Test Window electric output and daily energy monitoring results. (a) Instantaneous PV voltage variations (at MPPT, as monitored in real time by Victron 75/10 Charge Controller during morning hours); (b) an example I–V curve of a solar window with a low-quality interlayer measured with PROVA 200A PV Module Analyzer at close to optimum window orientation, featuring a distorted I–V curve shape with side-peaks in the power-voltage curve; the output electric parameters also illustrate the significant reduction in the fill factor (FF) from its expected value of near 0.76; (c) daily energy output of Test Window measured by Victron 75/10, monitoring done for 21 days; data are plotted against the measured (per-window average) energy outputs of other solar windows installed in nearby wall arrays, and the wall average measured from 30 windows (arrays J, F, and C); (d) measured intra-day electric power output traces.