Call solar power the second best thing in clean energy. Solar power stocks have soared since concerns about a nuclear meltdown in one of Japan’s nuclear power plants have sent investors running to alternative clean energy companies.

The market move indicates that investors in clean energy prefer nuclear power as a first option over solar power. That’s because solar power, which uses flat photovoltaic panels that absorb sunlight and convert it to electricity, is still in infancy. Typical wafer-style solar panels can capture around 30 percent of the sunlight shining on them and convert it into electricity. Flexible, thin-film photovoltaic cells that can be placed on most surfaces can only capture anywhere from 15 to 20 percent of the sunlight shining on them.

Nuclear power produces energy by generating controlled nuclear reactions that produce tremendous amounts of heat. That heats up water, which produces steam that spins a turbine. The turbine produces electricity. Nuclear power is considered cleaner than fossil fuel burning power plants, which use natural gas, petroleum and coal. Burning all of those produces greenhouse gasses.

But a critical nuclear reactor nearly experienced a meltdown after an 9.0-magnitude earthquake rocked the northeastern part of Japan last week. Plant officials were able to halt the nuclear reaction by withdrawing the fuel rods that power the reactor, but residual reactions and heat were still causing problems as of Monday. Investors are basically betting that the media frenzy that has taken off as a result of the snafu will generate some additional buzz for solar power, another form of clean energy that has no negative byproducts.

The United States solar power industry seems to be doing well and is on track to have a good year. It’s attracting investment from companies that want to buy up demand. Chinese player LDK Solar, for example, picked up a $33 million majority stake in Solar Power, Inc. There are a number of solar power companies that have already gone public. The U.S. solar power industry also grew 67 percent to $6 billion in 2010, up from $3.8 billion in 2009, according to the Solar Energy Industries Association.

Shares of FirstSolar, which produces thin-film flexible photovoltaic cells, were up more than 4.5 percent in midday trading. Shares of Suntech Power, a Chinese solar panel manufacturer, were up 3.4 percent in midday trading. Other solar panel companies, like SunPower and LDK Solar, were all up more than 1 percent.