Mahamadou Hamidine^1,, Aminou Baare Ali^{2, 3}, Harouna Sani Dan Nomao⁴, Makinta Boukar^{2, 3}, Saîdou Madougou^{2, 3}

In Sahelian field conditions, solar irradiance, temperature, wind, and mounting configuration vary together and can complicate the interpretation of photovoltaic measurements. This study examined relationships among wind speed, solar irradiance, module inclination, and open-circuit voltage (V_oc) for two identical 20 W monocrystalline silicon modules installed in Dosso, Niger. One module was horizontal; the other inclined at 15°, with both facing south. Measurements were recorded hourly from 07:00 to 18:00 in May and August 2021. Hourly Pearson and Spearman coefficients were treated as descriptive measures because the 12 clock-hour means are serially ordered and share a common diurnal cycle. Exploratory three-predictor regressions, multicollinearity diagnostics, and a daily sensitivity analysis for both module configurations were also applied. Hourly Pearson correlations between wind speed and V_oc were 0.846 and 0.833 in May and 0.801 and 0.808 in August for the horizontal and inclined modules, respectively. Corresponding irradiance correlations were 0.711 and 0.889 in May and 0.848 and 0.896 in August. The exploratory models explained 77.6–85.0% of hourly V_oc variation in May and 73.9–80.5% in August. However, coefficient confidence intervals were wide, and variance inflation factors indicated substantial predictor collinearity, particularly between wind speed and irradiance in August. Daily wind–V_oc associations were much weaker for both modules. The measurements therefore support a multivariable interpretation of outdoor V_oc variation; they do not directly demonstrate wind-induced cooling because module temperature, local module-surface airflow, and wind direction were not measured.

photovoltaic module, open-circuit voltage, wind speed, solar irradiance, module inclination, Sahelian climate