7 Things To Know Before You Buy Solar Batteries

7 Things To Know Before You Buy Solar Batteries

Last updated on December 12, 2023

A solar battery is a device used to store excess electricity generated for later use. Solar batteries are pretty popular for domestic use. Since they go hand in hand with solar panels, they often act as back-up when solar panels don’t produce enough electricity.

In addition, the benefits associated with solar batteries are incredible. Some of these benefits include being environmentally friendly, saving on cost, being noise-free, etc.

However, most people don’t know what factors to consider when purchasing solar batteries. Purchasing solar batteries, especially for the first time, can be tricky. For this reason, we have compiled a handpicked list of some vital factors to consider.

1. Capacity and Power

Capacity or size is the total amount of energy stored in the battery. The measurement of capacity is kilowatt-hours (kWh). While power is the current or electricity supplied by the battery measured by Ampere (Amps) or kilowatt (kW).

The capacity and power of a battery influence the time the battery will run. For example, a 10 kWh capacity solar battery with a 5 kW power will run for 2 hrs. The amount of power utilized in a day mostly depends on your electrical appliances. 


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    Heavy-consuming electrical appliances like fridges and microwaves tend to deplete your battery’s power quickly. This is because these appliances need high current. A battery with a high power rating and a low capacity rating supplies electricity for a shorter time. 

    To increase the time supply of electricity, you can add several high-powered batteries. If you have many electrical appliances, high-powered batteries are the best.

    A battery with a low power rating and a high capacity can supply electricity for extended periods. However, this applies where there are only a few non-consuming appliances.

    Knowing the capacity or power of a solar battery is super easy. All you have to do is check the capacity and power ratings. Two types of capacity are nominal capacity and usable capacity. Nominal capacity shows the total amount of energy the solar battery can hold. 

    On the other hand, usable capacity shows the actual amount of energy the battery can store. Most battery capacities range from 2 kWh to 10 kWh. There are also two types of power ratings, continuous and instantaneous. Instantaneous power rating is also known as 5 – minute or peak power rating. 

    As the name suggests, continuous rating shows the amount of current the solar battery can supply consistently. The instantaneous power rating shows the total amount of current the battery can supply at once. 

    The power ratings help you manage your electrical appliances better depending on their consumption. The power rating range of most batteries is between 5 kW and 7 kW.

    2. Battery Chemistry/Battery Type

    When considering the chemistry of your solar battery, check the elements it contains. The components contained in each battery are different. Moreover, the components determine certain things like storage.

    The main types of solar batteries are; Flow batteries, Lithium-ion batteries, and Lead-acid batteries. More and more solar batteries are being introduced regularly due to advances in technology.

    Lithium-ion batteries

    These are the most commonly used batteries, their central component being Lithium. Lithium-ion batteries convert stored chemical compounds to electrical energy. 

    It all begins when lithium ions release electrons. The ions flow from the negatively charged anode to the positively charged cathode. The electrolytes present in these batteries facilitate this movement. Lithium-ion batteries are used in almost any electrical gadget, from smartphones to electric vehicles. 

    The main types of these batteries are Lithium iron phosphate (LFP) and Lithium nickel manganese cobalt oxide (NMC). NMC batteries have numerous advantages like being more power-dense and cheaper. 

    However, they are prone to overheating, otherwise known as thermal runaway. Due to overheating, their duration tends to be shorter. There is also the risk of environmental pollution.

    LFP batteries, on the other hand, are long-lasting and lack environmental risks. LFP batteries also have coolers that prevent excess heat and cold. Coolers significantly reduce wear and tear. The only setback is they are very expensive.

    Flow batteries

    These batteries are also known as redox flow batteries. Flow batteries function using electrolytes. No metal compound is required to transfer electrolytes as they utilize liquids. 

    These batteries have not been in the market for long. However, they have good holding power compared to other battery types. Their lifespan is quite long too.

    Lead-acid batteries

    Lead-acid batteries are better than any other battery for off-grid functions. However, they take too long to charge. These batteries utilize lead components to function. The setup is two positive and negative plates suspended in an electrolyte.

    The electrolyte solution aids in transferring electrons from one plate to the other: the thicker the plates, the more durable the battery. Lead-acid batteries are well known for their utilization in vehicles.

    A more prominent type of lead-acid battery is the Tubular battery. Tubular batteries are found primarily in the city outskirts. They have a longer lifespan of 3 to 4 years than lead-acid plate batteries. They also have higher charging and discharging power.

    Lead-acid batteries can either be flooded or sealed. Flooded batteries have an electrolyte solution that must be topped-up every now then. Sealed batteries lack removal caps and don’t require any filling.

    3. Round- Trip Efficiency

    This is the amount of energy present in respect to the amount of energy used by the operating system of the battery. Some energy is continuously utilized within the battery when delivering the energy. It is essential to check the round-trip efficiency of a solar battery before purchasing it. 

