Agrivoltaic Systems — Crop-Yield and Power Generation Balance Design Based on Real Data

Evidence-Based Design Guide | Paddy (畓) · Upland Field (田) · Pasture (牧) — Optimal kW per Acreage

Why Design Matters

Installing solar panels above farmland is straightforward. Finding the balance where crop yields are maintained and power revenue is maximized is an entirely different challenge. Over-sizing capacity raises the shading ratio, cuts crop yields, and ultimately compromises both agricultural and generation income.

The core principle confirmed in real-world data is this: only the surplus solar irradiance exceeding a crop’s light-saturation point should be converted to electricity. Shade beyond that point damages photosynthesis. Analysis of 62 domestic agrivoltaic demonstration sites (2022) by the Korea Rural Economic Institute confirmed that when the shading ratio exceeds 30%, yield loss in most crops crosses the critical threshold.

Universal Design Standards (Applicable to All Land Types)

Before site-specific design, the following legal and structural requirements must be met for any agricultural land type.

Item	Standard
Structure Height	≥ 3 m (agricultural machinery clearance)
Column Spacing	≥ 4 m (tractor, combine harvester access)
Max. Shading Ratio	≤ 30% (photosynthesis maintenance)
Eligible Land	Outside Agricultural Promotion Zones / Agricultural Protection Zones (temporary use permit)
Permit Duration	Max. 8 yrs + 3 yr extensions (up to 30 yrs under 2026 new legislation)
Capacity Cap	< 500 kW (KNREC loan eligibility)
Yield-Loss Limit	≤ 20% recommended (National Assembly Research Service)

A structure height of 3.5–4 m is the practical recommendation. The 3 m figure is the legal minimum; spray equipment typically requires 4 m of clearance.

Area-to-Capacity Conversion Reference

Land Area	Approx. (㎡)	Recommended Capacity	Notes
300 pyeong (~990 ㎡)	~990 ㎡	30–50 kW	Entry-level small farm
500 pyeong (~1,650 ㎡)	~1,650 ㎡	50–80 kW	Optimal KNREC loan bracket
1,000 pyeong (~3,300 ㎡)	~3,300 ㎡	100–150 kW	Standard commercial unit
2,000 pyeong (~6,600 ㎡)	~6,600 ㎡	200–300 kW	Cooperative/corporate scale
≥ 3,000 pyeong (~9,900 ㎡)	~9,900 ㎡	300–500 kW	Must stay below 500 kW cap

KNREC demonstration benchmark: 99 kW on 2,000 ㎡ (~605 pyeong) generates approximately 114,000–120,000 kWh/year. Agrivoltaic installation requires approximately 6–7 pyeong per kW (versus 2–3 pyeong for standard ground-mount).

Paddy Fields (畓) — Rice-Centered Design

Crop Characteristics and Shade Tolerance

Rice has a light-saturation point of approximately 50,000–70,000 lux. Since Korean summer irradiance routinely exceeds 80,000–100,000 lux, a shading ratio of 20–25% does not materially impair photosynthesis. Domestic demonstration results:

Tracking (adjustable) systems: average yield 81% of baseline (19% reduction)
Fixed systems: average yield 82% of baseline (18% reduction)
Tracking: every 10% increase in shading → ~31 kg/unit yield decrease

Planting density adjustments can partially offset yield losses.

Paddy — Area-Based Design Table

Paddy Area	Recommended Capacity	System Type	Est. Annual Generation	Est. Annual Revenue (×185 KRW/kWh)
300 pyeong	30 kW	Fixed	~36,000 kWh	~6.66M KRW
500 pyeong	50 kW	Fixed	~60,000 kWh	~11.1M KRW
700 pyeong	100 kW	Fixed/Tracking	~120,000 kWh	~22.2M KRW
1,000 pyeong	100–150 kW	Tracking preferred	~132,000–156,000 kWh	~24.4–28.9M KRW
≥ 2,000 pyeong	200–300 kW	Tracking	~240,000–324,000 kWh	~44.4–59.9M KRW

Revenue rate: SMP + REC combined ~185 KRW/kWh (Yeongam 2025 demonstration rate)

Real Case: Yeongam, Jeollanam-do (2025)

In the 2025 Yeongam demonstration project combining rice cultivation and solar generation, total annual revenue was estimated at ~9.89 million KRW. Rice yield fell by ~21%, but solar revenue (~8.97M KRW) more than offset the loss, yielding 8.4× the revenue of rice farming alone.

