Solar power is rapidly replacing alternative means of electricity generation. The generation of green electricity and elimination of high electricity prices make solar panels the best electric power option. As such, questions like ‘what is solar battery’ have become common.
Understanding the basics of solar batteries can help make a better decision when buying one. Additionally, knowing about the operation of a solar battery can make it last significantly longer than expected.
This article will outline all the necessary solar battery storage system details. You will learn about many important things, such as the cost of a solar battery and how to choose one.
What is Solar Power Storage Battery?
Solar battery storage is a solution to store the power generated by solar panels. Solar panels generate electricity only in the presence of sunlight. There is a lot of excess solar energy that cannot be utilised completely by a common household. Solar batteries store this excess solar energy and provide electricity when solar panels are not producing electrical energy.
For instance, solar batteries will store solar energy during the day. Solar batteries will power the household at night when there is no sunlight. Therefore, there is solar energy available during the day and the night.
When were solar batteries invented?
The first solar battery was invented in 1954. DM Chapin, CS Fuller, and GL Pearson have the credit for inventing the first solar battery. This battery was a simple array of small silicon chips. The silicon chips would create electrical energy when placed in the sun.
How Do Solar Batteries Work?
A solar battery works similarly as the batteries in a smartphone or an Uninterrupted Power Supply (UPS). Solar panels are designed to create electricity when sunlight falls on them. The panel comprises special materials that release electrons in the presence of sunlight. The electrons then flow through the circuit and create a lot of electricity.
The battery is connected to this solar panel grid. The electricity generated powers the household. The battery is present in parallel to the circuit, so any extra charge goes directly to the battery storage. Solar batteries are configured so that they will store charge only after the household’s electrical requirements are met. In this manner, a solar battery saves electricity that would otherwise go to waste.
Components of a Solar Battery
The main components of a solar battery are:
- Casing: The battery casing is the outermost part of the battery that is visible to the eyes. The casing does not affect the internal battery chemistry and reactions. However, the casing protects the internal components of the battery and keeps it sealed.
- Electrodes: Every battery consists of two electrodes- cathode and anode. These electrodes are terminals that complete the electrical circuit and provide a path for current transfer.
- Electrolyte: The electrolyte is the medium that separates the two electrodes. Electrolytes are electrically conductive and provide a path for the flow of ions.
- Separator: A separator is a barrier between the two electrodes inside the battery. It acts as a protection to eliminate contact between the two electrodes. The electrolyte ions can pass safely through the separator.
- Control Circuit: The control circuit monitors the charging and discharging operation of the battery. The control circuit is essential to ensure safe battery operation. A good control circuit prolongs the lifespan of the battery significantly.
- Terminals: Terminals are external to the battery. These connect the battery to the electric circuit, which the battery will power. The charging current also travels through the same circuit to the terminals.
Solar Battery Connection Configurations
There are two types of connections between the solar battery and circuit: AC coupling and DC coupling. Each of these configurations has its advantages and drawbacks. Let us go through them one by one:
AC Coupled System
An AC-coupled system has an inverter between the solar panel and the household circuit. The inverter converts the DC power generated by solar panels to AC power used by household appliances. The battery has another inverter connected to it. The excess power flows to this inverter, gets converted back into the DC, and is stored in the battery.
The battery becomes active when the solar panels are not generating electricity, such as at night. The stored energy in the battery is released in DC form. The battery inverter converts it to AC and supplies it to the household.
The power inversion takes place in three electric flows:
a.) DC to AC from solar panel system to the household circuit; Inverter 1
b.) AC to DC from household circuit to battery storage; Inverter 2
c.) DC to AC from the battery storage system to house appliances; Inverter 2
Since the battery has its own dedicated inverter, it can also store grid electricity. Conversely, the battery can also provide power to the grid electricity due to the inverter.
Advantages of AC Coupled System
AC-coupled battery storage system can provide power to the grid and take power from it. It gives the household the benefits of taking electricity rate arbitrage. The electricity costs are thereby significantly reduced during the unavailability of sufficient solar power.
Additionally, AC coupled battery storage system has a modular design. Making any upgrades or modifications to the system is quite easy.
