What Is Solar Energy Storage, and How Does It Work?

Solar panels are one of the most revolutionary advances in modern electricity generation. However, even the most die-hard solar advocates can admit that panel systems alone have one key weakness: they can only produce power when the sun shines. Storage changes everything. It’s the key to maximising solar power and ensuring it’s available even when a cloud passes by, it rains for an entire day, or the sun goes down. It also provides peace of mind and enhanced energy independence.

So, what is solar energy storage, and how exactly does it work? Below, we explore all this, plus a storage system's advantages and key components.

Solar battery storage is a technology that captures and holds onto electricity, then releases it as needed. It’s the intermediary between panels and your home’s appliances and devices. This means you can store excess energy that would otherwise get lost, thus leveraging solar power even when the sun’s not out.

Most energy storage is in the form of rechargeable batteries. Some electricity will always be lost when converting and retrieving it. However, storage is still worth it because it provides flexibility in your energy use timing beyond solar’s strict parameters of performing only when the sun is shining.

Solar energy storage capacity varies, depending on how much energy it can store at one time. It also differs in its output, which is how much energy it can release at once. The greater the capacity, the more energy it can store, and the greater the output, the more high-wattage appliances and devices it can power.

Are you wondering how batteries store solar energy? Solar batteries receive excess power that isn’t being immediately used. The panels create DC power, which gets converted into AC in the inverter for household appliances and devices. Any additional power beyond your home’s current demand is sent to the storage unit in DC form.

From there, the DC power is used to charge the battery, which stores this energy until you have the demand for it. When this power is needed, it discharges to your appliances and devices, whether the sun is out or not. It allows you to use all of the solar power your system generates without any of it going to waste.

To determine the size of your solar battery, the number of panels you need, and their expected cost, you should start by calculating your electricity use from your bills. From there, you should design an array that can at least satisfy that demand. However, we recommend a system that goes beyond that demand to allow for some power loss through conversion and discharge. 

Solar power storage requires more than just a rechargeable battery. You need all the elements of a complete system, from the panels and the battery to the inverter and other accessories.

Your panels are the workhorses of your system. They capture sunlight and produce clean, renewable electricity. You can have an energy storage system without panels, but it won’t be solar battery storage. Pairing with solar is preferred, as it doesn’t require energy from the grid and is free to generate after purchasing the panels.

The inverter ensures that the energy your panels generate is usable. It receives DC power and turns it into AC power, which is required by most household devices and appliances. Some batteries and panels may have a built-in inverter, so check the product specifications to see if it’s included.

The battery is your storage unit. Most batteries are made with Lithium-Ion-Phosphate (LiFePO4) because of their long lifespan, high energy density, and enhanced safety.

In addition to the above components, you’ll also need a critical load panel, which controls what gets powered off when grid power goes out. Unless you have an extremely robust battery with capacity and output large enough to power your entire home for an extended time, your solar battery will likely need to prioritise sending power to specific devices and appliances. The critical load panel is where you determine the most critical loads, so this part must be set up correctly to ensure it doesn’t demand more than your battery’s capacity or output can provide.

Several other small components tie the system together and ensure each part works properly. These accessories include fuses, circuit breakers, cables, mounting hardware, safety equipment, and battery enclosures. 

Modular home battery systems like the EcoFlow PowerOcean (Single Phase) also have mobile apps to give you even more control and supervision over your system.

When you combine storage and solar, you reap these advantages:

Solar electricity must be immediately consumed if you don’t have storage. This means you don’t have power on cloudy days, after sunset, or if grid power fails. Storage, on the other hand, can hold onto power for later use. Consider it an insurance policy for when the sun doesn’t shine.

Solar can produce small fluctuations in generation if a cloud passes by, for example. Storage firms up your supply and ensures that any changes like this won’t significantly impact your output.

If your array is connected to the grid and you don’t have storage, you will be out of power just like everyone else when the grid fails. Storage is a workaround for outages that maximises solar power, allowing you to draw from stored power during blackouts to ensure the continuous operation of your essential appliances.

Homes with sun-powered systems without storage will still need to draw energy from the grid at night or when it’s cloudy, so you’ll still receive a monthly energy bill. You can significantly reduce these bills by adding storage and lessening your reliance on the grid.

The cost depends on several factors, including where you live, potential incentives that may be available, and the battery size you want to add. For most systems, you can expect to pay between £2,000 and £12,500.

Solar battery storage can last between 5 and 15 years, depending on the battery chemistry. Usage also comes into play, as battery performance over time can be measured by cycle efficiency. Most last 1,000 to 3,000 cycles before dropping to 80% of full capacity.

Despite the high upfront cost, solar energy storage is well worth it because of the long-term savings. It maximises your use of your panels, ensuring no power goes to waste, and you can still use solar energy even when the sun is not out.

Solar energy storage is the solution to solar power’s weakness. Instead of only using this power when the sun’s out, storage allows you to hold onto excess energy for later use at night, when it’s cloudy, or when grid power goes out. Home battery systems like EcoFlow PowerOcean (Three-Phase) take your solar panel array to the next level, giving you peace of mind and true energy independence.