In Boseong, Jeollanam-do (Korea’s first farmer-led agrivoltaic project, 2020), annual net income reached approximately 14.4 million KRW (13.0M from power + 1.4M from rice).

Key Design Considerations for Paddies

Column foundations must not disrupt irrigation flow. Concrete footings should be placed on field boundaries or separate base platforms. Concentrated runoff (rainfall channeling from panel edges) is a documented cause of localized crop damage — drainage design must accompany structural design.

Upland Fields (田) — Horticulture and Specialty Crops

Crop Shade Tolerance Classification

Crop selection determines design more than any other variable.

Suitable crops (yield loss ≤ 20%)

Crop	Yield Change	Notes
Potato	~10% decrease	Heat stress reduction effect
Cabbage	Potential increase	Significant summer shading benefit
Green onion (jjokpa)	Minimal impact	Semi-shade preference
Perilla	Minimal impact	High shade tolerance
Sweet potato	Maintained	Long growing season, adaptive
Sesame	No impact	Confirmed in Goesan demonstration
Ginseng	Favorable	Traditionally shade-cultivated
Green tea	+29.8% yield increase	Relieves summer photoinhibition

Higher-risk crops (yield loss > 20%)

Crop	Yield Change	Note
Garlic	~21.5% decrease	Underground crop, light-sensitive
Onion	~16.0% decrease	Near tolerance limit
Cabbage (napa)	~15.1% decrease	High seasonal variability

The Jeju Western Agricultural Technology Center demonstration (40 kW, 750 ㎡, 26.8% shading) confirmed garlic and onion yield declines but cabbage yield increase. Crop selection precedes capacity design.

Upland Field Design Tables

Shade-tolerant / semi-shade crops (shading ratio 25–30% allowed)

Field Area	Recommended Capacity	Est. Annual Generation	Est. Revenue
300 pyeong	40–50 kW	~48,000–60,000 kWh	~8.9–11.1M KRW
500 pyeong	70–100 kW	~84,000–120,000 kWh	~15.5–22.2M KRW
1,000 pyeong	150–200 kW	~180,000–240,000 kWh	~33.3–44.4M KRW
≥ 2,000 pyeong	300–400 kW	~324,000–432,000 kWh	~59.9–79.9M KRW

Sun-demanding crops (shading ratio must be held to 15–20%)

Field Area	Recommended Capacity	Rationale
300 pyeong	20–30 kW	Fewer panels to limit shading
500 pyeong	40–50 kW	Wider spacing + tracking required
1,000 pyeong	80–100 kW	Crop protection over generation

For garlic or onion farmers interested in agrivoltaics, crop transition to shade-tolerant species is the most practical path before committing to system design.

Field-Specific Design Notes

Upland machinery (bed formers, cultivators, plastic mulchers) is often narrower than paddy equipment, but column spacing should still be ≥ 5 m for operational comfort. Wider spacing reduces installable kW per area — account for this in capacity estimates.

Pasture / Grassland (牧) — Forage Crop and Livestock Design

Why Pasture Suits Agrivoltaics

Pastureland offers the most forgiving shade tolerance among the three land types. European agrivoltaic research consistently shows that panels over pasture reduce summer evapotranspiration and relieve heat and drought stress on grass, sometimes increasing biomass. The key: panel height must accommodate crop canopy.

