What Happens to Solar Power When Batteries Are Full?

Whether living off-grid or as a full-time RV camper, a renewable energy source makes life easier. It’s an excellent option for environmentalists, survivalists, and pragmatists who know that having an alternative power source isn’t just a luxury—it’s a necessity.

Solar power generators use batteries to store the electricity they generate for later use. But what happens to that power when the batteries are full? Does it go to waste? 

Here, we look at how solar power systems work and the critical role that their batteries play in storing power. Whether you keep that power on standby, sell it to the grid, or float it to other devices, here’s what you can do when your battery is at maximum capacity.

What Happens When Solar Power Batteries Are Full?

Solar power systems use batteries to store solar energy. However, if the power generated exceeds the solar battery’s capacity, it can overcharge the system. An overcharged solar system can severely damage a battery’s life. 

As soon as a solar battery reaches full charge, the inverter and charge controller must step in to mitigate risks by handling excess power. They can do this in three ways: push it back into the panels for power loss, back into the grid for credits, or force a dump load. 

Off-grid systems typically include solar panels, charge controllers, battery monitoring systems, and batteries. Solar panels collect energy, which passes through a charge controller to batteries. Battery monitoring displays the battery bank’s charge level. 

The charge controller protects batteries and solar panels by managing the energy flow. Battery charge controllers stop electricity flow when they signal that batteries are full. 

Many solar power systems incorporate inverters and charge controllers to ensure trickle charging and redistribute excess charges. However, you can also return power to the grid. Surplus energy fed back into the grid is available for use by community members who cannot access solar panels or other renewable energy sources.

A New Way to Stay Charged—EcoFlow DELTA Pro Smart Battery

The DELTA Pro Smart Battery from EcoFlow mitigates the risks outlined above by giving you control of your battery charge levels and recharge rate. With this extra smart battery, not only can you double the capacity of your DELTA Pro Solar Generator from 3600Wh to 7200Wh, but you can also prevent overcharging issues.

The DELTA Pro smart battery connects to the DELTA Pro portable power station or solar generator. Connect two, and you can achieve up to 10.8kWh for a robust off-grid home backup or full-time RV living. A sleek LCD screen lets you check the battery’s charge percentage, recharge time, and more. Plus, you can use the EcoFlow app to check the battery’s status, no matter where you are. Once you charge it to maximum capacity, the battery will hold its charge for up to one year after a full charge. Power doesn’t get more convenient or reliable. 

How to Know When Your Solar Batteries Are Fully Charged

Several options are available to check the charge level of a battery within a solar energy system. 

Intelligent energy storage solutions like the EcoFlow Smart Battery feature display screens that indicate the battery’s charge based on its voltage. 

Some inverters display the battery’s charge level on their screen, so you can tell if it’s charging or full. Inverters without display screens may have a warning or indicator system to tell you the battery status. 

You can also purchase meters to check the charge level. Look for a voltmeter, hydrometer, and multimeter. 

  • Voltmeters are instruments that measure electric potential. To check the charge of a battery, connect your voltmeter to the red and black ports. If you want an accurate reading, the battery shouldn’t have delivered electricity for the last few hours.
  • Hydrometers are only used for flooded lead-acid batteries since it requires measurements from the liquid inside. 
  • A multimeter can measure voltage, current, resistance, and many other things about your battery’s condition. 

What to Do if Your Batteries Regularly Become Full 

If you find that your solar batteries are regularly becoming full, you can offset that extra power and put it to good use. 

Sell One of Your Panels 

You may be connecting too many solar panels for your energy needs. You can sell excess panels in many marketplaces and local swap pages. There is no doubt that solar panels hold their value well, and you might be surprised at how quickly people will snatch them up. In many cases, worn or outdated solar panels can be recycled or reused

Purchase Additional Batteries or a Higher Capacity Solar Generator 

Purchasing a higher storage capacity solar generator will also help store more power. For example, EcoFlow’s DELTA Pro Solar Generator stores significantly more energy than the generators from EcoFlow’s River 2 series. The River 2 series is intended for camping and other off-grid activities where portability is crucial, while the DELTA Pro is an ideal home backup power solution.

Many solar generators also allow you to purchase extra batteries to increase your solar power storage capacity.

Ignore It 

It’s possible to do nothing with your full battery until you need the extra power. Downsizing or upsizing may not be worthwhile if excess power is only available during the sunniest days. 

Compare your power usage with the capacity of your battery bank. It may be best to keep the setup unchanged if they are well-matched. On rainy or overcast days, you may need that extra energy. 

Use More Power 

You can use extra power for future needs, such as:

  • Charging tools 
  • Cooking food 
  • Refrigerating food
  • Dehydrate food for storage 
  • Run an AC unit for longer

Where Does Excess Solar Power Go When Batteries Are Full? 

The direction of the power depends on your setup and whether you have a grid or an off-grid system. 

An on-grid solar system sends AC power to your appliances first. If the home doesn’t have enough load to use all the electricity, it’ll feed the remaining power back into the grid.

In off-grid applications, the inverter receives extra electricity and converts DC into AC power. Any appliance connected to the circuit can then use this power. With EcoFlow solar generators, the battery will stop absorbing energy once the battery has reached full capacity to prevent any possible damage. 

Where Can I Float Excess Energy? 

There are two ways to handle excess power. You can let it discharge from your battery, wasting the energy and potentially damaging your battery in the long run, or you can float it to appliances and devices to reduce your on-grid power consumption.


Typically, solar panels generate power for devices and appliances that require electricity immediately but not continuously. If you’re generating enough solar power that your battery consistently reaches capacity, consider using the excess energy to run ice and refrigeration systems. 

The Electrical Grid 

With many fixed solar power systems, you can send excess energy to the electrical grid if your solar panels have collected enough energy to power your home and charge your battery. For many people, this is a significant reason they use solar energy.

The electrical grid distributes electricity to homes and businesses. Without solar panels, your home depends on the electrical grid.

Owning portable solar panels and a solar generator allows you to live on or off the grid. You don’t have to worry about running out of solar power while on the grid. Electrical grids serve as backups when an on-grid solar system fails.

You can install a net meter on the grid to record your solar energy use. Excess solar energy is directed back to the grid through this meter. Homeowners can earn credits for the extra energy they generate, which can be used on a future bill, saving them some money.

Air Compression 

Air compression machines are the next dump load for an excess charge. Intelligent on-grid solar panel systems will send excess power to air compression devices to store energy for later use.


Depending on how much additional energy your solar system generates, you can use it to assist with home heating. Both heated air and heated water are ways to expend extra energy. For example, you’ll want to use the heater more frequently in the winter to keep the home warm and cozy. 


Some solar batteries are at risk of igniting and overheating — or at the very least reducing their lifespan — when overcharged. 

Select a solar system that takes the hard work out of monitoring battery performance, adding additional capacity, and efficiently handling excess energy. Shop EcoFlow today for solar energy that’s smart and efficient.

EcoFlow is a portable power and renewable energy solutions company. Since its founding in 2017, EcoFlow has provided peace-of-mind power to customers in over 85 markets through its DELTA and RIVER product lines of portable power stations and eco-friendly accessories.


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