In the not-too-distant past, just a few decades ago, renewable energy was on the fringes, and those who talked about the mass adoption of alternative energy technologies were seen as outliers. Their approach to the future of energy was considered unorthodox, especially when compared with that of the traditional oil, gas and coal sectors.

Instead of looking to get marginally more efficient in extracting, refining and burning conventional fuels or working to increase efficiencies in power generation, as the energy companies were doing, the pioneers of renewable energy sought something completely different - to bring clean and affordable energy to the mainstream. That goal is being accomplished, and renewable energy has moved far away from being a radical and untested concept. It is now a viable and diverse option for affordable energy.

A near-perfect storm of factors made this possible - including advances in technology and manufacturing, a serious drop in costs, several supportive policies and regulations, and an increased public demand for clean energy. Renewable energy continues to make some major progress across a number of fronts in both utility-scale and residential energy markets. A recent report from the National Renewable Energy Laboratory found that by the end of 2014, renewable electricity grew to 15.5% of total installed capacity and 13.5% of total electricity generation in the U.S. This is no small feat, considering how relatively recently clean energy has come to the grid.

Although a number of other alternative energy solutions are in the works, including hydrogen and fuel cell systems, the main types of renewable energy that are mature enough to compete with traditional sources - although at different levels - are solar, hydropower, wind energy and biomass. And though these renewable energy sources are proving to be a boon to the environment by providing a cleaner and more sustainable option for the future of energy, they’re also rapidly becoming great investments and can provide significant returns to their backers.

In particular, the adoption rate of solar energy technology - mostly in the realm of using solar photovoltaic panels to produce electricity - has jumped in the last few years. This is partially due to advancements in solar cell efficiencies, but it’s also due to a huge drop in raw materials prices over the last couple of decades, rising electricity prices, innovative financing methods, and compelling federal and state incentives for deploying solar at home or for a business.

The costs for solar cells dropped from $76.67/W in 1977 to $0.74/W in 2013, according to Bloomberg New Energy Finance. The International Renewable Energy Agency reports that solar module costs have fallen about 75% since the end of 2009. The current costs of solar come in well under the price point needed to achieve grid parity in many cities across the U.S., and those costs are expected to continue to drop by as much as 40% over the next few years, according to Renew Economy.

This means that those looking to cover their energy consumption with clean solar electricity could also be putting money back in their pockets with an investment in solar while helping to boost the renewable energy output of the U.S., which currently has about 22,700 MW of solar electric capacity online, according to the Solar Energy Industries Association.

For those who can’t install solar on their own homes or businesses for whatever reason, the growth of the solar industry has spurred the creation of an alternative known as community solar. This initiative enables individuals and businesses to join with others in ownership of an off-site solar installation - cutting energy costs and shrinking the carbon footprint for all participants.

Some renewable energy sources are already soundly beating out conventional generation modalities - in terms of both cost and cleanliness. The road to a lower-carbon future will ultimately require a great mix of renewable energy technologies, all of which can add up to a more sustainable future for all of us.

Derek Markham is based in New Mexico and writes about a variety of cleantech and green-living topics.