How many panels required to produce appx 350 units of electricity per month

Typically in Indian conditions, you can expect panels equivalent to 1kW  to generate between 4-5 units per day on average, when taken for the full year. There are periods when generation will be much higher, like the February to June period. Similarly, in North India, generation during November to January end would be much lower due to pollution, shorter days. In the early summer phase and summers, with clear skies, for every  kW capacity, you can get over 5, even 6 units in a day.

To answer your question then, if you go with the new mono panels available today, they would typically be in the 540 Watt range, You would thus need about 6 of those to be sure of getting 350 units per month on average, or 4200 units annually. Bifacial panels will deliver even higher output, at a higher initial cost of course.