That's an excellent question, as sun exposure is a major concern for anything left outside. The good news is that most modern plastic outdoor trash bins are specifically engineered to withstand UV rays, but their longevity depends heavily on the materials and additives used.
Standard, low-density polyethylene bins without protection will indeed fade, become brittle, and crack relatively quickly under constant sunlight. However, high-quality bins are manufactured with UV-inhibiting stabilizers compounded directly into the plastic resin. This additive acts like a sunscreen, absorbing and dissipating the UV radiation before it can break down the polymer chains.
You can expect a well-made, UV-protected plastic bin to maintain its structural integrity and color for many years. While some very slight fading over a long period is possible, it should not be the rapid, severe deterioration seen in unprotected plastics. The color is often permeated throughout the material, so fading is less noticeable than a surface coat of paint that chips away.
To ensure you're getting a durable product, look for bins marketed as "UV-resistant" or "all-weather." Darker colors like forest green, black, or brown may show fading less than lighter shades. Placing the bin in a partially shaded area can also significantly extend its lifespan and appearance. With proper selection, your outdoor trash bin should remain functional and look good for a long time.