Recently John Matarese did some research on the Suburban Mystery of melted siding! When the sun shines off yours or your neighbor’s windows, the light is magnified onto your siding, causing the melting. We have helped several customers with this same issue by installing window film on the exterior of the window.

See the article here: http://www.wcpo.com/money/consumer/dont-waste-your-money/suburban-mystery-melting-vinyl-siding