At least with Solar City, installation and 30 years of maintenance are included in the cost of the system.
There is not really much to maintain in a standard residential solar installation as there are no moving parts. Except for the panels. They need to be kept clear of debris, dust, shade, snow (depending on geography).
It is my understanding that SolarCity does NOT maintain the surfaces. They will let you know of current degradation or fluctuations but it's up to you to debug / clear the problem.
In places with non-optimal solar climate I imagine that clearing the snow will be a pretty labor intensive job?