Based on current evidence, the state of California is well on its way to achieving its goal of becoming the United State’s leader in renewable energy. The most obvious proof comes in the number of gigantic solar farms that have sprung up all over the southern part of the state and the huge rows of wind turbines that can be seen just outside most major and many minor cities.

However, there is another much less visible investment going on that has the potential to revolutionize renewable energy in California and should go a long way towards helping the state meet its target of producing at least 50 percent of its electricity with renewables by 2050. Hidden away from view in various industrial parks and warehouses are huge banks of lithium-ion batteries, which are set to play a key role in improving the efficiency and potential of California’s solar and wind farms.

Batteries have long been a part of many smaller-scale commercial and residential solar systems. They are an essential part of any off-grid system, as the battery stores any excess energy to ensure the building still has access to electricity even when the sun isn’t shining. More and more businesses are also turning towards solar power as an emergency backup in case of power outages.

Nonetheless, batteries have typically never been a part of any large-scale renewable energy installation. The problem with this is that leads to wasted energy. Under ideal sunny or windy conditions, California’s major solar and wind farms can essentially produce much more electricity than is actually needed at that time, and unfortunately, all of this excess typically goes to waste.

By connecting these installations to batteries, utility companies are now starting to be able to collect and store all of that excess energy. The company can then utilize this energy anytime the sun isn’t shining or wind isn’t blowing instead of having to rely solely on non-renewable sources.

The state’s effort to increase its energy-storage capabilities began in 2013 when California announced a goal of having 1,325 MW worth of storage before 2020. Although this goal hasn’t quite been met yet, it looks likely that the total amount of storage will far exceed this amount before 2020 due to the fact that so many utility companies have thrown their weight behind the initiative. In fact, over 36 percent of the country’s total storage capacity is in California, and additional storage projects continue to pop up on an almost weekly basis.

Already other state’s like Massachusetts and Oregon are following suit. Still, many policymakers around the country are watching California as something of a litmus test. By paying close attention to the renewable industry in California, other states are able to learn what works and what doesn’t.

One of the main reasons that batteries are suddenly starting to play a much bigger role in renewable energy is that, like the cost of solar panels and other renewable generators, the price of lithium-ion batteries has dropped dramatically in recent years. At the same time, technology continues to find new ways to make them even more effective. For this reason, batteries are also set to play an increasingly large role in residential and commercial solar installations and also in the electric car industry.

Already many homes and businesses are having batteries installed, which allow them to store their renewable energy and use it during times of peak electricity prices. Even electric cars feature hugely improved batteries compared to just a few years ago. For instance, Tesla offers a battery that can store enough electricity to power a home for over three days.

Still, lithium ion batteries may eventually begin to face challenges from other battery sources, including hydrogen and molten salt. These and other battery technologies have also seen a major increase in investment. Of course, the type of battery doesn’t really matter so much. What is really important is the potential that these batteries have to completely revolutionize the energy industry and hopefully help finally put an end to our overreliance on fossil fuels.