Disadvantages of AC Coupled System
The main disadvantage of an AC-coupled system is its low efficiency. There are three instances of power inversion in the circuit. Every power inversion involves some amount of loss. This makes the AC-coupled systems less efficient.
DC Coupled System
A DC-coupled system has a one-inverter setup. There is no dedicated inverter for the battery. The solar panels power the battery storage directly with DC. The inverter is present between the household and the battery. When the house requires solar power, the battery discharges it in DC. The inverter turns it to AC and supplies it to the house.
In essence, only one inversion process occurs- DC to AC from the battery to the household.
Advantages of DC Coupled System
The major benefit of a DC-coupled system is efficiency. There is only one inversion process of DC to AC. Therefore, the power losses in this method are minimum. This makes it the more efficient coupling method.
Disadvantages of DC Coupled System
DC-coupled systems have very complex setups. Any future modification to the system is also difficult. Additionally, the usability of the solar battery with the grid requires an additional inverter. This will increase the electrical losses, nullifying the benefits.
How Do Solar Batteries Differ From Other Batteries?
Solar batteries differ considerably from other types of battery storage, such as car batteries. Options like car batteries are designed to provide an initial surge of current. However, solar batteries are designed to provide constant current for a long duration.
Additionally, solar batteries also differ from other deep-cycling battery options. Solar batteries are designed to withstand fluctuating currents. These batteries are also capable of charging to a higher voltage capacity.
What are the Different Types of Solar Batteries?
There are many options for solar battery chemistry. Each battery chemistry has its own unique characteristics, advantage, and disadvantage. Here is a brief analysis of the different types of solar battery chemistry:
Lead Acid Batteries
The lead acid battery is the oldest type of battery technology still used today. These have the worst performance and lifespan among any solar battery. The only factor in their favour is their lower cost.
Lead acid batteries contain a liquid electrolyte that requires top-up after some time intervals. Lead acid batteries are notorious for failures and short cycle life. These batteries are usually expected to last up to 500 cycles. They commonly fail after 300 cycles, so they are least preferred in the solar battery storage system.
Lithium-ion battery became a significant improvement over the conventional lead acid battery. The electricity generated and stored in this solar battery is due to the lithium ions flow.
The huge popularity of these batteries led to the emergence of many different variations. The variations have unique electrodes. Some common lithium-ion batteries are Lithium Iron Phosphate (LiFePO4), Lithium Manganese Oxide (LiMn2O4), Lithium Cobalt Oxide (LiCoO2), and Lithium Nickel Manganese Cobalt Oxide (LiNMC).
Lithium Iron Phosphate Batteries
Lithium Iron Phosphate battery is a very specific type of lithium-ion battery. It is abbreviated as LiFePO4 or LFP battery. It consists of a graphite anode and LiFePO4 cathode.
LFP batteries are a significant improvement over conventional lithium-ion batteries. LFP battery easily provides a lifespan of over 10 years in optimum health. The charge retention and depth of discharge are also exceptional. This is why most users replace a lithium ion battery with an LFP battery in almost every application.
Nickel Cadmium Batteries
A Nickel Cadmium battery is used for specific applications of solar batteries. Generally, Nickel Cadmium batteries find usage in areas where only a small amount of power is required. A common example of these batteries is the solar lights used in parks and gardens.
A flow battery has a very unique structure. It consists of chemical components dipped in liquid tanks that undergo chemical reactions. Instead of a cathode and anode, there is a catholyte tank and anolyte tank. Flow batteries have a good cycle life when compared to lithium-ion batteries. However, these batteries are not energy efficient. The losses in these batteries can be over 50%.
Sodium battery stores and disperses current in the form of Na+ ions. These batteries are identical to Lithium-ion batteries, with Sodium replacing Lithium. The scarcity of Lithium increased the popularity of Sodium batteries. However, the energy density of these batteries is quite poor. They also have a smaller number of charge and discharge cycles.
Nickel Iron Batteries
Nickel Iron Battery is also known as NiFe battery. The electrodes are made of heavy plates. The negative plate is Iron. The positive plate is Nickel Oxide-Hydrochloride. Potassium Hydroxide electrolyte is used. These batteries are sturdy with good safety standards. However, they are costly to purchase. Their charge retention and specific energy are also poor.
