Solar battery charger guide

All-Encompassing Guide to Solar Battery Chargers

Solar battery chargers allow you to have a reliable source of power at home or on the road. Solar energy can charge your phone while you're out camping, power a car, RV, or electric scooter, or even become your home's primary everyday power source. A large solar kit can save you thousands on monthly utility bills and get you off the grid - all while living a greener lifestyle.

Solar energy is currently the most common source of off-the-grid power, and solar is one of the fastest-growing energy sources. If you have access to a decent amount of sunlight and a good quality solar battery charger, then you can rest easy about keeping your electronics charged and ready for use. Read on to learn how solar battery chargers work and how you can use them. 

How do solar batteries work?

A solar battery is a form of power storage. Not all solar-powered energy systems require batteries, but they're an excellent addition for anyone who needs to store backup energy for bad weather or emergencies.

Solar chargers work by taking energy absorbed through solar panels and using it to charge solar batteries. Multiple solar cells make up the solar panels and work to absorb sunlight and convert it into electricity. The solar batteries then store the energy produced by your solar panels for later use.

There are many types of solar batteries; some are small and portable, others can be utility-scale. The higher your battery's capacity, the more solar energy you can store.

Solar power requires direct sunshine to hit the surface of a solar panel to produce the maximum-rated power. Overcast weather or short winter days will reduce your solar panel output and result in slow battery charging. The larger the solar panel’s surface, the more sunlight it can collect and the faster it can convert power to be stored in a battery.

You can use a small handheld solar battery as a portable energy source. Small, lightweight batteries make great backup energy sources for outdoor camping adventures or events. A small electronic device like a phone or camera can easily be connected to a solar battery and recharged.

On the upper end of the scale, you can use solar to power your entire home. If you need a significant amount of solar energy for an RV, cabin, or house, you will need good weather conditions and some patience to charge batteries fully. Larger solar systems for vehicles are often portable solar panels paired with solar battery storage to provide lasting power on the go.

Installing larger solar panels and batteries as part of your home's solar panel system allows you to store any excess solar electricity - instead of sending it back into the grid. Having a backup solar battery bank can also be helpful in case of an emergency power outage. 

How do solar battery chargers work?

A solar battery works with a solar energy producer and charger; the solar charger supplies solar electricity to devices or batteries. Solar battery chargers are generally portable, but you can also install them in stationary locations such as rooftops or ground. These stationary solar chargers can be connected to a battery or battery bank and store energy for off-peak usage.

How exactly do solar chargers work? First, you need to expose the device to a decent amount of sunlight so it can charge. Solar chargers won't work well at night or on overcast days. On a sunny day, the sunlight strikes the surface of your solar charging device and gets absorbed by the individual solar cells.

Photons particles from the sunlight then excite the electrons within the solar device to create an electric field. This electric field produces a force by which the electrons can travel to your solar battery charger.

Many chargers cannot directly push electricity into your devices. Therefore an onboard extended-life battery pack is often included within the device. The battery can be charged by the solar panel when not charging anything else. This system allows the battery to store electricity for use at another time or overnight.

Your solar battery will store your solar electricity until you are ready to charge your compatible devices. Not all devices use DC electricity to charge their batteries, so you may also need to use a charge inverter, which switches the electricity from direct current (DC) to alternating current (AC). This process converts the electricity into a more usable form for devices that use DC electricity. Note that not all devices will require a charge inverter.

You can use solar charger power to directly charge up various handheld devices, such as phones and small electronics, using nothing more than the energy from the sun. Many of these small portable all-in-one solar chargers and batteries have USB connections, so you can charge your smartphone, tablet, or any other device that's capable of charging via USB.

The solar panels used in consumer solar battery chargers are not as powerful as those used in residential or commercial solar power systems. The solar energy technology is the same, but the panels used in smaller solar battery chargers are far more limited in the power levels they can put out.

It can be time-consuming to charge a large battery if you are relying entirely on solar power. Solar trickle chargers are popular because they help maintain a battery’s life instead of trying to charge a dead battery from scratch. All batteries naturally self-discharge to some extent, but solar power from a trickle charger can be used to replace the self-discharge of a battery that’s not in use. With solar energy, you can keep your battery charged so it will never go dead.

Do solar battery chargers really work?

There are now many solar battery chargers available on the market, and like any product, they vary in price and quality. If you're new to solar energy, it's common to be suspicious of cheap solar batteries or have unrealistic expectations. But, when used as intended, high-quality solar batteries and chargers really do work.

Unlike standard battery chargers, solar chargers work anywhere with a clear view of the sky and sunlight. If you're accustomed to using power outlets, this concept can be quite a change. It's common to feel skeptical at first about whether a solar charger can deliver enough juice to power your vehicle, home, or devices.

