Hi I work for a solar company here. So I can help you out a little bit. The big answer is, it depends. Not all solar is the same in every state. Here's a resource guide:
https://solarpowerrocks.com/pennsylvania/This will cover all the basics of solar and incentives in Pennsylvania. Not all utilities buy back power. In New York, they don't buy the power, they credit you for the generation in summer and you work off those credits in winter. It sounds like you have full 1 for 1 net metering in PA. That means your bill should balance out. Now by starting in Winter you will have both a power bill and a solar bill. That's because you don't have any solar credits.
If Solar City pitching you a lease deal or a ownership deal? There are three general methods of solar: Leasing, Power Purchasing, and Owning.
Leasing and PPAs are very similiar. Big picture, you don't own the panels, are back to square one after the terms are up, and only gain a slight initial savings compared to owning a system. They are also a pain in the ass to deal with when selling a home.
Owning means the system is yours. The payments are a flat rate. Eventually they go away. If all is planned well, your yearly payments should match your yearly utility payments the first year. You'll see small savings over time as utilities go up an average of 4% a year but that solar payment is the same. The real savings don't kick in until the system is paid off, 10-20 years depending on terms. At that point, a system will easily pay for itself in the next five years of savings.
Solar is about the long game if you want savings. The short term plans all sound good, but they don't pay off as much in the end.