Tesla powers a whole island with solar to show off its energy chops, page-4

Summary: 1 kW of solar panels require approximately 100 sqft, or 10 sqm., when used on rooftops and in small ground mounted installations.
You might have heard that solar power plants require significant amounts of land to generate power. How much area indeed is required for solar power plants?

Solar power plants, be they on rooftops or on the ground, require significant area. While solar power has some critical sustainability advantages over fossil-based thermal power (coal or natural gas based), one of the key drawbacks of solar is that it recovers energy from a relatively diffuse energy source, sunlight. A 100 MW thermal power plant for instance would require less than 10% of the total area that a 100 MW solar PV power plant would.

Solar power plants require significantly larger land areas compared to conventional power plants. A 100 MW thermal power plant for instance would require less than 10% of the total area that a 100 MW solar PV power plant would.

How much area is indeed required for solar power plants?
That depends on the amount of kW of MW you would like to accommodate.
A simple rule of thumb is to take 100 sqft for every 1kW of solar panels.

Extrapolating this, a 1 MW solar PV power plant should require about 100000 sqft (about 2.5 acres, or 1 hectare). However, owing to the fact that large ground mounted solar PV farms require space for other accessories, the total land required for a 1 MW of solar PV power plant will be about 4 acres.

The above estimate is however for conventional solar PV power plants – those that are based on crystalline silicon and do not use trackers. A 1 MW of thin film solar plant will require about 30% more area than a similar power plant with crystalline solar modules.

So, keep the following in mind as simple thumb rules / benchmarks. A 1 MW solar PV power plant will require:

• 4 acres if it uses crystalline solar panels without trackers
• 6 acres if it uses thin film solar panels without trackers

http://www.suncyclopedia.com/en/area-required-for-solar-pv-power-plants/