For this question, it is difficult to give a totally right question. The best angle for solar panels are depended on too many factors, just like where you are and how is the weather? In Summer the angle can be calculated by subtracting 15° from the location latitude and in the Winter by adding 15° to the latitude. Seasonal angle adjustment can increase annual power output by up to 15%.
Solar panel output is affected by several variables, some we can adjust and others are decided by our location and environment.
One way to make sure you’re optimizing the power output of a 450 watt solar panel array is to adjust the tilt angle. Solar batteries are most efficient when the sun’s rays are perpendicular (90°) to the panel surface.
The optimum tilt angle will vary according to location and the effect on solar output will be variable according to the irradiation level at your geophysical location.
Contrary to popular belief, power output due to tilt angle isn’t caused by the structure of the solar cells, but simply the fact that the sun’s energy is spread over a greater area when the angle is oblique.
If the sun’s rays cover 1 square meter of the panel surface at 90°, then the same sun’s energy will be spread over 1.5 square meter if the panels is tilted at an angle of 45°.
There really is no minimum angle for solar panel tilt. The fact is that they will still work even at 0° or at 90°. Solar panels mounted on a flat roof would be at 0°, while panels mounted on the side of a building would be at 90°.
The reduction in power output isn’t linear according to the tilt angle, because the combination of reflection and indirect sunlight generates power as well.
The amount of tilt angle recommended for your solar panel array depends on your geophysical location, but it’s a bit more complicated than that!
The table below shows the difference in the sun’s energy falling onto a flat panel surface compared to a panel mounted at a tilt angle of 50° in Denver Colorado.
In Denver, the amount of sun’s energy falling onto a flat solar panel is almost 50% of that irradiating a panel mounted at 50°. That’s quite a reduction.
However, in high summer, the amount of energy falling onto the flat mounted panels is more than the tilted panel. This means that the annual irradiance should be taken into account before deciding on tilt angle.
Although irradiance is measured in direct radiation, the combination of diffused and reflected sunlight ensures that the energy generated on solar panels mounted flat is not a lot less than when at an angle.
The table below gives the average estimated reduction in output power for a solar panel array at various tilt angles in Northern and Southern USA.
Note: There will also be considerable variation from East to West. For this reason it’s best to get accurate estimates from solar professionals for your exact location and orientation.
While it is possible to add an automatic motorized system to move the solar panels so that they are always perpendicular to the sun’s rays, such systems are expensive. (Sun tracking.)
It may be more cost-effective to set the solar panels angle on a movable frame and adjust the tilt angle just twice a year, summer and winter.
This would entail going up on the roof and physically changing the tilt angle, but what is the best tilt angle for you solar panel array to optimize power output?
In the Northen hemisphere due south is perfect, but if this can’t be achieved, any variation South combined with East/West will be OK.
Irradiation comes not only directly, but also in a diffused form caused by reflection from particles in the atmosphere. This means that there is always indirect sunlight to generate some solar power.
Modern solar systems tend to have microinverters mounted per panel, or for a group of panels.
Microinverters can optimize power output of solar panel arrays with different orientations so that differences in output of one array doesn’t reduce the whole system output.
The only direction to avoid if at all possible is due North, which means the solar panels would never see direct sunlight – not ideal!