A Comprehensive Guide to Solar Batteries 

Solar panels can only produce solar panel electricity when the sun is shining. Which is why the ability to be able to store solar power for later use is important. Did you know that the same battery that provides power for your phone can also store solar power? Lithium-ion batteries are one way to store solar power from the solar panels. Lithium-ion batteries are the real all-stars, they make it possible for you to power your house when the sun isn’t shining and update your Instagram feed.  

Why Lithium?

There are many ways that you can store solar energy: pumped hydroelectric storage, which stores water and later uses to generate solar power: There are also batteries that contain zinc or nickel: and molten-salt thermal storage, which generates heat, to name a few. Some of the solar-powered systems are able to store large amounts of solar energy.

Lithium is a lightweight metal that an electric current can pass through with ease. Lithium-ions make a battery rechargeable because their chemical reactions are reversible, allowing them to absorb power and then discharge it later. Lithium-ion batteries can store loads of solar energy, and they hold a charge for longer than other kinds of batteries. The cost of lithium-ion batteries is dropping because more people are buying electric vehicles that depend on them.

Lithium-ion battery systems may have smaller storage capacity in comparison to other systems that store solar power, they are growing in popularity because they can be installed nearly anywhere, and when pairing these with solar-powered systems they have a small carbon footprint, they are also inexpensive as well as readily available and increasing their application by utilities. This battery system has been vital when it comes to storing solar energy coming from solar-powered systems. Growth in the electric vehicle market has also contributed to further price decreases given that the batteries are an essential component. There are more than 10,000 if these solar-powered systems that store solar energy, have been part of solar installation throughout the country, according to “U.S. Energy Storage Monitor: Q3 2018” from GTM Research and they accounted for 89% of all new energy storage capacity installed in 2015.

What is the Solar-Plus-Storage System?

Many solar-powered systems owners are looking at ways to connect their solar-powered systems to a battery so that they can use solar power at night or perhaps in the event of a power outage. To put it simply, a solar-plus-storage system is a battery system that is charged by connecting solar powered systems, such as a photovoltaic (PV) one.

In an effort to track this trend, researchers at the National Renewable Energy Laboratory (NREL) created the first-of-its-kind benchmark of U.S. utility-scale solar-plus-storage systems. When you add any sort of solar energy storage system to a solar installation there’s going to be an increase in the cost of solar panels. To determine the cost of a solar-plus-storage system, the researchers used a 100 megawatt (MW) photovoltaic solar-powered system combined with a 60 MW lithium-ion battery that had 4 hours of storage (240 megawatt-hours). A 100 MW photovoltaic solar-powered system is a rather large solar-powered system, otherwise known as a utility-scale solar-powered system, and would be ground-mount solar panels instead of rooftop-mounted solar panels.

What’s a Megawatt-Hour? 

A megawatt-hour (MWh) is a unit that used to describe the amount of solar energy a battery can store. For example, a 240 MWh lithium-ion battery with a maximum capacity of 60 MW. You can run the battery at maximum solar power for 4 hours or half solar power for 8 hours. Either way, it’s producing 240 megawatt-hours of electricity.

You are able to get a lot of solar power in a short time or less solar power in a long time. A 240 MWh PV battery software could power 30 MW for over 8 hours, but it all really depends on its MW capacity, it may not be able to get 60 MW of solar power instantly. This is why a solar energy storage system is referred to by both the capacity and the storage time or less ideal by the MWh size.

How Much Utility-Scale Lithium-Ion Energy Storage is Installed In The U.S.

From the years 2008 to 2017, the United States was the global leader in lithium-ion solar power storage use, with about 1,000 MWh of solar energy storage, and 92% of it, or about 844 MWh, is deployed by utilities, according to the benchmark report. The average duration of utility-scale lithium-ion battery storage for solar-powered systems is 1.7 hours, but it can reach 4 hours. Batteries for solar power account for the biggest share of a storage solar-powered system’s cost as of now - solar-powered systems that store solar energy, contain an inverter and wiring in addition to the solar power battery - and utilities will need big battery packs if they’re going to provide backup solar power for all of their solar energy customers.

How Much Will a Solar Power Battery Cost For a Solar-Plus-Storage Plant?

This all depends on how long you want the battery you have for your solar panels to last, as well as how much solar power you want to use.

A 60 MW storage solar-powered system will decrease in cost per megawatt-hour (MWh) as duration increases. Which means that the longer your storage lasts, the lower the cost per MWh. This is because the cost of solar power inverters and other hardware accounts for more of the cost of the solar-powered system per MWh. That’s because the cost of solar power inverters and other hardware account for more of the solar-powered systems cost over a shorter period.

The cost of solar power system will range from $380 per kWh that can provide solar electricity for 4 hours to $895 per kWh for 30-minute solar-powered systems.  ​