Not only trees will help, but so will trellises and vines, and they tend to be quicker to do it. Site your trellises near, but not against, the walls (and roof, if possible), leaving a space between the two. Use strong trellises that will last, not those wimpy little things you see so often.

Find out what vining plants grow well there. Many are fruiting vines, and that would be an asset, too.

Maybe you could even sell the fruit to the neighbors to offset part of your electric bill...

Sue