    Always purchase a solar battery that has a high round trip efficiency. Ensure that you are not losing extra energy that your appliances could have utilized. For example, if the battery stored energy is 10 kWh but the energy delivered is 8 kWh. Then the round trip efficiency is 80%. The battery’s operating system utilizes 2 kWh.

    4. Compatibility

    When purchasing solar batteries, always check if it is AC coupled or DC coupled. You do not want to buy solar batteries that don’t match the wiring of your solar panel. In AC coupled storage, there are multiple energy changes. While in DC storage, the conversion of energy happens only once. The most common storage system is the AC coupled system.

    In AC storage, AC electricity is first converted to DC electricity. The DC electricity is usually utilized by the electrical appliances or serves other purposes. The remaining amount of electricity is later converted to AC and stored. The stored electricity will again be converted to DC during utilization.

    The multiple conversion of electricity consumes a lot of energy unnecessarily. AC coupled storage has several advantages, though. It can store the full amount of energy in solar batteries. 

    It does not matter whether or not the solar panels are accumulating enough energy. It is also easier to advance your solar system with an AC system than the DC system. The DC-coupled batteries store energy directly from the solar panels. 

    The only conversion occurs when the electricity is delivered to your electrical appliances. This is because most DC-coupled batteries have hybrid inverters. A Hybrid inverter is a device that converts AC to DC electricity. It functions in both your solar panel and solar battery, so there is no need to have two inverters. It is highly efficient as it saves on buying two inverters. However, you can purchase two inverters, one for the solar panel and one for the solar battery.

    If you already have a solar panel at home, you are likely to purchase an AC coupled battery. This is because most solar panels set up earlier were AC coupled. However, if you plan to purchase a solar panel together with a solar battery, it will likely be DC coupled.

    5. Duration and Warranty

    Duration is typically how long the solar battery will last. Different types of batteries have different durations.

    A warranty is a written document by the manufacturer promising to repair or replace an item. However, warranties have expiry dates. It would be best to try to get a good warranty before purchase. Warranties that have longer expiry dates are the best.

    When estimating the duration of a battery, there are certain factors you should consider. Does the battery have inbuilt protection from heat? If so, it’s highly durable. Overheating tends to burn out necessary cables leading to quick wear and tear.

    How many times does the battery charge and discharge? If the battery retains the charge for longer, it is likely to have a long lifespan. We all know retention of charge is an excellent indicator of durability in any electronic equipment. Other things to consider are expected years of operation and estimated throughput.

    Throughput is the production rate of the batteries; high throughput is an indicator of high durability. Low throughput is an indicator of low durability. Most solar batteries have a lifespan of 5 to 10 years. Lithium-ion batteries are more durable as they have 10 to 15 years.

    Lead-acid batteries are the least durable, with a lifespan of 5 years. On the other hand, Flow batteries can last up to 30 yrs. The life expectancies of these batteries all depend on how well you maintain them.

    6. Depth of Discharge

    Depth of discharge (DoD) is the capacity available for usage. It is the capacity you can utilize comfortably without straining the battery’s system. Flow batteries tend to have a higher DoD compared to other batteries. 

    They have 100% DoD, meaning you can utilize this battery until its charge is fully depleted. Lithium-ion batteries have a 90% DoD. Once you utilize 90% of its capacity, you should recharge it to prevent damage.

    7. Cost and Safety

    Before purchasing the solar battery you deem fit, consider the cost. Not just the cost of purchasing the battery but the installation cost too. DC-coupled batteries are more expensive to install than AC-coupled batteries because they are more complex.

    You should also ensure the solar battery meets all the safety requirements and criteria. Safety requirements should be adhered to when installing the battery. Solar batteries with coolers are safer as they can prevent overheating. LFP solar batteries are super safe due to the presence of coolers. To avoid accidents or hazards that may occur, you should also ensure that you purchase the solar battery from a qualified manufacturer.


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      Solar Batteries: Conclusion

      Solar batteries are indeed lifesavers; no more power outages. To top it up, you can take advantage of Tariff arbitrage; whereby you can recharge your battery when electricity rates are cheaper, thus significantly saving on cost.

      Furthermore, utilizing solar batteries helps conserve the environment by reducing carbon footprint. Genuinely, the positive impact of such batteries is enormous. Every individual ought to take advantage of solar batteries. Besides, you now know the factors to consider when purchasing these batteries.

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      E-Green Electrical

      E-Green Electrical is a top tier energy efficiency company based in Sydney. We focus on utilising government rebates to help reduce our clients energy consumption by installing energy efficient solutions. E-Green boasts a rich heritage within the realm of energy efficiency, consistently staying up to date with cutting-edge technologies to deliver optimal results for our valued customers.

      We don't just sell products and services; we also provides tips and information on how to help reduce energy consumption. We believe in using energy wisely and teaching others how to do the same. For E-Green, it’s important to share knowledge with the community. That's why we regularly write articles about saving energy, new government rebates available and increasing sustainability.

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