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How Fast Do Portable Solar Panels Charge?

Portable solar panels are becoming increasingly reliable and efficient. Whether you prefer handheld solar panels, suitcase solar panels, or any panel in between, it’s important to know the average charging time. After all, it directly affects how many panels you need, what you can charge, and more.

Portable solar panels take between 8 to 50 hours to charge, depending on the wattage, battery size, sunlight availability, and more. Avoid charging anything with the solar panel’s battery until it’s fully charged to prevent the charging time from taking much longer.

Throughout this article, we’ll explain how quickly your portable solar panels will charge, what affects their charging speeds, and why your panels might be charging slower than usual.

What Affects the Charging Speed of Portable Solar Panels?

Portable solar panel charging speeds are affected by how well they absorb sunlight. Anything hindering the solar panel will prevent it from charging quickly. The charging rate is determined by how many watts are absorbed and produced to charge the internal or external battery connected to the panel.

Here’s a list of what influences your portable solar panel charging rate:

  • Best Buy explains that sunlight availability is one of the most important parts of determining how fast your portable solar panels will charge. The more coverage your portable solar panel has, the quicker it’ll charge. This also means overcast, cloudy weather will affect the charging rate.
  • Portable panels with higher voltage production will charge faster than low-voltage or low-wattage panels. Look for a panel that ranges between 10 volts to 20 volts or more. You’ll likely come across portable solar panels with as little as 5 volts, but they can take more than a day to charge.
  • Monocrystalline solar panels charge quicker than polycrystalline solar panels. Monocrystalline panels use a series of solar cells that absorb sunlight much more efficiently, which results in a significantly quicker charging rate. Furthermore, they’re better in all weather conditions, making them the go-to choice for everyone.
  • Wider, longer panels typically absorb more sunlight because there’s more exposure. This is why most pocket-sized solar panels either unfold into multiple panels or don’t produce enough energy each hour. Longer, wider panels are often thinner, especially if they don’t have a built-in battery.
  • Scratch-resistant panels last longer, preventing the charging rates from slowing down. Make sure you choose high-quality panels with added protection to prevent them from slowing down. Monocrystalline panels don’t scratch as easily as polycrystalline panels, which is another reason you should choose them.

As you can see, many things change how quickly your portable solar panels charge. Whether you’re using multiple portable solar panels or a compact battery, several factors change if your panel will reach a complete charge within a day. In most cases, they can charge much quicker. Read on for more information about charging rates and how long it takes.

How Long Does a Portable Solar Charge Take To Charge?

Portable solar panels can charge in as little as 8 hours. The charge rate refers to how quickly the panel can charge the battery. Most portable solar panels use external batteries, but some have internal batteries. Internal batteries charge slower because they reduce the panel’s power production.

Suitcase Portable Solar Panels

Renogy states that most portable solar panels can charge 12V DC batteries in eight hours or more. Remember that this estimate assumes that your solar panels are exposed to direct sunlight. Consider the panel’s voltage to determine how quickly it’ll charge the deep-cycle battery (or Li-Ion, depending on your portable setup).

The Renogy 200W 12V Portable Solar Panel comes with battery clips and a charger showing how much energy is consumed and produced. It comes in multiple sizes, all of which fold into a compact suitcase to let you bring it wherever you go. These panels also have locking legs to help you point them directly at the sun for maximum coverage.

Handheld Portable Solar Panels

On the other hand, Innovate Eco claims that most handheld portable solar panels charge in around 50 hours. These panels take much longer to charge because they’re usually small-framed, low-wattage, low-voltage, polycrystalline panels. In other words, they have all the reduced qualities compared to high-quality portable solar panels.

The Hiluckey Solar Charger is a foldable pocket-sized solar panel that charges in as little as eight hours. However, it can hold a full charge for up to nine days. This 25000 mAH solar panel has four panels, but they fold over each other, so you can put them in your pocket. It also has multiple USB ports to charge your favorite devices.

If you’re interested in compact, portable solar panels, you’ll likely come across 10W, 20W, and 30W foldable panels. These low-cost panels might not be as efficient as the Renogy suitcase solar panel, but they can be very useful in a pinch.

Many people store them in their glove compartments for emergencies. Proceed to the next section to determine how long they take to charge completely.

How Long Does a 10-Watt Solar Panel Take To Charge a Phone?

If you have a 10-Watt solar panel, you might wonder how long it takes to charge a phone.

A 10-watt solar panel takes 1.5 to 3 hours to charge a phone. This is because the panel doesn’t have a battery, which means the energy goes directly into the phone, tablet, or computer. You can determine how long the panel takes to charge by multiplying the wattage by the hours it charges.

