What Happens to Excess Solar Power When Batteries Are Full?

SolarJerry Lee

Do solar panels keep charging when batteries are full? Does it hurt if solar panel keeps charging as the batteries are full? Some people may be confused and worried about it. In this blog post, we shall explore the secret of solar battery chargers. In the end, you will get a clear answer to these queries, as well as what you can do when the batteries are fully charged by solar panels and reach the maximum capacity. Let’s get started now!


What Happens When Solar Power Batteries Are Full?

The solar power system is a new type of power generation system that can convert sunlight to electricity energy, using the photovoltaic effect of semiconductors. Solar power system stores solar energy with batteries. There are two different types of solar systems, on-grid solar power systems and off-grid solar power systems. Let’s see what will happen to the two types of solar power systems when the batteries are fully charged.

When Off-Grid Solar Power Batteries Are Full

The off-grid solar systems are helpful for those who live in remote areas where the grid is not available. It converts the solar energy to electricity and stores it in the solar batteries. Once the battery reaches its full capacity, it will stop converting. If the solar power battery gets full or 100% charged, it may overcharge the solar system. No doubtably, an overcharged solar system will damage the battery life span.

If you are using old lead acid batteries, it could be dangerous and even lead to explosions. The modern lithium batteries are safer than the lead acid batteries, for they will not discharge hydrogen gas normally. But the thermal runaway is a potential risk of modern lithium batteries. So the battery safety is the first criterion for selecting a battery.

When Grid-Connected Solar Power Batteries Are Full

The on-grid(or grid-tired) solar systems connect to the electric grid. The on-grid inverters convert the solar panels’ direct current to alternating current. When the batteries are overcharged, the inverters will send the excess energy back to the grid.

When the solar power battery continues charging as it gets 100% full, the inverter and controller need to take steps to deal with the excess power. They normally send the excess power to the grid, or shift the electricity load of your home.


What to Do if Your Batteries Regularly Become Full?

If you have noticed that your batteries regularly reach full, you can try the following practices to offset more excess battery power.

Discard or sell one of your panels:

Perhaps more solar panels are not good. For those who have multiple solar panels, it is wise to set aside or sell some of your solar panels. Do not worry. Solar panels hold their values well. Once the solar panels are hung on a second-hand market, they can be sold out quickly.

Purchase a higher capacity solar batteries:

Solar batteries always get fully charged? Anker 767 Portable Power Station can be a great option to deal with this. This long-lasting portable solar battery charger, with a capacity of 4096Wh, has a long lifespan of 10 years.

How to Know If Solar Battery Is Fully Charged?


As your solar batteries go fully charged, some inverters with the battery display screen will show the battery status. For those without a battery screen, they may give you a warning that shows the battery is fully charged. If none of those are available, you may need to purchase some meters to see the charged status. There are some options that will tell you that your solar batteries are fully charged:

  • Voltmeter: It is an instrument for measuring voltages of direct or alternative electric current. To use this tool, you should connect your voltmeter to the black and red ports. If you want an accurate reading, please keep the battery not charged for a while.
  • Hydrometer: It is only suitable for the flooded lead-acid batteries, and it measures the liquid inside.
  • Multimeter: Some homeowners may benefit from the use of a multimeter. Whether you are using an analog multimeter or a digital multimeter, it gets the readout which shows if your solar batteries are fully charged or not.

How to Make Use of the Excess Solar Power When Batteries Are Full?

It is a common phenomenon that solar panels will produce the excess solar power when the batteries are full. It may be a waste of resources if you don’t know how to use the excess solar power. Here we’ll teach you how to make full use of the excess solar power, and you can try the flowing methods:


If the power of your solar panels is large enough, you can use the excess power to run a cooling machine, or refrigerator.

Air compression

For the on-grid solar panel system, you can send the excess power to air compression devices. With the Compressed Air Energy Storage (CAES), you can convert the electricity to compressed air and store it.


You can use the extra energy to power the home heating devices. For example, you can use the extra energy to heat the water, fish tank, etc.

Final Thoughts

Overcharged solar power batteries may cause a series of problems, even leading to a reduced lifespan. Please be at ease. We have introduced different ways to make use of the excess solar power when the batteries are full. Some people choose to change to a higher-capacity solar battery, while others may leave it alone. Finally, it depends on your preferences and demands. However, one thing needs to be noticed: be sure to purchase a good solar battery for security considerations. It can be a wise choice to make better use of the excess solar batteries and build a healthy environment in the bright future!