Aims Annual plants make up a large proportion of diversity in desert communities and are highly sensitive to changes in microclimate. The rapid development of utility-scale solar energy facilities throughout desert regions alters the local distribution of precipitation and shading, but the consequences for annual plant community composition and diversity are largely unknown. We evaluated the influence of single-axis tracking photovoltaic panels, and the microclimates they create, on annual plant communities in a utility-scale facility constructed with methods to minimize disturbance across three different vegetation-soil types.Location The study was conducted in the eastern Mojave Desert, Nevada, USA.Methods We used 1-m2 quadrats to sample annual plant density and diversity in 30 areas within the facility and 30 control areas outside the facility for each of three soil types characterized by distinct perennial vegetation. Each sampling area within the facility included three solar panel microsite categories: under panels, panel driplines, and between panels (interspace), which were compared to controls.Results We found that the effect of the microsites on native annual plant density and diversity depended on the vegetation-soil type. Solar panels increased native annual plant density and diversity in deep sandy soils but decreased density and diversity in shallow sandy soils. Annual plant diversity was higher in solar panel driplines compared to other microsites in a silty soil with low perennial cover. Microsite changes in shallow soil moisture resulted in differences in the annual plant community in deep soils, while soil surface temperature was a major influence in the shallow soil annual plant community.Conclusions Our results suggest that native annual plant diversity can increase with more heterogeneity in microclimate conditions created by low-impact photovoltaic facilities in arid settings, but effects depend on the underlying vegetation-soil type.