How Do Solar Batteries Work?

Battery Storage Technologies

Residential solar systems typically use one of two types of solar batteries: lithium-ion or lead-acid batteries. Lead-acid batteries used to be standard in the industry, but more and more often, solar panel companies are using lithium-ion batteries because they can store more energy for extended periods of time. At Axia Solar, we offer lithium iron phosphate batteries, a type of lithium-ion battery produced by Qcells.

How Batteries Store Energy and its Uses

Like any energy source, batteries use chemistry to store energy in the form of chemical potential. The energy from the sun holds the chemical potential to be energy, and the battery takes it through the process to become energy that becomes electricity. Since solar panels can create energy but not store it, you need a solar battery to store the extra energy that is not being used immediately.

Homeowners that attach battery storage to their solar system can consider a few different variables when choosing how much battery capacity their home needs. When evaluating battery storage, the key factors are how large your system is (i.e. how much electricity it can produce) and how you plan to use your stored power. Battery power is most effectively used for backup power in an outage, when grid electricity prices are at their highest, or some combination of the two.

How Lithium-Ion Batteries Work

Lithium-ion batteries are used in many common technologies and are generally considered safe. These batteries move lithium ions through an electrolyte inside the battery. Ions are particles that have gained or lost electrons, so moving lithium ions means free electrons are moving around. The buildup of these free electrons is how the batteries build up and store electricity. You can charge and discharge lithium-ion batteries hundreds of times which in the case of solar battery storage means batteries tend to last between 5 and 15 years.

How Solar Batteries Work With a Hybrid Inverter

How does a solar battery work with a hybrid inverter? A hybrid inverter can convert AC electricity into DC electricity and vice versa. With a hybrid inverter, you don’t need one inverter to convert electricity from your solar panels and one to convert electricity from your solar battery — a hybrid inverter does both jobs. They can work with or without battery storage, and if you install one without it, you can easily add battery storage down the line. This flexibility is making hybrid inverters a popular choice as time goes on.

AC-Coupled Storage vs. DC-Coupled Storage

Your solar panels must be wired to your battery storage system, which is called coupling. This will either be achieved through direct current (DC) coupling or alternating current (AC) coupling. The difference is that solar panels make different paths for electricity depending on the type of coupling used. The solar cells on your solar panels produce DC electricity, and solar batteries can only store DC electricity, but DC electricity has to be converted into AC electricity to be used in your home. There are various ways to connect a solar battery to your solar power system to make that happen.

Which is better?

Solar panels create DC electricity that flows directly through a charge controller and into a solar battery. The current doesn’t need to change before storage, and it doesn’t need to be converted to AC electricity until the electricity gets sent to your home or out to the grid. Because of this, a DC-coupled storage battery is typically more efficient, but it needs a more complex installation, making it more expensive and difficult to install.

How Do Solar Batteries Work with a Solar Power System?

Solar batteries work with solar power systems to generate and store electricity for your use. In a DC-coupled system, sunlight hits the solar panels, and the solar panels convert the energy from the sunlight into DC electricity, which is stored in the battery. When the DC electricity leaves the battery, it goes into an inverter that converts it into AC electricity for use in your home.

In an AC-coupled system, the process is similar at the beginning. But after the AC electricity is used in your home, the excess energy goes through another inverter to be converted back into DC electricity so it can be stored for later use. When used later, it has to go back through the inverter to be again converted into AC electricity for your house.