Just a few years ago, critics said a lack of viable storage options hindered the expansion of solar. But a number of clever startups, innovative storage companies and battery manufacturers have offered new storage options, with impressive products hitting the market almost every week. Solar storage is plugging PV into the future.

In fact, GTM Research and the Energy Storage Association’s (ESA) U.S. Energy Storage Monitor confirms that storage technology vendors are growing their businesses and, furthermore, the downstream value chain (such as inverter manufacturers and storage system developers) is growing faster than ever. The energy storage market was worth $128 million in 2014.

In all, 61.9 MW of storage was installed in the U.S. last year, 40% more than 2013, according to the Monitor. The vast majority of these projects (90%) were in front of the meter (utility installations). The remainder were mainly on “non-residential” commercial, education, military or non-profit projects, while only 1% were on residential installations. However, storage use in all projects dramatically increased at the end of last year, which makes the Monitor’s experts note the market’s maturity and they expect it to break out in 2015.

IHS also released data in its Energy Storage in PV Report – 2014. Sam Wilkinson, research manager for solar and energy storage for IHS Technology, noted the commercial PV energy storage market in the United States has gained huge momentum in recent months. “Commercial buildings are subject to peak demand charges, which are based on the maximum power drawn from the grid during the billing period,” he said in the report’s press release. “These charges can make up a significant portion of a business’s electricity bill. However, using a battery and PV to reduce peaks in grid power consumption can reduce these costs significantly.”

It takes the right policy, regulations and whole markets to make storage viable, so the U.S. storage market is highly geographically concentrated. Residential storage has worked best in California, while utility storage has been successful in the PJM interconnection territory (which encompasses Ohio, Pennsylvania, Tennessee, Virginia and parts of surrounding states). After Superstorm Sandy, the PJM region heightened its focus on energy response storage to make systems more resilient.

“I think there is just a general sense of concern when it comes to the grid, especially after Sandy,” said Josh Ross of Ross Solar Group in Connecticut. “But storage systems can be expensive. It requires a very customized approach and good talent to assess needs versus costs for each project. If costs were to decrease and technology advances, I believe more folks would opt to have a battery back-up installed.”

However, Wilkinson said incentives like the Self Generation Incentive Program (SGIP) offered in California are making the economics of storage systems extremely attractive. The SGIP provides rebates for qualifying distributed energy systems installed on the customer’s side of the utility meter. “But there is no guarantee that electricity tariff structures won’t be adjusted, which could affect the economics of existing systems,” he added.

The Monitor also reports new opportunities are coming to light for both residential and utility storage in other states such as Oregon, Texas and New Jersey.

GTM and ESA predict that 2015 is expected to be the biggest year for storage yet, as experts anticipate 220 MW of storage deployment, more than the previous two years combined.