Rest assured that solar battery chargers do work, but they also have limitations that new users should understand before using them. Solar power relies on sunlight to charge, so solar energy can't be generated 24/7. You shouldn't expect to fully charge a solar battery as quickly or at the same rate as you would with electricity from a power outlet.

Solar battery charger uses

Solar battery chargers are becoming more common and widespread. Different-sized chargers and batteries can serve different purposes; popular uses of solar chargers include cars, RVs, boats, and phones.

Cars & RVs

Solar power is a great energy source for cars, RVs, and trailers. Solar battery chargers give you the flexibility and freedom to store solar power, so you can take your van life anywhere and maintain power even when sunshine is not readily available.

Charging your vehicle’s battery with a solar trickle charger is a convenient option to maintain your battery. Just connect the device and leave your solar panel on the vehicle's dashboard

Renogy's RV solar kits can power a variety of outdoor vehicles. Our DIY packages are a perfect turn-key solar solution. Each of our kits comes equipped with the necessary components for easy installation. Our packages range from beginner through intermediate and up to advanced so that you can find the perfect equipment for your power needs. 

Marine Transportation, Yachts & Boats

Solar power allows marine enthusiasts to have more time out on the water, enjoying themselves with less worry about energy reserves.

Renogy offers solar kits suitable for a wide range of marine transportation, including speedboats, motorboats, houseboats, and pontoons. Our preselected maritime power kits range from 100W to 350W, are designed with marine spatial requirements in mind, and are a space-efficient battery maintaining solution. 


Portable phone chargers are one the most common types of solar chargers available on the market. In a world where we are now reliant on our phones, keeping them charged in any circumstance is one of modern life's top priorities.

Small portable solar charger models can charge a range of different cell phones, iPods, headphones, smartwatches, or other portable audio equipment.

How to choose the best solar battery charger for a solar energy system

The best solar battery charger for your system depends on your needs. Some smaller, cheaper chargers are suitable for only one specific use, such as charging a phone. Others are more versatile and use adapters to charge anything from a boat battery to an RV.

Standard chargers use multiple amperage settings so that they can charge electronics quickly. But small portable solar battery chargers often put out just a small amount of current. For example, a 100 AH battery will only provide you around 40 minutes of usage at 100 amps.

To figure out your solar power needs, you need first to understand the output of all your available energy sources. Secondly, you need to figure out how much energy you actually need to use per day.

For this reason, solar battery chargers are often better and more practical at maintaining a charge than reviving a device that has a completely dead battery. Batteries naturally lose power over time and can go flat. A charger like the 10W Solar Battery Trickle Charger Maintainer will help you maintain a healthy battery.

In some cases, it's best to use solar power to charge up a battery, then use the battery to charge your device, rather than try to charge an electronic device directly. The Renogy Solar Calculator will help you do the math and determine which solar battery charger and process is best for your specific requirements. 

Portable solar battery chargers

Portable solar chargers allow you to travel freely and with more flexibility. You don't need to be tied to wall outlets or power bills when you have a reliable way to charge a device in the great outdoors. You can mount a portable device on your backpack or outside your vehicle, so it will charge while you go about your day. Many outdoor activities like sea kayaking or mountain touring are particularly well suited to the "on-the-go" nature of portable solar charging.

Portable solar battery chargers need to travel well, so they are often manufactured using thin-film PV, so they are rollable or flexible. Rollable solar chargers often include Li-ion batteries within their designs.

Even a small portable charger with a small solar panel can charge your phone or camera on the go, so you can use them almost anywhere. A charger like the E.POWER 20000MAH portable solar charger is the size of a cell phone and compact enough to fit in your pocket or easily attach to your backpack. A more robust solar battery charger can power your RV, cabin, or car with solar power as well. 

Key specs for portable battery packs

If you’re new to solar power, the amount of information may seem daunting. These are the key specs to consider when choosing portable battery packs.

Storage Capacity

When choosing a portable battery pack, you need to know how much energy you can store relative to what you need to charge. Storage capacity measures how much charge the battery pack can keep to recharge your devices before it, in turn, needs recharging.

Check your device’s storage capacity and compare it to the battery’s storage capacity; this will tell you roughly how many times you can recharge your device. For electronics, you can check the technical specs to find the battery specifications and capacity. You may need to convert the power units between the device and your battery pack for this research.

Power Output

The charger’s output is measured in volts and must be equal to your electronic device’s input battery voltage requirement. If the charger output is lower, then you can actually drain your device’s battery instead of charging it.

Small electronic devices, such as phones and MP3 players, which can be charged with a USB cable, need a 5V output rating. But larger electronic devices such as laptops require a DC power input. These larger devices may need a larger portable battery pack with a 12V – 24V output rating.

