The most efficient tilt for photovoltaic panels in Chicago, Illinois at a latitude of 41.84°:
Your photovoltaic panels need to be angled facing south.
If you're mounting the photovoltaic panels at a stationary angle, such as on your roof, the most efficient angle is 34.9°.
If you're planning to change the angle of your photovoltaic panels twice per year, the most efficient angle is 17.9° in summer months and 55.8° in winter months.
If you're planning to change the angle of your photovoltaic panels each season, the most efficient angle is 14.2° in summer months and 61.2° in winter months, and 38.7° in autumn and spring months.