Window cleaning is definately a different skill set than power washing, we own and operate both a window cleaning and a power washing business. They both require different tools, skill sets, and soaps. I would not recomend using your wash solution that you use on buildings, it will not have the water softeners in it that window cleaning solution has. You will want to get the proper equipment and supplies for washing windows, this is different than power washing equipment. Do not power wash windows, the seals are not designed to withstand more than about 15 lbs. of pressure. You could benefit from buying a video or book on how to wash windows professionally. You can find these @ ABC window cleaning supply (google it).