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Solar Panel Charge Time Calculator

If you’re looking for a solar panel charge time calculator, we’ve got that and more for you. We want to explain what the calculator can do for you and why it’s important to be able to use it. 

As you progress on your solar power journey, you’ll find that there are a few aspects you need to keep an eye on. 

We also cover some important facts that make your journey with solar power easier.

We’ve included an easy-to-follow example as we’ve found these really help to understand the math that can look complicated at first glance. 

We’re on a mission to make solar simple, and we’re sure this calculator does just that. We believe that everyone can benefit from solar power, but if you’re not sold, have a look at our solar energy savings calculator to find out just how much you’ll profit from a small investment.

We’ve got everything from the basics to mega setups and will happily guide you toward what’s best for your needs.

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Error: Select a battery type.
Optional: If left blank, we’ll use a default value of 50% DoD for lead acid batteries and 100% DoD for lithium batteries.
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Error: Select a charge controller type.
Estimated charge time:
Warning: We estimate that a solar battery charging setup with these parameters has a maximum charge current of . Many battery manufacturers recommend a maximum charge current of for lead acid batteries with this capacity. To maximize your battery’s lifespan, consider using a smaller solar panel or a bigger battery.
Warning: We estimate that a solar battery charging setup with these parameters has a maximum charge current of . Many battery manufacturers recommend a maximum charge current of for lithium iron phosphate batteries with this capacity. To maximize your battery’s lifespan, consider using a smaller solar panel or a bigger battery.

What Is a Charge Time Calculator?

A charge time calculator tells you how long it takes for your battery to recharge using energy from the sun.

solar panel charge time calculator

Those in the sunniest areas of the country should really look into getting solar energy as a way of becoming energy independent. Have a look at Texas’s solar panel cost and get started on your journey.

The charge time calculation also gives you an indication of how quickly your battery charges based on differently-sized solar panels. To do this, you enter the various wattages of your solar panel and you can see which one will charge your battery the fastest.

Solar Panel Charge Time Calculator: Why Do I Need It?

As we mentioned above, the calculation tells you how long it takes for your battery to charge using power captured by your solar panel. 

“Okay. But how does that help me?”

We hear you. It might seem like overkill, but this calculation can save your battery over time. 

If you allow your battery power to fall below 50%, it can cause it to degrade faster than usual. This means it won’t charge fully and you won’t be able to use it to its fullest capacity. Ultimately, you’d be wasting your money.

If your battery isn’t big enough to run all the things you want to without keeping it above 50%, you can use this calculation to measure how quickly it can recharge. If your battery can recharge faster than the appliance you want to use drains it, you’re safe to plug it in and use it.

If your battery can’t recharge fast enough, it’s safer to plug your appliance into a wall outlet to avoid battery degradation. Have a look at our solar depreciation calculator for more.

If you’re looking for a better quality battery for your setup, browse our LiFePo4 battery pack range for some affordable, durable options.

How Does the Calculation Work?

There are a few steps here, so stay with us. We’ve broken it down so you can easily follow along.

  1. Divide the solar panel wattage by battery voltage, giving you the input current (measured in amperes). 
  2. Multiply your above answer by 20%, and multiply that answer by 75%. This gives you the actual current.
  3. Multiply your battery capacity by 85%. This gives you the actual battery capacity of your battery.
  4. Divide the above answer by your actual current (your answer to point 2). This gives you the final answer. You now know how long it takes to charge your battery.

These values depend largely on the calculation of your solar panel’s efficiency, since the more energy it can convert to usable electricity, the less time it needs to charge your batteries.

To make it a bit easier to follow, here’s a practical example. The values you use depend on the components of your setup. You should be able to find them on the components themselves.

sok battery setup

If you’re having any issues, please feel free to contact us for assistance. We’d love to make your solar journey as seamless as possible.

Your solar panel inverter size will also affect how quickly your batteries charge, though the differences are minimal.

Here are the example calculations:

  • I = P/V
  • = 1000W / 12V

    = 83,33A 

  • 83,33 x 20% = 16,6A
  • 16,6A x 75% = 12,5A

  • 100AH x 85% = 85AH

  • 85AH / 16,6A = 5,12 Hours
  • This is for a small setup, but it works for a bigger one too. Simply plug in the relevant numbers and off you go.

    You can also make use of our solar load calculator to determine your needs and find all the solar & electrical calculators we created to help you plan, size and install your own solar power system here.

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