Regular fabric maintenance generally means a once-a-year cleaning, with additional care if stains or soil age appears. The regular cleaning schedule starts the first year in which the awning is in service. To ensure longevity of fabric quality we highly recommend a regular regimen of brushing debris off the fabric (daily) and an occasional soapy wash (natural soaps are best) with a thorough fresh water rinse as needed. This care applies to 100% acrylic fiber awnings.

Soltis non-acrylic materials may be cleaned with liquid detergent and water. If you use a liquid detergent to clean your awning fabric, it is best to reapply a water repellent treatment, such as 303 Hi-Tech Fabric Guard or similar product.

Let fabrics completely air dry. Make sure to store your fabric in a dry, well-ventilated area. See below for help with various stains.

Fruit stain liquid detergent/ammonia, 3-6% water
Grease — automotive volatile solvent (acetone)
Iron rust oxalic or citric acid, water
Mildew 1/2 cup bleach and 1/4 cup natural soap per gallon of water
Oil solvent (acetone)
Paint — latex, wet liquid detergent and water
Paint — latex, dry paint/oil/grease remover
Paint — oil or lacquer paint/oil/grease remover
Tree sap turpentine, liquid detergent

I used Simple Green on my desert dust awning mess. Worked great.

Good post.
A little additional info from A&E on acrylic fabric awnings:

From a A&E pdf file:

Acrylic awnings have the color woven right into the fabric.
Acrylic also performs a little differently than vinyl in wet weather. It is water repellent,
not waterproof. Because it’s a woven cloth, it breathes. Air circulates through the fabric so dew and rain can dry quickly. However, you should avoid touching the underside of an
acrylic awning when it is wet. This will break the surface tension and allow seepage through the fabric. If your awning gets rolled up while wet, unroll it as soon as the weather allows. It should be completely dry before rolling it up again to avoid mildew.
To keep your acrylic awning clean, simply hose it off occasionally and let it dry. Do not scrub your acrylic awning as this could remove its water retardant finish. If you need to remove a grease spot, use K2R Spot Remover; this is different than how you would remove a similar spot from a vinyl awning.

From an email from A&E

We recommend to use mild detergent and warm water. A 1/2 cup of non chlorine bleach can be used. Once a fabric is cleaned, you may need to retreat with Scotchguard.

Great! Now you have given me one more maintenance item I can add to the list of those that are never going to get done.