Solar is planned for my house, but then I have lots of sun here. Cost per kilowatt is currently north of 16 cents. It is not coming down anytime soon.
Going green means putting more money in someone else's pocket. With the power company having to buy back power from the customer who makes more than they use is moving the money pocket. At least that is the current situation here. They have challenged the buy-back in the courts here but have lost each time so far, because they cost of buyback is less than the costs of new generation for them. That works as long as the demand continues to increase, and people keep coming here to live.
Where they get us is an availability charge, just as the water companies do. If it is available to your property, you get a bill whether you are hooked up or not. I see that cost increasing in the future. Infrastructure is expensive and shareholders expect a return on their investment. No relief from any of this.
As for cost of upkeep, much depends on changing technology, but I know people with solar units over 20 years old and still producing.
There is maintenance. With us it is keeping them clean in the dry season. Other areas have high wind situations or hail which presents a problem. Snow doesn't help either. No damage. Just no production until the snow is cleaned off!
I have a local friend who invested in solar for his house. His summer bill with A/C was ~$500/per month. Now he breaks even or even gets a credit during A/C months. He elects to take a check from the power company each quarter. I have been watching his experience with interest since he had it installed about 18 months ago. I haven't asked him about payback, but he originally calculated 7 1/2 years. After it was in for a few months, he recalculated to around 5 years. That may have changed again. I just don't know. Original investment was ~$25,000 for a 3,000+ sqft, 2 story house. Mine should be 1/3 of that.