What is the Best Solar Battery?
Lithium Iron Phosphate battery is the best solar battery. The technology behind the LFP batteries makes them ideal for solar battery storage than any other alternatives. For instance, LiFePO4 batteries have a depth of discharge of 98% to 100%. This means you can use the entire solar power stored in the battery without waste. The discharge depth also means a longer running time for the battery.
LFP batteries last upward of 5000 cycles with good maintenance. This provides a better value for money than any other solar battery storage options. These are just a few reasons users prefer LiFePO4 batteries with solar panels.
Application of Solar Battery System
It is possible to use a solar battery for any electrical power requirement. The most common uses of solar battery storage are:
More and more house owners prefer solar power over conventional electricity grids. Solar power is a considerably cheaper option for house owners that can provide unlimited electricity. Besides powering all the electrical appliances of the house, solar batteries can also charge an electric vehicle.
Solar microgrids are a collection of solar panels that power multiple households or entire communities. Solar microgrids power homes, businesses, farms, irrigation systems, schools, street lights, and hospitals. Their major use is in remote locations that do not have access to a main power grid or face a lot of outages. Solar microgrids use multiple solar batteries.
Solar panels and battery storage is a great option for malls, industries, and other commercial setups. Commercial setups are heavy users of electricity. Using solar power lowers cost of operation for businesses and frees up the load from the grid.
Solar batteries are common in housing complexes and associations. The individual houses pay a portion of the cost of setting up the solar power plant. The monthly bill for the households is a very meagre amount.
Secondary Support for Power Grids
Electrical power grid often uses solar farms and batteries as a support mechanism to handle the peak load. Solar batteries as a support mechanism reduce strain on non-renewable energy-producing grids.
Can a solar battery be used for grid backup power?
Yes, a solar battery is a great option for grid backup power. Many grids use this feature to avoid power outages in peak hours. Using solar battery as grid backup power also reduces power generation costs.
Pros and Cons of Solar Battery
A solar battery has a lot of advantages for every type of user. At the same time, there can be a few disadvantages to this technology too. Let us go through each one by one:
Advantages of Solar Batteries
- Clean Energy: Solar power is the cleanest source of energy. It doesn’t require any fossil fuels. At the same time, there is no need to set up large-scale infrastructure like a dam. This reduces the carbon footprint of the overall power generation process.
- Independent Electricity: Solar batteries provide complete energy independence from power grids. The user controls how and when to use the solar power system. There are no unexpected power outages, unlike the electrical grid.
- Electrical Grid Arbitrage: A solar battery is not only used for household power consumption. It can also provide electricity back to the electric grid. This helps in lowering the time of use tariffs for electricity. House owners have to pay only a tiny fraction of the electricity bill, if at all. Solar panels and solar battery storage mostly produce all the energy.
- Solar Power During Non-Availability of Sun: Solar panels depend on sunlight to generate electricity. Therefore, the electricity produced drops to zero during the absence of sunlight. Therefore, households have no solar power during bad weather or at night. Solar battery storage solves these issues completely. It can store the excess energy generated by solar panels and provide it during bad weather and nighttime.
- Power Backup: Solar batteries are perfect as backups in a power outage. This provides a cost free alternative to other backup options. Additionally, conventional power backups operate for a very limited time. However, solar battery storage has prolonged usable capacity.
- Avoiding Energy Wastage: Without batteries, all the excess generated electricity by solar panel system will go to waste. Solar battery storage avoids this wastage by storing excess energy and using it when required.
Disadvantages of Solar Batteries
- Investment: Solar batteries require an initial cost for the equipment. However, their operating costs are almost nil. This makes them a very cost-effective option.
- Maintenance: Solar batteries require a proper maintenance schedule to prolong their lifespan. Without maintenance, these batteries can reduce their power output and cycle life.
- Lifespan: Solar batteries don’t last forever. They will need replacement after a while. However, choosing the right battery can mean a longer lifespan. For instance, while conventional lithium-ion batteries last around 4 years, a good quality LiFePO4 can last 15 years.
- Efficiency Losses: Solar battery storage does not store all the power generated by the solar PV system. Some of the energy is lost in the conversion process.
