Light Requirements & Shade Cloth

[Roberta]

Consider Aluminet (made from aluminized Mylar). It provides even shade, and also reflects heat as well as light away from the growing area - I find it noticeably cooler under the Aluminet than adjoining "regular" shade cloth. And it even helps a bit in winter, reflecting ground heat back to the plants.

[estación seca]

The percent shade is measured with light incidence perpendicular to the cloth, or 90 degrees from the plane of the cloth.

If the cloth is tilted 90 degrees such that the rays hit it edge-on it will allow 0% of the light through. The area shaded will be very tiny. It's hard to keep it always in that orientation, however, since the sun appears to move around in the sky.

At angles between 0 and 90 degrees the cloth provides more shade than the stated rating, and the amount is proportional to the degree of inclination from perpendicular. But the sun appears to move around in the sky, so the amount of shade provided varies slightly through the day, no matter how the cloth is positioned.

It will be less not more shady if the cloth is angled away from perpendicular, but 45 degrees won't make much difference to your plants.

Finally, you're overthinking things. Roberta's location is similar to yours. Try what she suggested.

[Ray]

At any angle other than 90-degrees, the shade cloth with block more sunlight, due to the thickness of the web occluding the openings. However, as they are relatively thin, it won’t be much.

Think of vertical window blinds as an example of a very thick shade cloth. From straight on, you can clearly see through it, but as you move to the side, the observable gaps get smaller and smaller, with the slats eventually completely blocking your view.