Has anyone installed solar panels recently, and how long do you realistically expect the payback period to be?

Unless you are staying in semi D or mansion with large roof, with unblocked light (no high rise buildings around), it is not realistic to even install solar panel. Not to mention, the ROI takes a few years. So it is not realistic to even install one for most people.

Since it's for personal use, why worry about breaking even? It's not for commercial use, so there's no need to consider both usability and profitability. It's like buying a car to drive as a taxi; you have to calculate when you'll recoup your investment, the car's maintenance, and the driver's workload.