The most efficient tilt for photovoltaic panels in Irvine, California at a latitude of 33.68°:
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 28.7°.
If you're planning to change the angle of your photovoltaic panels twice per year, the most efficient angle is 10.3° in summer months and 48.7° in winter months.
If you're planning to change the angle of your photovoltaic panels each season, the most efficient angle is 6.7° in summer months and 54° in winter months, and 30.7° in autumn and spring months.