Pasture crop shade tolerance

Forage Crop	Allowable Shading Ratio	Notes
Italian ryegrass	Up to 30–35%	High tolerance
Forage maize / sorghum	≤ 20%	Tall crops need ≥ 4 m structure height
Kentucky bluegrass, orchardgrass	Up to 25–30%	Standard pasture mix

Pasture — Area-Based Design Table

Pasture Area	Recommended Capacity	Structural Notes	Est. Annual Generation	Est. Revenue
500 pyeong	50–70 kW	Column spacing ≥ 5 m	~60,000–84,000 kWh	~11.1–15.5M KRW
1,000 pyeong	100–150 kW	Height ≥ 4 m mandatory	~120,000–180,000 kWh	~22.2–33.3M KRW
2,000 pyeong	200–250 kW	Tracking system recommended	~240,000–300,000 kWh	~44.4–55.5M KRW
≥ 3,000 pyeong	350–500 kW	Clustered layout preferred	~420,000–540,000 kWh	~77.7–99.9M KRW

Livestock Co-benefits

Livestock naturally seek shade under panels in summer, providing an animal welfare benefit. However, cattle rubbing or pushing against columns is a real operational concern. Lower-column protective guards are mandatory.

Profitability Comparison — 1,000 Pyeong Benchmark

Land Type	Crop	Capacity	Est. Agri Income	Est. Solar Revenue	Total	vs. Farming Alone
Paddy (畓)	Rice	100 kW	~2M KRW	~22.2M KRW	~24.2M KRW	~10×
Field (田)	Perilla / green onion	150 kW	~5M KRW	~33.3M KRW	~38.3M KRW	~5–6×
Field (田)	Ginseng	80 kW	~20M KRW	~17.8M KRW	~37.8M KRW	~1.5×
Pasture (牧)	Italian ryegrass	150 kW	~3M KRW	~33.3M KRW	~36.3M KRW	~8×

Pre-loan-repayment revenue figures. 100 kW installation cost ~150–200M KRW; 70–90% financing available through KNREC. 20-year operation B/C ratio = 1.24; income 2.63–2.8× rice farming alone (KREI analysis).

Design Decision Flow

1. Confirm land cadastral type → Paddy / Upland Field / Pasture
2. Identify current crop's light-saturation point
3. Assess whether yield loss will stay ≤ 20%
 └ If > 20% risk → switch crops or constrain shading to ≤ 15%
4. Measure exact area → estimate capacity at 6–7 pyeong/kW
5. Set structure height and column spacing (min. 3 m / 4 m; recommended 4 m / 5 m)
6. Confirm shading ratio ≤ 30%
7. Finalize capacity within < 500 kW limit
8. Apply for temporary agricultural land use permit + power business license

References

Korea Rural Economic Institute (KREI). (2023). Economic Analysis of Agrivoltaic Adoption and Policy Implications. Report P293.
Rural Development Administration / Nongsaro. (2023). Agrivoltaic Under-Panel Environment and Rice Yield Changes.
Green Energy Research Institute. (2023). Agrivoltaic Demonstration Site Survey: 62 Sites.
Yeongam County, Jeollanam-do. (2025). Agrivoltaic Rice-Power Co-production Demonstration Results.
Boseong, Jeollanam-do. (2020). Korea’s First Farmer-Led Agrivoltaic Project Operations.
Jeju Western Agricultural Technology Center. (2023). Agrivoltaic Suitability for Brassica Crops.
Korea New and Renewable Energy Center (KNREC). (2024). Rural Solar Support Program Standards. (knrec.or.kr)
National Assembly Research Service. (2024). Agrivoltaic Yield-Loss ≤ 20% Recommendation Basis.
RE:FACT. (May 2026). Agrivoltaic Economic Viability Fact-Check Report.
Journal of the Korean Solar Energy Society. (2021). Design Considerations for Agrivoltaic Systems Considering Upper and Lower Irradiance.
Act on Promotion and Support of Agrivoltaic Power Generation Business (passed National Assembly May 7, 2026).
Goetzberger, A. & Zastrow, A. (1981). On the coexistence of solar-energy conversion and plant cultivation. International Journal of Solar Energy, 1(1), 55–69.