Brad kicks off a solo episode (recorded before a trip to Germany) and turns the mic to rangeland scientist Anna Clare for a deep dive into “the solar savanna”—treating solar arrays on grasslands as functioning grazing ecosystems. She shares early results from Silicon Ranch’s Cattle Tracker research on integrating cattle (not just sheep) with PV systems. Brad follows with University of Minnesota’s on-farm demos: panel heights that work for cattle, heat-stress reductions, forage performance under panels, and a mobile, battery-equipped shade/solar rig. If you’re curious how and when cattle can safely graze under solar, this one’s packed with data and practical design tips.
Key takeaways
- Solar as savanna: Think of arrays as shade “canopies” over grasslands—manage them as grazing systems with soils, roots, pollinators, and large herbivores in mind.
- Cattle can work under PV: Moving from sheep to cattle is feasible when arrays are designed with animal size/behavior in mind.
- Panel height matters: In controlled mockups, animal interactions dropped 43% from 2.0→2.5 m and 59% at 3.0 m. Cattle never touched panels; most curiosity was with dampers—a design hotspot.
- Ecosystem wins: Under-panel zones showed higher soil moisture and lower soil temperatures, favoring cool-season grasses and legumes; regrowth dynamics can improve after grazing passes.
- Animal welfare benefits: UMN trials showed lower respiration rates and 0.5–1.0 °F lower internal body temperatures during hot afternoons for shaded cows—meaningfully less heat stress.
- Forage production holds up (or improves): Certain mixes (e.g., orchardgrass, meadow fescue; grass-legume combos) produced equal or greater biomass under panels with no drop in nutritive value.
- Design for cattle, not fear: After a decade of on-farm experience, Brad’s team hasn’t seen cattle damage panels; people and tractors are more likely risks than cows.
- Practical layouts: Keep inverters outside fences, route wiring high/inside racking, and allow equipment lanes; rotational grazing and (potentially) virtual fencing fit well.
- Innovation on wheels: A 20 kW mobile bifacial shade rig with onboard batteries can power irrigation, fencing, and even an electric tractor—bringing agrivoltaics to wherever cattle need relief.
Research & projects mentioned
- Silicon Ranch – Cattle Tracker: multi-year cattle-PV integration study; Phase 2 is a 4.5 MW Tennessee “outdoor test lab” comparing array vs. open pasture for behavior, space use, health/performance, plus mirrored ecosystem monitoring.
- Comprehensive literature review (AGU Earth’s Future – in press): Maps intersections among livestock–solar–land, identifies six research gaps (integration, layered ecology, modeling, best practices, social dimensions, collaborative science).
- UMN Morris agrivoltaics demos: Fixed-tilt arrays at 6–8 ft (1.8–2.4 m) leading edge; 0.5 MW pasture array powering campus; vertical bifacial and crop-under-PV pilots coming; EV fast charger powered by cow-shade solar.
Who it’s for
Developers, ranchers, extension pros, and policy folks exploring dual-use solar that keeps grasslands working and cattle comfortable.
Questions, comments, scathing rebuttals? -> themoosroom@umn.edu or call 612-624-3610 and leave us a message!
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