Solar panels do not store energy, but they generate electricity from solar radiation, storing that electrical potential elsewhere. In this article, we’ll look at how solar energy storage works.
Solar Panels and How They Work
According to Wikipedia, “A solar cell panel, solar electric panel, photo-voltaic (PV) module or solar panel is an assembly of photo-voltaic cells mounted in a framework for installation.” A single photo-voltaic or solar cell, as they are more commonly known, is illustrated below in Fig 1.
Single Solar Cells
Single solar cells are often used to power small devices like garden lights, camping accessories, and toys (Fig.3). They are more commonly grouped together to form higher output solar panels.
In other words, a solar panel is little more than a collection of separate solar cells mounted and connected together in a group. Single cells in relation to solar panels are illustrated in Fig.2.
The solar cells that make up a solar panel system are actually fascinating devices. They allow a very interesting and useful reaction to take place when exposed to solar radiation (sunlight). And that reaction happens at an atomic level. And no, not atomic as in weapons of mass destruction! In essence, they are harvesters of the power of solar plus storage system components such as lithium-ion batteries.
An overview of the structure of a solar panel is illustrated below. Illustration courtesy of ResearchGate.
When sunlight strikes a solar panel, the panel allows electrons to be “knocked” free of their bonds to their atoms. And that electron release is where the magic of solar power originates from.
When the electrons flow in the panel structure, it causes what is known as a potential difference between the surfaces. This is what causes an electrical current to flow from one surface of the panel to the other, allowing the system to solar energy storage or return it to an electric grid.
The flow of electrons is channeled through metal strips that join all the individual cells and cell groups together. At the end of the circuit, the flow of solar energy exits the panel. It can then be used directly or coupled with the output of one or more other panels. That flow of electricity can then be used directly or in solar energy storage, such as lithium-ion batteries for later use.
Placing the last words of that sentence in bold italics is important, as it essentially answers the question at hand. This is because storing harvested solar energy is one of the essential foundations of any solar system. The basics of the solar power generation and solar battery storage concept are illustrated in Fig. 4 below.
As you can see, the solar panel generates electrical energy for solar radiation. That energy passes through a charge controller, which, in turn, charges the lithium-ion battery correctly. In systems where small, low-voltage devices are powered, the stored energy can be drawn directly from the solar energy storage battery.
In larger, home or industrial supply systems where high voltages are required, the picture is a little different. Here, an inverter is included at the end of the supply chain, as illustrated in Fig. 5. The inverter steps the low voltage DC power from the battery up to high voltage AC consumer power.
Storing Solar Energy
In the simplest applications, solar-generated electricity is used immediately and not stored in batteries at all. This is typically the case with simple solar-powered toys, as illustrated below.
These items will only work while exposed to sunlight and cannot be used during hours of darkness. They need some other way to keep the solar energy stored.
As solar-powered devices become increasingly sophisticated and power-hungry, batteries become a necessity. This is particularly true of devices designed to use solar potential to charge during the day while working at night. Solar lighting is perhaps the best example of these types of devices.
To achieve this, the devices will use energy from solar panels to charge a set of lithium-ion batteries during the day. The energy stored in the batteries is then used to power the device during the night.
In the case of toys or small stand-alone devices, the recharging function is handled by the device’s internal circuitry. As mentioned previously, in larger systems, inverters and sophisticated charge controllers deal with charging functions.
Storing Solar Energy in Solar Batteries
Solar batteries can range in size from large deep cycle examples to small nickel-cadmium (NiCd) batteries similar to AA types. Although they differ enormously in size and functionality, they all share two basic characteristics.
- They’re typically purpose designed to be used in solar-powered devices.
- They’re charged by solar-powered circuitry.
Often, the lead-acid batteries used in solar devices are presented in packs with a dedicated output/input lead. They can also include their own charge control circuitry.
Can I use any rechargeable battery for solar recharging?
Essentially, yes, you can, but it is not a sound practice. The recharge station on your particular system or device will use specific lead-acid batteries, as illustrated below in Fig. 6.
These are, more often than not, designed specifically for this purpose. Substituting them for conventional rechargeable batteries may lead to the risk of equipment damage, fire, or injuries.
A Quick Tip: Optional Ways to Use Excess Solar Energy
One thing that is abundantly clear is that solar panels generate electricity, saving you money on your power bill. And that would make installing solar panels in your home a sound investment, right? Well, it could be a lot more attractive and lucrative than you think.
Net metering is a great way of using excess solar system power to either increase savings or even earn money. Although net metering is not available everywhere, at least 38 states, four territories, and Washington D.C. offer this attractive option.
So, do solar panels store energy? It should be obvious now that, contrary to some popular misconceptions, they don’t. They absorb solar radiation and turn that latent energy into a usable electric current. However, if storing solar energy is the question here, it will certainly not be the panels doing it but rather a solar battery.
And one should not think that this is any different for devices like portable solar power stations. They also use internal batteries to store solar energy produced by the solar panels. This is true of all portable solar-powered or charged devices. In short, they all generate power from a source of energy, such as solar radiation. Batteries are then used to store energy.
If you want to capture the lightning in a bottle, you’ll have a battery or a series of batteries installed. This is seldom an issue because almost all solar panels or systems include them. If not, there are many aftermarket solar-compatible batteries that can be added to your system to facilitate storage.
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