What is the Cost of a Solar Battery?
The cost of a solar battery starts at £550 and can go up to £3000. Many factors influence the cost of the system. The most important parameter is the capacity of the battery you are getting. The capacity of the battery depends on the requirement of the household and the output of solar PV panels.
How Much Energy Can a Solar Battery Store?
A 48 V 100 Ah solar battery will have stored energy of 4800 Wh (4.8 KWh). The stored energy capacity on the solar battery is usually not rated in KWh. Instead, solar batteries use Ampere hours (Ah) as the capacity rating.
However, this capacity can be easily converted to Wh. To do that, multiple the Amp hour with the battery’s rated voltage.
Wh = Ah x Voltage
For a 12 V 216 Ah battery,
Wh = 12 x 216 = 2592 Wh = 2.592 KWh
How to Choose a Solar Battery?
Choosing the right solar battery requires consideration of several factors. These factors are:
- Capacity: Capacity is the primary factor when considering a battery. Calculate the wattage of the appliances at your house. Multiply it by the number of hours the battery needs to power these appliances. This is the Watt hours rating you require. Multiply it by 1.2 to take into account the energy losses.
- Depth of Discharge (DoD): DoD depends on the type of battery. If you want a completely usable battery, opt for a LiFePO4 option. If you go with lead acid batteries, you will need double the capacity because they have only 50% depth of discharge. This means that you can use only half of the capacity of lead-acid batteries.
- Efficiency: A battery with a good efficiency will ideally store all the power it receives and provide the same when required. Poor efficiency means that it will store electricity with certain losses. Good quality branded batteries like Eco Tree Lithium are the most efficient.
- Lifespan: It is better to opt for a longer lifespan to ensure fewer replacements. Options like LiFePO4 batteries easily last for 15 years. This ensures a better return of your investment.
- Battery Type: There are many different types of solar battery chemistries. Every type comes with its benefits and shortcomings. Choose the appropriate battery based on your requirements.
- Cost: There is a wide price bracket for battery in every segment. Batteries with better features can come at a higher cost. Find the perfect balance between cost and features.
- Compatibility: Ensure that the battery is compatible with your solar power system. Solar batteries work on the same voltage as the panels. Therefore, check the solar system voltage before buying the battery.
- Charging Time: The charging time of the battery depends on the charge rate. The charge and discharge rate are mentioned on the battery. Choose this rate according to the available sunlight time in your location.
- Safety: Solar batteries have a large volume of energy stored. Therefore, it is important to prioritise the safety protocol of the system.
- Maintenance: Choosing a battery with a lower maintenance schedule can save a lot of potential trouble. For this purpose, avoid options that need electrolyte top-up or venting.
- Size: The dimensions and weight of the battery should fit into the required area in the solar battery systems.
- Reliable Brand: A good brand means sturdy construction and quality parts. Additionally, branded batteries also ensure you get any support you require.
How Long Do Solar Batteries Last?
A solar battery can last anywhere from 3 to 25 years. The lower limit is for lead acid batteries and other batteries of poor quality. The higher limit is for LFP batteries from reliable supplier like Eco Tree Lithium.
Are Solar Batteries Eco Friendly?
Yes, a solar battery is the most eco-friendly option for energy. It ensures you do not use fossil fuels in your household electricity requirements. Additionally, the batteries themselves can be completely recycled.
Is Buying a Solar Battery Worth It?
Buying a solar battery is completely worth the money. However, to ensure cost-effectiveness, ensure that you buy a good-quality battery. Better solar batteries cost more, but they will provide a better value for money.
Can You Store Solar Battery In Your House or Garage?
You can store solar battery in your house, garage, or any other location you prefer. An important thing regarding safety is the battery build quality. Ensure that you have a battery from a reputed manufacturer. This will eliminate any chances of hazardous occurrences.
The surge in electricity costs means that solar power systems will be the preferred technology of the future. Solar panel battery storage has tremendous benefits. The shortcomings of the technology, if any, can be easily overcome. The best part is that solar batteries only use the excess electricity from the solar panels. Therefore, you can power up any appliance with solar battery and enjoy tariff-free electricity.