What is solar energy storage?
Solar energy storage is devices that can gather the electricity generated by the 550W solar panels, store it inside the device and then release it when the energy is needed – for example, after sundown or during power outages.
How much energy you can store depends on the type of storage system and its energy capacity, meaning how much energy it can hold at a given time. An average solar battery has a total of about 10 kWh, though there are also batteries that can store up to 13.5 kWh.
Thermal or hybrid storage systems can store far more energy inside themselves (Pumped Hydro Storage capacity is, on average, 100 times higher than any available battery solution), but they are also far more complicated and costly to build.
Why is having an energy storage system so important for solar panel owners?
The interest in solar panel systems is booming as homeowners and businesses are looking for ways to lower their energy costs and become more environmentally friendly.
As they are, solar panels also have some limitations though.
The main disadvantage is that the panels can only generate energy when the sun shines on them. So during cloudy weather or winter when it’s getting dark quickly, the solar panels’ efficiency naturally drops. On the other hand, during sunny days the solar panels often generate far more energy than needed – but the power might be wasted since panels can’t store it themselves.
Solar energy storage systems can solve both of those problems though, as they can gather the excess electricity, store it and then let companies use it whenever they need it. With the capacity of some of the storage systems, businesses can even gather energy in summer (when renewable energy sources are producing more electricity than needed) and then use it to power their company in winter, when there is a high demand for electricity but a low supply of solar energy.
What are the main types of solar energy storage?
Choosing the best method of storing the energy coming from the panels might be slightly tricky because of the variety of different types of storing energy available now. On one side, that allows companies to choose the best storage method for their needs – the downside is that it can be quite confusing to understand how each storage method works and their requirements.
Let’s have a quick look at the available solar energy storage types and their main features.
1. Solar batteries
Solar batteries are now one of the most commonly used devices for storing solar energy, mainly thanks to how much cheaper they have gotten in recent years.
The price of Lithium-ion batteries has fallen 89% from more than $1,200/kWh in 2010 to $132/kWh in 2021, making them much more affordable for households or smaller businesses. They are now also one of the easiest ways to have a backup power source when the panels don’t generate enough energy or the grid electricity supply has been cut.
There are four types of solar batteries available on the market now:
Lead-acid batteries: Lead batteries have been on the market for decades, and they are still pretty popular. They are known for being reliable, plus they are one of the cheapest battery types available. Unfortunately, they are also quite bulky and heavy and should be placed in a well-ventilated area, which might limit your options for where to place them. Lead batteries also have a lower-than-average lifespan (from 5 to 10 years) and require regular maintenance to keep them in the best condition possible.
Lithium-Ion batteries: They are one of the newer battery types but they quickly gained popularity as they are much smaller and lighter than lead batteries and can store more energy inside them. Their lifespan is also much better than the lead batteries (they can keep working for 10-15 years) and require little to no maintenance. However, even though the price of lithium battery is quickly dropping, they are still one of the more expensive types.
Nickel-cadmium batteries: Ni-Cd batteries are very durable and can function even in extreme temperatures, so they are often used for solar energy storage. Their main disadvantage is that cadmium is a highly toxic element that can have a significant negative impact on our environment, so disposing of them is, unfortunately, quite problematic.
Flow batteries: Flow batteries are a new type of battery where a water-based electrolyte flows between battery chambers or tanks. As they can be extended to virtually any desired capacity just by adding extra tanks and have far longer longevity than any other battery type (even up to 30 days), they are gaining popularity. The main problem, for now, is that the tanks must be pretty large, making them very expensive and difficult to set up.
The main problem with all available battery technology types is that their lifespan is the shortest of all available storage systems – on average from 5 to 10 years. Their capacity is also limited, so depending on whether they want to use the solar storage only as a backup or they want to go off-grid, businesses will often need more than one battery to cover their needs – and that might significantly up the installation cost.
2. Thermal storage system
The second option is to use a thermal storage system. Thermal energy storage uses a fluid (such as molten salt) or a solid material to gather the heat and then store it in an insulated tank until the energy is needed. The heat can later be converted into superheated steam to power turbines and generate electricity.
As thermal storage systems can store large amounts of energy for months, that makes them a good option for companies that want to ensure they have enough energy for daily use during times when solar production drops. What’s more, molten salt thermal energy storage can be heated and cooled daily for at least 30 years. The downside is that thermal storage systems require plenty of space as the tanks have to be pretty large – which also means that the upfront costs might be quite high.
3. Pumped-Storage Hydropower
According to the 2021 edition of the Hydropower Market Report, Pumped-storage hydropower systems currently account for 93% of all utility-scale energy storage in the United States. Here, electrical energy is used to pump water uphill into a reservoir when energy demand is low and then the water is allowed to flow back downhill and turn a turbine to generate electricity when demand is high. The water can then cycle between upper and lower reservoirs for decades.
Setting up a pumped hydro storage system is a pretty complicated process though, as it requires plenty of space, a suitable landscape (the reservoirs must be at different elevations), and also natural or man-made places that will act as water reservoirs. That means that building such a storage system might take years, as companies will need to find a suitable location, get all required regulatory permits, plan the installation, and then start the system construction. Obviously, it also means that this method of storing energy will require a large upfront capital investment as well.
How to pick the suitable solar energy storage method?
So what is the best energy storage option? Sadly, we can only answer this question with “it depends on what you need.” To pick the right technology, you should first research your main goals for energy storage systems, how much storage capacity you will need the systems to have, and if there are any additional requirements the storage systems should meet.
Adding a solar battery (or batteries) is usually the fastest way to add a storage system to the solar panels. As their capacity and lifespan are limited though, they might not be a good solution if your business has large energy needs. In this case, you might need several batteries to cover your needs and the installation costs might become staggering.