Battery technology

Portable battery packs vary in technology, size, and weight. The most common battery types are Nickel-metal hydride batteries, lithium-iron or lithium polymers, and lead-acid batteries.

The most common types of solar batteries

There are many types of solar batteries on the market. To choose the best solar battery for your needs, you need to consider what you want to power, how much power you need, and how much space you have to store your battery or battery bank.

The most common types of solar batteries are either lead-acid batteries or lithium iron phosphate batteries. As their names suggest, lead-acid batteries use lead, while lithium-iron batteries use metal lithium. Both battery options can be effective energy storage solutions, but they each have differences in performance and cost.

Flooded Lead-Acid (FLA)

Flooded lead-acid (FLA) batteries have a long and solid track record in solar power use. Lead-acid batteries store electrical energy by using chemical reactions between lead, water, and sulfuric acid. This older technology is robust and reliable, making lead-acid batteries affordable to make and use. They are still the most common solar battery for use in stand-alone alternative energy systems.

FLA batteries have the most extended energy life and one of the lowest costs per amp-hour of any battery option. These batteries emit hydrogen gas as a by-product, so they must be well ventilated, and they do require regular maintenance. You will need to open the battery and add distilled water regularly, usually every one to three months.

When correctly maintained, FLA batteries can last between 5 to 8 years in a home energy setup. But if you don't maintain them, then the lifespan of the battery will be significantly decreased.

To provide power to an entire home or large vehicle, you usually need a bank of FLA batteries, and storing a bank of deep-cycle FLA batteries can be difficult in small spaces. These batteries are large, heavy, and need to be stored upright. These are good, low-cost battery options for users who have more space available and want to be hands-on in managing their solar system.

Sealed Lead-Acid (SLA)

You can find sealed lead-acid (SLA) batteries in everything from toys and vehicles to daily appliances. These are also known as valve-regulated lead-acid (VRLA) batteries. They are a common battery choice to power many of the products we use every day and are an excellent way to store solar energy.

SLA batteries are sealed and don’t need to be refilled with water, making them a lower maintenance option compared to an FLA battery. However, you will need to vent SLA batteries to prevent hydrogen gas buildup. A valve controls this vent, hence the alternative name of valve-regulated lead-acid batteries.

SLA batteries can be left idle for long periods without discharging while you're away, making them a good choice for people who can't check their batteries regularly. The longevity of these batteries makes them a popular choice for seasonal cabins or other off-grid properties.

Unlike FLA batteries, sealed lead-acid batteries are spill-proof and non-hazardous. The SLA batteries can be stored on their sides or stacked for easy storage, making them a good solution for smaller spaces.

Lithium Iron Phosphate (LFP)

Lithium iron phosphate batteries are a premium battery option with high power density. These batteries are relatively small and light compared to lead-acid batteries. They are highly efficient and have fast charge and discharge rates.

This type of battery is well suited to extreme temperatures, and their smaller size makes them a good choice for vehicles or traveling. LFPs have lots of benefits compared to lead-acid batteries and other lithium batteries, but they are usually more expensive. Several benefits justify the higher prices, including a longer lifespan, no maintenance, no need for ventilation, and more efficient power usage.

Many lithium iron phosphate batteries come with warranties, and they won't need replacing as often as lead-acid options. If you want a battery with a long lifespan and little to no maintenance, this is a good choice.

Output connectors and adapters

Some solar panels come with an included battery which is either integrated or independent and attached. These models will include any necessary connectors between the panel and battery.

However, suppose you buy solar panels and batteries separately. In that case, you will need to check what output connector it has whether it is suitable to connect to and charge your device directly. Connectors attach different solar components together to produce a safe and successful flow of electricity.In some cases, your solar panels may need to be connected to a separate battery pack before charging a device.

Solar Chargers vs. External Batteries

You may be considering whether you need a solar charger or an external battery. For short trips, such as overnight camping, an external battery pack should be sufficient. A small external battery can be charged from a wall socket or using a USB plug and can power small devices like your cell phone for a day or two.

However, when the external battery runs out of power, it needs to be plugged in to recharge. On extended trips of more than a day or two, you're likely to run out of juice from an external battery while you're still out in the wilderness.

A portable solar charger can continue to produce power and recharge every day in the sun. For the best of both worlds, choose a portable solar charger that can also charge through a USB cable. This way, you can fully charge the battery at home before you set off, then top it up using the solar panels while outdoors. 

Ready to get started with solar power?

If you're new to solar power or looking to expand your system, our calculators can help you get started. If you aren't sure how much solar energy you need, our Renogy Solar Panel Calculator will help you estimate your power project. You can input information about your lifestyle, your devices, how long you plan on running your devices, and the average sun-hours available per day in your location. 

Our solar sizing calculator will then be able to calculate the minimum and recommended system size and the recommended battery output. Try out our calculators and start your solar journey today.