The most efficient tilt for photovoltaic panels in Baltimore, Maryland at a latitude of 39.31°:
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 33°.
If you're planning to change the angle of your photovoltaic panels twice per year, the most efficient angle is 15.6° in summer months and 53.6° in winter months.
If you're planning to change the angle of your photovoltaic panels each season, the most efficient angle is 11.9° in summer months and 59° in winter months, and 36.2° in autumn and spring months.