50MW is 50,000 units per hour , 12,00,000 units per day. The avg plant load factor is 18% for a solar power plant so the total number of units produced is 2,16,000 units if each unit costs Rs 5 then in 1yr income is 35cr considering 330 days where 30 days is for maintainance or rains where no electricity is produced. For 10yrs revenue is Rs 350cr. The avg cost of installation of 1MW solar plant is about Rs 4cr or 200cr. Expenditure of staff, intrest, depreciation, maintainance expenses, and rate of return on equity @16% on capital employed, will all make the return on plant to be 20- 25yrs which is the plant life or solar module life of 25yrs. Any solar plant is given a 25yr contract for power purchase be it NTPC or National Solar power corporation.