Computerworld - You may have noticed lately that more residences and businesses are being equipped with photovoltaic solar roof panels. The reason is relatively simple: the cost to do so has dropped dramatically over the past five years.

The cost of installing photovoltaic solar arrays has dropped to $3 per watt of electricity they produce - about the same as coal-powered plants cost to build - creating a watershed moment in the development of clean energy, experts say.

The average price of a solar panel has declined by 60% since the beginning of 2011, according to GTM Research. And, according to CleanTechnica, a website dedicated to renewable energy news, the price of solar power has fallen rom $76.67 per watt in 1977 to 74 cents today.

This year, solar power was the second leading source of new electricity,according to CleanTechnica.

The amount of power produced by solar arrays in the U.S. is skyrocketing as installations soar. This year, it's expected that the amount of power solar arrays produce will be equal to that of 10 nuclear power plants or 10 gigawatts (a GW is equal to 1 billion watts), according to GTM.

As a whole, the U.S. installed 4.3GW of PV solar arrays this year, a 27% increase over 2012.

Average installed PV price per market segment from Q3 2011 through Q3 2013 (source: GTM Research).

Solar array installations reached 930 megawatts (million watts) in the third quarter of 2013, up 20% over the previous quarter; that represents the second-largest quarter for solar installations in U.S. history, according to GTM. This year, the U.S. is expected to surpass Germany in solar installations for the first time in more than 15 years.

One of the reasons for the huge drop in price has been a massive ramp up of PV manufacturing around the world over past five years,; that includes China, which has become the biggest supplier of PV modules.

Another reason for the drop in price and uptick in installations is that during the 2008-2009 recession PV purchases slowed, creating an overcapacity of PV modules. Solar cell manufacturers began selling off their inventory at reduced prices and profit margins, according to Tom Leyden, CEO of Solar Grid Storage in Princeton, N.J.

Solar Grid Storage develops battery storage systems for PV arrays that allows power to remain on at night or as a backup source should electrical outages occur. "It's a really exiting time in the industry. We're one to two years from a massive explosion in solar power," Leyden said.

Another reason for the surge in PV installations is better financing from banks that have come to realize the relatively low risk in funding solar power projects.

How low is the risk? Earlier this year, Warren Buffet's electric utility, MidAmerican Energy Holdings, acquired a 579-megawatt solar development project in Southern California for about $2 billion.

Other big corporate investors in solar include Intel, Google and Apple. High-tech companies are all making significant investments in renewable energy, not only for the green effect they will have, but the cost savings.

For example, just last month, Google announced the latest in a series of ongoing investments in solar power; the company will build six new solar plants to the tune of $80 million. To date, Google has committed more than $1 billion to wind and solar power plants that create clean energy and generate "attractive financial returns," the company stated in a recent blog post.

U.S. PV installation forecast from 2010 through 2016 (Source: GTM Research).

Businesses are just one segment of the solar power industry. Residential installations are also booming. GTM forecasts that by year's end, residential solar installations will have hit a 52% growth rate over last year.

"As we approach the end of 2013, it remains clear that this will be a banner year for solar in the United States," a joint report by GTM and the Solar Energy Industry Association stated. "By the end of the year, more than 400,000 individual solar projects will be operating across the country."