Agrivoltaic systems offer a promising approach for dual land use, yet the findings published so far still present considerable variability due to the complexity and novelty of the field. Part of this divergence arises from the diverse configurations and methodologies employed across studies, underscoring the need for standardized evaluation criteria. This paper presents a critical overview on the types of systems used for experimental research in agrivoltaics, including variables measured, their co-occurrence and interconnectivity, agricultural activity and application. A systematic literature review was performed using the Scopus database to identify key considerations for measurement campaigns, minimizing inconsistencies and enhancing the reliability of findings. After applying screening criteria to 637 articles, 78 were classified as field experiments and further analyzed in terms of the measured variables, employed methods, and performance metrics. The paper identifies key research gaps not yet addresses in depth in experimental research. Initial findings reinforce a geographic bias, with most studies concentrated in temperate regions, while tropical and semi-arid areas remain underrepresented. The most studied agrivoltaic systems variables focus on microclimate and productivity, including air temperature, air humidity, soil moisture, evapotranspiration, biomass, and energy output, while key research gaps persist in carbon balance (soil carbon stocks and greenhouse gas emissions), soil health (i.e., soil chemical, physical and biological indicators), plant quality, and long-term ecosystem impacts. Moreover, electricity production gains due to cooler environments remain uncertain, still requiring a systematic approach to assess it.