We have never had much luck with 12 volt pumps, but we clean a LOT of roofs, often 3 or more in a day, and many are tile roofs. Air Compressor powered pumps are the only thing we have found to hold up. However, we have a larger air compressor of 18 cfm. Air pumps will work with less air, but they will not spray as well as they will with more air.
This is just my personal experiences, because I know plenty of roof cleaning friends who use 12 volt pumps,. with much success.
Bob from Pressure Tek stands behind all that he sells