation of large agricultural machinery such as tractors and combines. This is why it is essential from the design stage to secure pillar heights of at least 3.5 meters and sufficient spacing between pillars.

▲Expectations for higher farm income=Although reduced crop production is unavoidable, expectations are growing that stable electricity generated by agrivoltaics will become a new source of farm income.

According to Professor Lim Cheolhyun of Korea Institute of Energy Technology, income from cultivating agrivoltaics (9,872,000 won) and rice (1,141,946 won) totaled 11,013,946 won (based on 20a), which was 6.46 times higher than the control plot (1,703,078 won).

In particular, income expectations are projected to rise even further when high-income crops are cultivated together with agrivoltaics. Combining blueberries, a representative high-income crop, with agrivoltaics produced income of 32,027,474 won, generating about 6 million won in additional profit compared with the control plot.

Professor Lim Cheolhyun advised, “The return per unit area for blueberries increases by up to 18.7 times compared with rice. For large-scale development, rice is advantageous, while for small-scale development, it is better to cultivate high-value-added crops.”

▲Future tasks=Participants that day agreed that agrivoltaics provide farmers with additional revenue in the form of ‘sunlight income,’ but requested technical improvements to increase acceptance in the agricultural field.

One participant said, “Going forward, we need to identify the optimal shading rate for each crop, and agricultural and engineering experts should collaborate from the facility design stage so that farm machinery operations can proceed smoothly.”

The National Institute of Crop Science also plans to focus on selecting crops and varieties optimized for cultivation beneath agrivoltaic systems. It is expected to identify shade-tolerant varieties that grow well even in shaded environments and establish appropriate fertilization amounts and planting densities to compensate for insufficient light.

Researcher Lee Chaewon emphasized, “Agrivoltaics are a model that can achieve both farmland preservation and renewable energy 확보, but they can only be sustainable if agricultural productivity—the farmers’ main occupation—is maintained,” adding, “We will promptly establish and disseminate cultivation guidelines based on empirical data.”