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When Hurricane Maria hit Puerto Rico in 2017, many residents lost power for months – and some neighborhoods are still struggling to get electricity back up and running.

Puerto Rico had solar panel fields generating power before the hurricane, but much of it was inaccessible when the grid (or the network that delivers electricity to people) went down.

That’s one of the biggest challenges with solar energy, which provides an alternative way to power homes and businesses. The technology is still limited, not only because sunlight collection can be inconsistent on cloudy days and unavailable at night, but also because rural or remote areas often lack proper infrastructure.

Some companies are working on solutions to make solar energy technology more resilient and efficient.

Solar panel debris is seen scattered in a solar panel field in the aftermath of Hurricane Maria in Humacao, Puerto Rico on October 2, 2017.

“Solar, in the old sense, is where the system shuts off with the grid,” Yotta Solar co-founder Omeed Badkoobeh told CNN Business. “The future of solar is where systems are independent of the grid.”

After 10 years in the solar industry, Badkoobeh teamed up with researcher and co-founder Vikram Iyengar in 2016 to build a device that stores energy more effectively. The device, which holds batteries, can be placed under photovoltaic solar panels and is able to self-regulate the battery’s temperature.

The device, SolarLEAF, can be kept outside on its own, which is typically difficult to do to batteries without shortening their lifespan, especially in regions with extreme temperature fluctuations. The storing method can help cut down on costs by 40%, according to the company, because placing the device under solar panels means it’s not taking up additional space. The ability to self-regulate temperature means it doesn’t need expensive extras like an HVAC system to stay cool.

It regulates the temperature of the battery case by working like a well-insulated ice chest. It has an inner layer that uses very little energy to protect the battery, which can last over 20 years in the device, the company said.

The SolarLEAF also helps to create a microgrid system that works with or without the electrical grid.

In the wake of Hurricane Maria, Puerto Rico is installing microgrids to minimize the effect of future storms. Yotta Solar is in early talks with a Puerto Rican company to pilot its technology there. The company is also working with Translight Solar, which provides affordable solar power in Ghana, and 10Power, a company that’s investing in renewable energy projects in Haiti that can be paid back over time.

“We’re trying to create a durable infrastructure unit and work with markets where there are huge pain points,” Badkoobeh said.

Yotta Solar's energy-storing devices can be kept under photovoltaic solar panels and self-regulate the temperature of the batteries inside.

Renewable energy, like solar, is expected to be the fastest-growing source of electricity generation in the next couple of years, according to the US Energy Information Administration. Solar energy also doesn’t produce air pollutants or carbon dioxide – and systems placed on buildings have few negative effects on the environment – and it’s expected to be cheaper than fossil fuels by 2020, according to the International Renewable Energy Agency.

Companies such as Tesla and the German tech company Sonnen, owned by Royal Dutch Shell, are also creating batteries that store energy and can be paired with solar panels.

Dan Whitten, vice president of public affairs for the Solar Energy Industries Association, said energy storage is key to transitioning toward a clean energy economy.

“Storage demand is booming for both distributed and large-scale solar projects, and costs for solar and storage applications continue to fall,” Whitten told CNN Business. “The price of solar has dropped by 70% over the last decade, making it the most affordable option now in many parts of the country.”

Storage innovations are a growing area within the solar energy industry, according to Brett Simon, senior energy storage analyst with Wood Mackenzie Power & Renewables. He said state programs, such as NY-SUN in New York, offer incentives for developing solar energy systems that include storage but there’s still room for improvement.

“Cost continues to be a barrier for energy storage,” Simon said. “Any innovation that can lower balance of system costs is a boon to the market.”