Storing the Sun

In the US and globally, it’s clear that the solar industry has been growing remarkably. Solar panel installations have skyrocketed, solar jobs have outpaced the economy, and renewable energy has recently gained a notable share of US electricity generation.

Yet, every industry that undergoes a growth spurt is also vulnerable to growing pains.

In the thriving solar industry, one concept deemed the future of solar is now in the center of a current crisis. Solar plus storage, or storing electricity from solar panels, is not only the forefront of the industry, but also a significant challenge in the present. While installations have skyrocketed, storage usage and technology has yet to keep up.

Power curtailments

California power curtailments (in MW-hours). Source: LA Times/P. Krishnakumar.

Last year, there was such an extreme surplus of electricity on California’s grid that solar plants were ordered to halt production. According to the California Independent System Operator, in 2016, “305,241 megawatt hours of solar and wind electricity were curtailed — a loss of enough carbon-free electricity that could have powered about 45,000 California homes for a year.”

Most utilities have blamed local power officials, who have been pushing compliance with the new California state law that mandates 50% of power be renewable by 2030, while utility companies are left to handle the surplus. Utilities are continuously worried about a grid overload, especially since many residential homes and businesses install solar panels with little regard to the idea of storage. The utility companies have even resorted to paying Arizona, a neighboring state, to take some of its surplus electricity. This temporary measure has taken some pressure off of utility companies, but the surplus of solar energy is only expected to grow.

Part of the problem is electricity generation from solar is uneven, spiking at a time when demand might not necessarily be high. And when usage is high, i.e. air conditioner running through the night, generation is zero. Without storage, there’s not only a hazardous surplus during the day, but no way to redirect that electricity for later use. However, when an issue of this magnitude arises, companies are quick to try and be the first to market with a solution.

Inventive solutions

In Nevada, SolarReserve built a large solar plant with thousands of sun-tracking mirrors facing a 640-foot-tall tower in response to the solar efficiency problem. The project, which is deemed to be the first of its kind in the world, leverages heated molten salt inside of the tower to generate electricity for up to ten hours after sundown. It achieves this by circulating molten salt through a specialized piping system during the day, and holding it in storage tanks at night. When electricity is needed, molten salt is sent from the hot tank (stored at 1050⁰F/566⁰C) through a heat exchanger to create super-heated steam that powers a conventional steam turbine.

Ice Energy’s Ice Bear technology. Source: Ice Energy.

Similarly, a California company named Ice Energy looks to solve California’s crisis with the concept of a thermal energy storage unit, nicknamed the “Ice Bear”. The company, which had its first completed order in 2014, hopes to become standard technology in the future. The Ice Bear uses a system of copper coils to pump cold refrigerant through hundreds of gallons of water to make ice; typically during off-peak hours. It monitors and controls its own cooling process, shifting the majority of the electricity used for cooling from peak to off-peak hours. When set to provide cooling, the Ice Bear turns off the air conditioner compressor and uses its stored ice to cool the building for up to 6 hours, consuming only 5% of the electricity usually required.

Choosing the Right Chemical Composition for Your Battery

Source: Energy Sage.

This recent rise of start-ups and innovative technology is great news for the solar industry, but what about present-day consumers? Residential consumers, or most businesses, can’t afford to wait until innovative technology becomes available to the masses. One solution, especially ideal for those without net metering options, is to purchase a solar battery for a solar-powered home or business.

Tesla’s new solar battery has generated excitement among consumers, and may be the perfect solution for residential homes looking to stop wasting their surplus solar. The new lithium ion battery, manufactured partially by Panasonic, promises high efficiency storage of electricity from solar panels and even the ability to draw electricity from the grid for later use when rates are low.

Outside of Tesla’s new Powerwall battery, there are still plenty of options available for consumers with a range of prices and efficiency. Navigating across the solar battery landscape may also seem difficult, but there are plenty of resources to help consumers find the right price and technology for their consumer needs. There are a number of great guides online, as offered here or here, with thorough explanations on how to assess different types of batteries.

Evidently, solar plus storage is the forefront of solar energy. It’s a great challenge, but utilities and startups are rapidly working towards solving it. Soon, we’ll be storing the sun for later and reaping its benefits at our demand.

If you need solar design and engineering services, contact us here or email us at