What aforementioned assumed that you own your photovoltaic system, and do Not lease nor have it under a purchase agreement. As if you do not own the solar system, then you have to pay for it when the time comes to sell the house, but in that case you will lose much, because you will pay the whole price to the solar company early, and only the other option is to try convincing the buyer to take the contract with the solar company over. Mostly, the new house owner will agree to take the contract, but if not, then you will get in stuck.
The tariff will differ from one retailer to another, and for each retailer you have to study the advantages he offers and disadvantages as well, you have to weigh up all points, and then take decision in which retailer you will proceed with. Also, from time to time, you need to check the retails in your local area for any tariff changes that may occurs, as you may consider to change the retailer to get the best tariff.
Generally, the solar photovoltaic system with its different types (Grid Tie, Off Grid, and Hybrid) deal with risky voltages values, its alive electricity with voltages that can hurt and cause die to human in case of direct contact. Also, there are some technical areas that needs solar professionals to deal with, like the issues related to wind loading and how the solar system can withstand this safely, how to make voltage compatibility between solar panels configurations, and how to do installation and commission for the solar inverter. One more important thing is that in order to get solar rebates for the residential solar system from your government, your solar system must be installed by professional, licensed and accredited solar system installers.