Source: The U.S. Army on Flickr.

America's military is investing billions of dollars to harness the power of the sun. However, instead of harvesting that energy for next-generation weaponry, it's doing so to fuel its fighting forces. That move is evidenced by the fact that solar represents 58% of the renewable energy capacity additions the Department of Defense has planned through 2017.

Why is the military going green?
The military's moves to go green are more about saving lives and money than about saving the environment. By going green, the Department of Defense can save some of the more than $20 billion it spends each year on energy as it consumes over five billion gallons of oil. Not only that, but it can save lives on the battlefield by cutting down on refueling convoys. In some years, one out of every 24 refueling missions sadly resulted in a U.S. casualty.

That said, the environment will clearly benefit from these moves. That's one reason President Obama is pushing an ambitious plan expected to cut the military's greenhouse-gas emissions by 28% by 2020. While that plan is leaving all options on the table, the numbers show a very compelling future for solar energy within the U.S. military. Because of that, investors should take a closer look at the industry, as solar has the potential to really brighten up their portfolio.

How to invest in solar
Traditionally, defense contractors like Lockheed Martin (LMT 0.29%) were investors' only option to profit from the growth in military spending. However, when it comes to investing in the military's spending for solar power, there are a few more options these days, despite the fact that even Lockheed Martin is installing small-scale solar power systems on U.S. military bases.

Source: U.S. Army Environmental Command on Flickr.

One company that has worked with the U.S. military in the past is SunPower (SPWR -13.37%). In 2011, it completed a 6-MW project for the U.S. Air Force Academy in Colorado. The project provides 11% of the base's electricity needs, saving it a half million dollars each year, all while offsetting 9,400 tons of carbon dioxide emissions each year, which equals the removal of 40,900 cars from the road over the project's 25-year lifespan. That's in addition to the company's 14-MW project at the Naval Air Weapons Station in California. That project will save taxpayers $13 million over its 20-year lifespan as it provides the base 30% of its electricity. Because of its past successes with the military, we can expect SunPower to continue receiving military contracts in the future. 

Both of those projects are larger-scale projects that supply a portion of a base's power. However, an interesting future opportunity for the military is its investments in adding solar to military housing complexes. A compelling investment opportunity here is SolarCity (SCTY.DL), which signed a five-year contract worth more than a billion dollars. As part of the contract, it will add solar panels to as many as 120,000 military housing units as part of the Solar Strong project. It is the largest residential solar project in American history.

Meanwhile, crowdfunding start-ups like Mosaic are also providing investors with the opportunity to invest directly in solar projects on a local level. One of its opportunities is to raise money for a 12.3-MW project that will add solar panels to 547 homes at the Joint Base McGuire-Dix-Lakehurst in New Jersey. The project is expected to meet 30% of the electricity needs in the community as well as $1.3 million in annual energy costs.

Investor takeaway
The U.S. military is spending a lot of money to capture the power of the sun. As it does, it's creating opportunities for investors to profit alongside it as the military saves lives and money. Bottom line, solar's future is looking very bright as it becomes the new secret weapon to fuel America's military.