Follow this formula to know how quickly your phone will charge with any portable solar panel:

  • Find out how many watt-hours your smartphone requires. Most smartphones range between 12 and 15 watts, but it’s important to know the exact watt-hours of your device’s make and model.
  • Determine how many watts your portable solar panel charges hourly. For example, the aforementioned 10-watt solar panel produces 10 watts per hour. The wattage listed on the panel is always how many watts it creates hourly, not instantly.
  • Divide your phone’s watt-hours by the watt production of the portable solar panel. Using the 10-watt panel example, your panel will charge a 15-watt smartphone in 1.5 hours. Again, this number assumes your portable solar panel has direct sunlight throughout the charging process.

This formula can also determine how quickly any portable solar panel will charge anything you use. For instance, a 100-watt solar panel will charge a 50-watt-hour smartwatch in half an hour. This simple formula is a must-know for all portable solar panels, especially if you have one without a built-in battery.

How To Make a Portable Solar Panel Charge Faster

To make a portable solar panel charge faster, follow these simple steps:

  1. Keep it under direct sunlight, ensuring the entire panel is exposed to UV rays. The good news is that portable solar panels can always be moved. You’ll likely have to move them every couple of hours if there are many trees, clouds, and other obstacles filtering the sunlight reaching the panels.
  2. Clean your portable solar panel before using it. Dust and debris can limit the sunshine a solar panel can absorb. Use a microfiber cloth to remove as much debris from the panels without scratching the surface. Never use abrasive materials (including steel wool, green sponges, etc.) because they can scratch the material.
  3. Disconnect all devices from the portable panel (aside from the optional external battery). Anything that depletes the battery will make the panel take much longer to charge completely. This includes smartphones, tablets, lights, smartwatches, and more. You can connect them once the panel charges the battery all the way.
  4. Choose a monocrystalline portable solar panel for cloudy days. They absorb more UV rays than polycrystalline panels. Clouds can drastically reduce the charging rate, so choosing the best panel cells is important. However, polycrystalline panels will work in a pinch (make sure they’re pointed at the sun, even if it’s behind the clouds).
  5. Dry the portable solar panel to remove all moisture. While many modern portable solar panels are moisture-resistant, water droplets can instantly limit how much sunlight the solar cells absorb. Again, microfiber cloths are the best choice because they don’t spread the liquid or leave lint behind.

Portable solar panels can only charge as fast as the maximum wattage allows. That said, many portable solar panels can’t work 100% efficiently. Cleaning, proper placement, and many other suggestions will drastically improve your portable solar panels’ ability to absorb sunlight and charge quickly.

Why Is Your Portable Solar Panel Charging Slowly?

Your portable solar panel is charging slowly because there’s not enough sunlight, it’s scratched, or the battery terminals aren’t connected properly. It could also be caused by reduced watt generation or a worn battery. The cables, panels, and batteries are all essential parts of the process.

Let’s review each of these details and factors below.

  • A lack of sunlight will reduce how quickly your portable panels charge. If it’s overcast, you can charge the batteries a little bit. However, portable solar panels can’t charge at all during the night. The best time is when there’s maximum UV production, which typically happens between 10 AM to 4 PM.
  • If the panels are scratched, they won’t be able to absorb or produce as much energy. Sadly, there’s not much you can do about scratched panels. The scratches are irreparable and usually spread until the panels no longer work. Never scrub a solar panel when dirt and other abrasive particles are on the surface.
  • Disconnected or loose battery terminals affect how quickly and efficiently a portable solar panel can charge anything. While the panel can pull a lot of sunlight, it needs to be able to produce the voltage and put it into the battery. Tighten the terminals and ensure there aren’t any exposed or damaged wires.
  • Low-wattage portable solar panels take much longer to charge, especially if the battery is too big for the panels. Many manufacturers produce low-wattage or low-voltage portable panels to cut corners. If the battery is too big for the panel, it won’t be able to charge quickly enough.
  • If the battery is old or overcharged too often (especially in deep-cycle batteries), it’ll take much longer to fill up by using the portable solar panels. Deep-cycle batteries shouldn’t be drained all the way. They retain a charging memory, which means they take longer to charge and don’t stay charged as long as they should.

The good news is that most of these issues are easy to fix. Unfortunately, you cannot do much to increase a low-wattage portable solar panel’s energy production (other than connecting it to another portable solar panel). Some portable solar panels don’t have built-in batteries, so they directly charge the connected device.

Does a Solar Panel’s Battery Size Affect the Charge Rate?

The battery a portable solar panel is connected to will affect how fast it charges because a bigger battery bank takes longer to charge. If you have a 100 amp hour battery, it’ll charge much quicker than a 150 amp hour battery. The same rules apply to built-in compact batteries in portable solar panels.

Another reason the battery matters is that the type of battery changes how long the battery lasts and how quickly it discharges. Li-ion batteries last significantly longer than deep-cycle batteries. While they’re much more expensive, they can greatly improve your portable solar panels. Some handheld panels have built-in li-ion batteries, making them excellent choices.

Final Thoughts

Portable solar panels usually charge within a day, but it depends on various factors. If you have a high-quality monocrystalline solar panel that’s 50 watts or more, it should quickly charge the battery. On the other hand, low-wattage solar panels typically take a lot longer to charge the battery.


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