A solar battery can store energy for later use and can be a critical part of any PV system. But how does it work, and why would you need it? Also, what type of this battery would fit your solar installation? In this article, we’ve answered these questions and many others about the solar energy battery.
What is a Solar Battery?
A solar battery is defined as an electrochemical storage solution that’s specially designed for photovoltaic systems. Electrochemical means the battery can use voltage to produce a chemical reaction leading to stored energy and vice versa.
A solar storage battery can be a single device for use with a small solar system or a bank of batteries for a large array of panels; it depends on the required backup storage capacity but, more importantly, on the size of your solar installation.
How Solar Battery Works
From its definition, we can see that a solar battery relies on an electrochemical process to work. That means a chemical is involved in its charging (energy storage) and discharging (energy release) processes. Here is how a solar battery works in brief.
- The typical solar battery comprises these significant parts: anode, cathode, and electrolyte. The anode is the battery’s negative side, while the cathode is its positive side.
- The electrolyte is the chemical solution that allows the movement of electrons to either store energy or send it out through an external circuit.
- During charging, the external electrical force causes electrons to flow from the anode to the cathode. The opposite happens the battery releases the stored energy. This movement of electrons then manifests as current, which can power an electrical appliance or circuit.
A solar battery storage system is usually either AC or DC coupled. This determines how electricity flows to the storage from the panels, among other things, such as system efficiency.
DC Coupled Solar Battery
In a DC-coupled solar battery setup, the power generated by the array only passes through the charger controller on its way to the battery and no other device or system. This produces an effective and efficient solar storage system since the energy losses are minimal.
AC Coupled Solar Battery
This configuration has the path that currently takes being linked to the inverter. Here, the current is converted from DC to AC for use by loads. The amount to be stored then passes through another inverter before it can reach the storage. With these steps, the energy losses are significant in this type of setup.
Types of Solar Batteries
Solar batteries mainly vary based on the type of electrolyte used. Given these variations, one type of device will fit a particular application more than another, and users must choose what best fits them. In light of that, these different types of solar batteries are available.
Batteria solare agli ioni di litio
This is the most popular type in the PV world. A lithium-ion solar battery, as its name implies, uses lithium salt as the electrolytic solution. These types of PV storage batteries offer these benefits.
- Longer service life and shelf life
- High energy storage capacity in a small space
- Deeper discharge cycles
- Low maintenance requirements
The many advantages of the lithium-ion solar battery come at a cost, as these types are also the most expensive. Because they hold more charge in a small space, the batteries are best suited for residential or home PV systems.
Batteria solare al piombo
These use a diluted solution of sulfuric acid as the electrolyte. Apart from their solar applications, lead acid batteries find use in other fields, such as the automotive industry. A lead acid solar battery offers these advantages.
- They are low-cost options
- They offer excellent reliability
- They can be rapidly discharged
Lead acid solar batteries are more demanding when it comes to maintenance, requiring regular topping with water and even charging. They’re also prone to leaking and must be properly installed. They provide a stable backup, though, and fit domestic or commercial use.
Nickel Cadmium Solar Battery
These types of solar batteries are less popular than the other types. Nevertheless, they provide many benefits that cannot be found elsewhere, which include those listed below.
- They’re maintenance free
- It can last a very long time
- You can use these in harsh conditions such as high-temperature environments.
Being maintenance-free and long-lasting, a nickel-cadmium solar battery is a reliable backup storage device. But cadmium is highly toxic and must be handled with utmost care. So these batteries are rare in homes. They’re instead mostly used industrially.
Flow Battery for Solar Energy Storage
A flow battery is basically composed of two reservoirs that contain a water-based solution or electrolyte. These types of solar batteries provide several advantages.
- Can be fully discharged without damage
- It can last for a very long time
- Present no fire risk as the liquid doesn’t burn
The sheer size of flow batteries makes them unsuitable for small-scale use. So they are only found in industrial settings. They are also quite expensive and not suited for non-commercial applications. Other limitations include their low capacity and longer charging times.
Solar Battery Benefits
Solar batteries can be a crucial part of your PV system. With them, any excess energy that your installation produces can be of little help unless you have your system connected to the grid. But even then, you would need a backup in a situation like a blackout. The benefits of solar battery storage include:
- With a PV solar battery, you’re not dependent on the grid and can power your circuits even in a blackout.
- Your energy bills will reduce considerably since you’re not actively using the grid.
- Compared to generators, solar system batteries are a noiseless way to run your home or business, especially when utility power is not available.
- Depending on your location, you take advantage of the tax credits with complete solar installations.
Solar Battery Uses
Solar energy battery storage is primarily designed for PV installations. However, since solar energy systems are meant for use in different applications, you can use your battery in various situations. Popular solar battery uses include the following:
Solar Battery for Home Use
This is, by far, the most common application for these batteries. A solar battery for home use can be a single unit to power a simple circuit or an entire pack consisting of several batteries for the whole house.
When sizing a home battery, several factors come into play; the types of circuits or appliances to be powered, the rating of the solar array, and the most suitable battery technology for your needs. Most often, a home solar storage battery is a 5kW system.
Solar Battery for Camping
This is one of the most popular uses of solar battery technology, given the lack of access to the grid when camping. In most cases, these batteries are lithium-ion types for higher performance features, such as storing energy without taking up much space.
Note that a solar battery for camping can be a small portable type to power light and charge communication devices or a heavy-duty type to power an entire RV; it depends on the specific charging needs.
Solar Battery for Electric Fence
This is another of the most common uses of solar batteries. Solar-powered fences are popular with livestock farmers who want a cost-effective confinement solution or anyone looking to power an electric fence without incurring utility costs.
The size of a solar battery for electric fence applications depends on these factors: the fence size and amount of distance covered, and whether there’s vegetation to increase its drain. Generally, you need about 0.5 joules for every km or 1.3 miles.
Solar Battery for Garden Light
Outside the house, you could also install solar batteries to store power for your garden lights. These would charge during the day when solar power generation is at its peak and usage needs low, and then supply the stored power at night when needed.
Like with many other solar batteries uses, powering your garden lights using a storage system requires correctly calculating energy requirements. Typically, these are tubular batteries and are available in singles or packs.
A solar battery- or batteries- can be a worthy part of your photovoltaic installation. They allow you to capture and preserve the energy that the panels generate and use it when they do not provide enough power. You can use a single battery for more than a dozen, based on your requirements.