1 3-1-1 for carry-ons = 3.4 ounce (100ml) bottle or less (by volume) ; 1 quart-sized, clear, plastic, zip-top bag; 1 bag per passenger placed in screening bin. 2  One-quart bag per person limits the total liquid volume each traveler can bring. 3.4 ounce (100ml) container size is a security measure. 3  Be prepared.
Variable costs. A solar power plant is one of the cheapest to operate because there are no fuel costs involved. A solar PV (photovoltaic) power plant requires fixed expenses of $11.40 per megawatt hour, or just 1.14 cents per unit. Whatâs more, it doesnât require any variable expenses.
The thing to remember, however, is that 100 watts per hour purchased from the power grid would only cost about 24 cents a day right now, or $91 a year. That's why you don't see many solar houses unless they are in very remote locations. When it only costs about $100 a year to purchase power from the grid, it is hard to justify spending thousands of dollars on a solar system. Â­