I have asphalt shingles on my home that are 30 years old. I have no leaks - just some moss/mildew on the current shingles as I live in a moist environment (Hawaii). I am considering putting solar panels on the roof and have been advised to re-roof beforehand due to the roof's age.
The roofer I consulted advised me that I could save money by simply covering the existing shingles with a layer of new asphalt shingles. Is this advisable? What do you suggest?