Do Solar Panels Drain Batteries at Night or Sitting Idle?

After going green with solar panels, many solar power enthusiasts wonder if solar panels drain batteries during the night or when they’re not being used, and we’ve got the answer and much more.

In this article, we’ll talk about how to prolong your batteries’ lives and talk about charge controllers—

let’s dive into it!

Do Solar Panels Drain Batteries At Night?

You have solar panels set up to charge up batteries, but do those solar panels drain battery life once the sun goes away?

The short answer is yes, solar panels do drain some battery life, and there are ways to prevent it by:

  • Proper wiring configuration
  • Battery type and
  • Current control

There are many appliances that solar batteries power, especially once the sun goes down, and solar panels happen to be one of them.

Although it’s not a lot of energy that solar panels use, it’s still significant and should be avoided to save money.

Fortunately, there’s a little gadget:

A solar charge controller to prevent this unnecessary battery drainage.

How Do I Prolong Solar Battery Life?

A simple trick is to buy rechargeable batteries rather than non-rechargeable batteries, as non-rechargeables don’t last nearly as long as rechargeable ones.

Just make sure that those rechargeable batteries are newly manufactured—the lifespan of batteries that sit in storage units for months don’t have nearly enough juice to be filled up to 100% in case of recharging.

Another method for saving battery life is to make sure all of your solar batteries are working on the

Keep Same voltage

Mixed voltages result in a shorter lifespan of batteries.

Checking to make sure that you’re charging your solar batteries correctly and that they’re set up properly results in longer battery life.

A higher amperage charges your batteries fast, and it’s tempting, but it’ll cause the battery’s lifespan to shorten and die out quickly.

Learn more: Series VS Parallel Solar Panel Connections

A final method is to charge a solar battery to its appropriate battery level. Every battery shouldn’t be charged fully—a good rule of thumb is to charge a battery to 80-90% of its full charge.

Of course, you don’t have the time to shut off the current or a way to know when a battery reaches its “point.”

That’s where solar charge controllers come into play.

Using A Solar Charge Controller

A solar charge controller is a device within a solar system that limits the current and power that goes into and out of the solar battery.

Using a solar charge controller helps prevent that unnecessary battery drainage, also known as reverse current, by the solar panels by controlling where the power goes and how much of it while ensuring that the batteries get filled up to the proper amount.

This will help increase performance and extend the battery life to its maximum lifespan.

Charge controllers are cheap, and they’re a must-have for solar systems. They don’t often come with many solar kits, which is why they will have to be bought separately, but it is vital.

Learn More: How to size your charge controller for a grid tied solar system

Do I Have To Shut Off Charge Controllers?

Since charge controllers run off of power that is stored from solar panels, they run themselves, so no, you don’t have to shut off your solar charge controllers, ever.

That is the most significant part of charge controllers—that they pay themselves off without any supervision or extra power input. And also, don’t worry about thinking that the solar charge controllers are taking too much power from your solar batteries.

Charge controllers are meant to take the most minimal amount of power to run themselves—you won’t even notice the small amount of power input that goes into the charge controller. Besides, the benefits of solar charge controllers far outweigh the disadvantages.

What Is Reverse Current Aand How Do I Prevent It?

Reverse current is when a current is going in the opposite direction of where it should be going. Reverse current often happens in cheap and faulty solar panels. With enough unwanted current, it can damage the solar panel, even though most solar panels are made to withstand some reverse current.

The cause of reverse current is more technical and happens primarily because of a wrong solar setup. With short circuits occurring because the strings used aren’t the same length, your solar design results in an open circuit terminal voltage much lower than other parallel strings.

Bypass, or string, diodes are tools that are connected in series with individual strings, which ultimately prevents reverse current. String fusses connected to other strings can also prevent reverse current, but the losses of string fusses are much lower than bypass diodes.

Key Takeaways

Here’s a list of key takeaways that are crucial from this article to save your solar batteries and solar panels:

  • Solar panels do drain the battery to an extent if set up incorrectly.
  • Buy newer, rechargeable solar batteries to extend your solar system’s life
  • Use the same voltage and power settings on your solar batteries
  • Invest in solar charge controllers—they’re literal battery savers
  • Solar panels may cause reverse current, but solar charge controllers can prevent this

Thank you for reading this short guide! Hopefully, you learned a thing or two that’ll help you save your battery and its lifespan. Solar systems may seem complicated, but they don’t have to be.

Kabeer Bhatia

Kabeer Bhatia has several years of experience camping and backpacking, and focuses more on the technical side of wilderness technology including solar energy.

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