Can You Add Batteries to Your Existing Solar System?

The short answer to your question ‘Can you add batteries to your existing solar system’ is yes, you can and if you add battery to solar system it will definitely be beneficial for you. The most fundamental advantage of adding a battery to your solar system is that you can use the excess energy produced by the system during the night time (when the sunlight is not available) or during any kind of emergency. 

If you add battery to solar system (existing ones) then you may have to go through some rewiring process to ensure the smooth operation of the entire solar system. You also need to keep in mind that some inverters may not function properly while adding a new battery and you might need to replace it with a new and compatible model. 

Why is it important to install batteries in a solar system?

In a solar system, batteries can be considered highly beneficial yet costly. If you are purchasing a battery-based inverter or a battery bank with a significantly high capacity then you may have to spend at least $5000 to $10000 in order to install it together with your solar system. 

Gas generators can be a cheaper alternative for you. The upfront cost of gas generators is extremely minimal and you can easily pair it up with the existing solar system. More importantly, the overall electricity produced by a gas generator can easily power up your entire home with ease. 

However, they will ultimately bring harm to the environment as well as you will need to constantly depend on fuel to run the generator. Not to mention, the level of noise you have to bear while the generator is running can be pretty difficult to get acquainted with.

On the other hand, if you add battery to solar system you may have to pay an increased upfront cost. Still, then your entire system will pretty much become maintenance-free, and utilizing the system will be much more flexible or adaptable. The excess energy produced by your solar panels will be stored in the battery and at the time of a power outage you will be able to use the stored energy to run the appliances at your house.

After the battery has been successfully installed and recharged it will work immediately whereas if you use any alternative energy source such as a gas generator it will take a significant amount of time to bring power back to your residence.

Type of solar battery systems available

Batteries can be attached to all kinds of solar systems (although the process can be a little different depending on the type of system and model). In case your solar system is battery ready it indicates that you have a solar inverter that is hybrid in nature and you will be able to join the battery directly. 

If your solar system or solar inverter is not hybrid in nature then you will need to install a battery with its own inverter. This feature will help you interface with your existing solar system, using the power from your existing solar system for charging and discharging. You should also remember that the hybrid inverters normally come with a ‘DC-coupled’ configuration whereas the independent battery inverters have an ‘AC-coupled’ configuration.

DC coupled solar battery system

DC-coupled battery energy storage system diagram. Source: RatedPower
DC-coupled battery energy storage system diagram. Source: RatedPower

In a DC configuration, the battery is installed and utilized in such a way that it consumes DC electricity directly from the solar panels. You can easily make use of the DC coupling system to add battery to solar system through a hybrid inverter and it is an extremely efficient method of attaching a battery to a solar panel. 

When the solar panels and battery inverter are coupled together into one unit then the system is known as a hybrid system. In this kind of system, the DC energy produced by the solar panels is directly stored in the battery, and when your residence requires electricity the hybrid inverter will directly convert the stored energy into AC electricity and power up your appliances. 

An advantage of using this process is that less energy will be wasted during the conversion process but the upfront cost will be slightly on the higher side because you will require a powerful battery as well as a powerful inverter. A DC coupling system can be a great option for people who have been using a solar system for quite some time and whose inverters are slowly giving up. 

AC coupled solar battery system

AC-coupled battery energy storage system diagram. Source: RatedPower
AC-coupled battery energy storage system diagram. Source: RatedPower

If you are not using a hybrid system then you can certainly opt for the AC coupled solar battery system. In an AC coupled solar system, the energy is not directly transferred to the battery from the solar panels. Instead, it stores excessive energy which gets either wasted or transferred to the nearby grid. 

The AC solar battery closely monitors the energy consumption of your residence and when the solar panels produce more electricity than the usually required amount it stores the energy in the battery. In this scenario, a special meter named CT meter is used to detect the additional electricity. 

Moreover, the AC solar battery can also detect the exact moment your home will pull energy from the grid and then it starts supplying electricity stored in the battery. Due to this particular feature, the AC coupled solar battery system can be installed with almost any kind of solar system. This system monitors both the excessiveness and shortfall in the supply of electricity and diverts the power supply accordingly. 

Going off-grid and protection from blackout

Although it is true that if you add battery to solar system it can help you save a lot of money at the same time it can also protect you from blackouts and function as a suitable option for turning off-grid. DC coupling and AC coupling are also applicable when it comes to off-grid batteries. 

Final words

If you want to save a significant amount of money on utility bills then solar batteries can be the perfect solution for you. Solar batteries also enable you to become self-sufficient and remain off-grid. If you already have a solar system then don’t worry because you can easily add battery to solar system.

However, you should also consider the current size and performance of your solar panels. If your solar system is relatively small with lesser capacity then it won’t be effective enough to charge your battery. In this scenario, you can increase the number of solar panels or you can also focus on the efficiency of the panels in order to easily charge the attached battery. 

Frequently asked questions

How much does it cost to add a battery to a solar system?

Batteries are the costliest part of the solar system and the starting price of a battery installation for a solar system is around $5000. With the increase in capacity, the price tag of the batteries will also increase. For example, large batteries such as Tesla Powerwall with a storage capacity of 13.5 kWh can cost you approximately $18000 including installation.

Can you mix old and new batteries for a solar system?

Mixing two different old and new batteries will not be a good idea for a solar system because putting together batteries of two different sizes, brands, voltages, types, etc. won’t let the system function properly. More importantly, this situation can also result in the failure of the battery bank. 

Is it worth adding a battery to solar panels?

Yes, adding a battery to your solar panel can be extremely helpful and beneficial in the long run. Although it is true that you can still utilize your solar panels without using a battery, having a battery attached to your solar system will ensure that you are less reliant on the grid of the utility company. When sunlight is not available you can use the stored electricity in order to power up your house. 

What happens to solar power when batteries are full?

In a solar system, the excessive amount of electricity generated by the solar panel is stored in a battery attached to the system. However, if your solar system is not connected to the grid then your battery can get overcharged after exceeding its capacity. As a result of overcharging the battery’s lifespan will be damaged. 

How long will a 5kW battery last?

If you are running a limited number of appliances at your house then a 5kW battery can last around ten hours. If you have a 5kW battery attached to your solar system you can easily use appliances like a fridge, lights, TV, etc. for at least ten hours. In case you are using heavy-duty appliances such as air conditioners then the power consumption will be higher and your battery won’t be able to last long. 

In this article, we have mentioned in detail the possibility of installing a battery with your existing solar system and what is the primary importance of using a battery with your solar system. We have also mentioned different types of solar battery systems you can opt for while installing a battery separately with your solar system and what kind of benefits you will receive from the same. The FAQs have been taken from the ‘people also ask’ section of Google.

Meet the Authors

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Brantley Edison is a highly experienced and accomplished writer in the field of solar energy. With over a decade of experience in the renewable energy industry, Brantley has contributed significantly to the growth and adoption of solar energy across various sectors. He has worked on several large-scale solar projects, including the design and installation of solar energy systems for commercial and residential properties.

Brantley holds a Bachelor's degree in Electrical Engineering and a Master's degree in Sustainable Energy. His educational qualifications and hands-on experience have given him a deep understanding of the technical aspects of solar energy, and he is well-versed in the latest trends and advancements in the industry.

Brantley's writing is highly informative and engaging, with a focus on educating readers about the benefits of solar energy and promoting sustainable practices. His expertise and contributions to the solar energy industry make him a valuable resource for those interested in adopting solar energy solutions.

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