A solar array will last at least 25 years. It’s important that the roof underneath it be in good shape. If your roof is more than 10 years old, you should have it evaluated to determine its remaining lifespan. You may want to consider repairs or replacement before installing solar. In some situations, work to improve the structural capacity of your roof to withstand a solar installation can be rolled into the federal tax credit. (Note: This only applies to structural upgrades, not re-roofing). IRS code is vague on the exact scope of roof work that can be rolled into the federal tax credit. We suggest you consult with a tax expert on the specifics of your roof.