50 kWh's per day from a photovoltaic array.
If the prospective site for this array will see the equivalent of 4 hours of full rated power per day, as averaged out over the four seasons of one year and, this PV array is a flat plate collector angled at latitude all year... Then it will take a PV array of, at least 12,500 watts or 12.5 kW respectively.
Even if you could obtain this at $3.00 per watt that would amount to $37,500.00 not installed.
If you were to purchase this from the utilities at the going rate of $0.12 per kWh, that would amount to $6.00 a day or $2,190.00 per year. So, $37,500.00 divided by $2,190.00 would equate to a payback period of 171 years. Remember, that was not installed and your kWh's may vary. To the best of my knowledge PV modules are only warrantied for 25 years.
Potentially, a PV array of this size would be best located in a region of a continent that sees a high average amount of sunlight year round, as well as an area that sees unobstructed sunlight from the earliest sunrise to latest sunset as well as being installed as a pole mounted solar tracker "orchard." Not to mention that, the power made would have to negate the expenditure. In otherwords, be profitable. But thats just my opinion. For all I know, you could be planning to power a small community with all this power. There are so many variables and, you weren't very specific.
http://www.energy.gov/