Should I solarise my existing electric pump under PM-KUSUM Component C or get a new solar pump?

It depends on whether you already have a working grid connected pump. PM-KUSUM Component C is for solarising an existing grid connected pump: you keep your current pump and electricity connection and add solar, so you run on solar by day, can fall back on the grid, and in some models can feed surplus solar power back to the grid for an income. This suits farmers who already have a reliable grid pump and want to cut their power bill and earn from surplus. Component B is a standalone off grid solar pump, best for fields with no electricity connection or unreliable supply, where you want to be independent of the grid altogether. So if you have a good grid pump now, Component C lets you build on it; if you have no connection or poor supply, Component B gives you a fresh standalone system. The subsidy split, the grid feed in option and its rate, and which components are open in your state all vary and change over time, so do not assume the surplus sale or any feature is available everywhere. Confirm the current Component B and C details, eligibility, subsidy share, and empanelled vendors on your state PM-KUSUM portal before deciding.