Arizona surges ahead with new $1B solar plant

I like this plan, but I just did some quick math.

Source: http://209.85.173.132/search?q=cache:jhpcqZRwpl0J:www.eia.do...

The average monthly electric bill in AZ is about $110.

60,000 households X $110 per month is 6,600,000. Per year that's 79,200,000.

One billion / 79,200,000 = 12.6.

Add the cost of 100 employees per year and it's about 14 years before the plant breaks even.

Is this usual for a power plant?