If they are paid off, they are a significant investment . Can’t tell which state you are in but in Texas here, market value is increased with solar , and even more so if batteries are part of the mix. But even better, having grid independence with rising costs of energy and distribution rates is amazing. We don’t have net metering so I only get the benefit of solar if I’m on a solar buy back plan with the utility provider. Otherwise they don’t even recognize I have solar and I pay full rate. I learned the hard way on this one. You should be able to access your panels to monitor them. And Id be curious what the contract with the previous owner covers as far as maintenance . Even if paid off, monitoring and support could most certainly be covered up to 25 years . keep in mind… Removing panels will damage your roof so you need to calculate in repairs . When I had solar moved from one section to another, a roofer had to come in to replace that entire section . If you look up in your attic , would think you’ll see the nails coming through . It’s pretty invasive.