What is the first step in the solar system application process for a home or office in India?

First of all be clear of the fact that the benefits of PM Surya Ghar is given only for residential properties and not for offices. In caee you want to install rooftop solar at your office, there will be no govt financial support. The first process usually is your application through National Rooftop Portal where you have fill all the details. Soon after you fill the details, the online file goes to the local discoms seeking Technical Feasibility Report (TFR). Usually the discoms grant TFR within 15 days. Only after getting the TFR, you can ask the vendors to install the rooftop solar. Even after installation, your need discom permissions and approvals to commission it.