Commercial solar panels MNWhile traditional thinking will have most people uncomfortable with any major project with a return on investment (ROI) of more than 2-3 years, solar offers a unique investment that should fall outside of the traditional thinking. First, it is offsetting a portion of your home's or business's electric bill, in which history has proven to have an annual increase regionally at a rate of 6-12%. Thus, interest saved is interest gained. It is no different than financing a home or similar, versus just paying for it outright, as financing adds more dollars on top of that item, sometimes doubling or even tripling that items' final cost.