Solar energy now costs the same as conventionally generated electricity in three European countries.

The latest report from an ongoing "PV (Photovoltaic) Grid Parity Monitor" study by consulting firm Eclareon found that the cost of solar- and fossil fuel-powered electricity has the same per kilowatt hour (kWh) price tag in Germany, Italy and Spain.

Germany decommissioned all of its nuclear power plants in 2012 after the Fukushima nuclear disaster in Japan.

The country has a ways to go to replace that with energy from renewable resources. While Germany is the world's top PV installer, with a solar PV capacity of 35.8 gW at the end of January, the total represents only 3% of its total energy produced there.

Germany has set a goal of producing 35% of electricity from renewable sources by 2020 and 100% by 2050.

In the U.S., there has been a 50% reduction in the cost of renewable energy over the past five years, according to an August 2013 report from global financial adviser and asset manager firm Lazard Freres & Co.

Price per kilowatt hour for energy in the U.S. (Source: OpenEI).

Cory Honeyman, a solar power analyst with GTM research, said the dropping costs of solar power has spurred utilities to sign contracts to use renewable energy rather than conventional fuels like gas in power plants.

For example, utility Austin Energy recently signed a contract to buy solar energy-produced electricity from SunEdison at a rock bottom price of 5 cents per kilowatt hour of energy. SunEdison will generate the power at two solar energy plants in West Texas.

"SunEdison beat out the natural gas prices by 2 cents per kilowatt," Honeyman said. "That's a prime example of what we're seeing in terms of [solar plant] projects bid by developers at really competitive prices."

Power costs from plants fueled by renewable energy and conventional fuels fluctuate state-by-state in the U.S. due to subsidies and other factors.

According to a July 2013 report from Lawrence Berkeley National Laboratories in Berkeley, Calif., the price of PV solar power plant installation has seen a "precipitous decline" year over since 2008. On average, the plant installation price has declined by 9 cents per watt (or 14%) for solar installations.

Among projects installed in 2012, the median plant cost $5.30 per watt for systems under 10kW in size, $4.9 per watt for systems ranging from 10-100 kW, and $4.6 per watt for systems greater than 100 kW in size.

A separate study by Stanford University revealed that it's possible to fulfill all of America's energy needs through renewable energy sources such as wind, solar and hydroelectric, while creating jobs in the process.

The Stanford team of researchers created 50 individual plans for how each U.S. state could transition to 100% renewable energy.

The cost of energy in the U.S. (Source: Lazard Freres & Co.)

Each of the 50 plans identifies a custom mix of wind, water and solar to power energy for all purposes (electricity, transportation, heating/cooling and industry).