Use A 10-Watt Solar Panel To Charge 12 Volt Batteries
Solar panels are everywhere now, and it’s easy to understand why. Being able to generate energy without using gas generators is pretty darn cool, and if you’re working on a project at home or want to charge a 12V battery without using regular AC outlets and battery chargers, a 10-watt solar panel can be the perfect solution.
If you have an RV or a trailer and don’t want to keep the power cord plugged in all the time to keep your batteries charged, a small 10W solar panel can be placed directly on your battery box and keep your batteries charged. For some, it’s all they’ll ever need even when they go camping since they only need enough battery power to run the water pump, a 12V TV, and lights in their camper. There are better solutions for if you need to run your furnace though, and I’ll talk more about that in the FAQ later on in the post.
A question that often comes up is: do I need a solar charge controller for a 10-watt solar panel? The answer is that it depends on how big the battery you’re going to charge is. The general rule is that you don’t need a solar charge controller if the solar panel puts out about 2 watts or less per 50 amp-hours of battery power.
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So if you’re planning on charging a 100Ah battery with a 10W panel, then you should use a solar charge controller. This applies to batteries under 100Ah as well.
You could connect a 10W panel directly to a 12V water pump or fan, but then it would shut off as soon as it wasn’t getting enough power. Therefore, it’s more functional to have the solar panel connected to a 12V battery.
Now, let’s compare and review the best 10-watt solar panels available. If you have any questions please leave a comment.
10 Watt Solar Panels Overview and Review
Newpowa makes solar panels in a lot of different sizes, so the fact that there is a 10 watt one is no surprise.
It’s rated at 0.58A max current, so it’s a good quality 10W panel. A 21.6V VOC rating is also pretty standard for a 12V panel.
Newpowa ships their 10W panel without any connectors, but bare wires, which is great if you’re going to use it to charge a 12V battery, but also if you plan on wiring it straight to a 12V accessory.
Bare wires also make it easy to install whatever connectors you would like.
Since the amperage of a 10W is relatively low, any 5A PWM/MPPT solar charge controller will do a good job. For reliability, I recommend a high-quality PWM charge controller like the Renogy Wanderer 10A.
A 4-stage charger like the Renogy Wanderer will take good care of your batteries, compared to some of the smaller 5A solar charge controllers available on the market that have one stage, and can damage the battery over time.
A 10W solar panel produces about 3 amps on a good day. If your 12V device uses more than 3 amps in a day, I would recommend going larger than a 10W panel.
So what does the Newpowa do good or bad compared to the rest? Well, it’s one of the lighter options, it has four mounting holes along the long side, it has bare wires which can be seen as both a pro and a con depending on how you plan to use it, and it has a 25-year transferable power output warranty from Newpowa.
The downside is that it’s a polycrystalline panel, so it is a larger panel to produce the same amount of power as a smaller monocrystalline panel.
Connecting it to a 12V battery
The bare wires on the Newpowa 10W make it easy to directly connect it to a solar charge controller. Make sure you connect the positive to the +, and the negative to the – on the charge controller.
Now you just have to make the connection between the charge controller and your batteries. A cable like the Renogy MC4 to alligator clips would work, you just have to cut off the MC4 connectors and plug the bare wires into the charge controller. I would also put a smaller fuse in the fuse holder.
Instead of cutting the MC4 connectors off, you could just get some Renogy MC4 to bare wire to connect to the charge controller. Then you would have
Remember that for the longevity of the 12V battery you should never let it go under 50% state of charge, and absolutely not under 30%.
The lightest panel on the list today is made by ECO-WORTHY. A somewhat unknown brand, but a growing one in solar power. Their 10W panel is a popular solar panel that is as basic as it can be. It doesn’t even come with any wiring.
I actually like this, since it lets you decide right from the start what connectors you want. If you are connecting it to a battery smaller than 100Ah, you would just get some 16 gauge electrical wire and connect it to the solar charge controller.
I will keep recommending the Renogy Wanderer 10A charge controller instead of smaller 5/7A charge controllers that aren’t reliable or smart multi-stage chargers.
Eco-worthy has put four holes on the back, and two on the sides for mounting it several ways. The junction box is waterproof.
It produces about 3 amps on a clear sunny day, so if the load will be greater than 3 amps, I recommend a larger panel. Eco-worthy has several choices, but its 12V 25 watt solar panel is another reliable choice that would be more fitting for RVers that need a small panel to keep their batteries charged to run the camper water pump and lights.
Unfortunately, this is another polycrystalline solar panel, so it will use more space to produce as much power as a 10W monocrystalline panel, but it’s somehow the lightest panel I am reviewing today.
This square panel from Acopower is a monocrystalline panel. It’s a 12V 10W solar panel, that comes with bare wires sticking out of its junction box.
You can expect this panel to produce about 3 amps on a sunny day.
Since it’s the first monocrystalline solar panel I am reviewing today, I should tell you what benefits it has over the polycrystalline panel.
Monocrystalline takes up less space to generate the same amount of amps as a polycrystalline panel, this results in a smaller panel size-wise to do the same thing. It also lasts longer than polycrystalline panels.
The bare wires can be wired directly to a large battery, but I recommend wiring it through a solar charge controller.
Note that it’s the only square-style panel on the list, which might matter to some depending on how they plan on using it. It has mounting holes on two of the four sides.
The Acopower 10W solar panel is one of the best panels on the list due to being monocrystalline. All of the panels on the list produce the same amount of amps, so it’s up to you if the space-saving and longevity benefits of a monocrystalline panel are worth it.
If I would be handing out designer awards today, Renogy would win the first prize. This slick, dark 10-watt panel is not a square but has a rectangular form.
It comes pre-wired with MC4 connectors, which means that it can’t be connected directly to a solar charge controller unless you cut the MC4 connectors off, or purchase some Renogy MC4 to bare wire connectors.
The benefit of setting up an MC4 connection between your panel and charge controller is that you get a quick disconnect.
Four pre-drilled holes on the back of the panel make it easy to mount the Renogy solar panel however you would like.
Renogy also sells a small tilt mount that might be useful to you. Tilting the panel towards the sun makes it more efficient, but I would expect this panel to produce about 3 amps per day even without tilting it.
The Renogy 10W is another top choice due to the high-efficiency monocrystalline cells used. I also like the form factor and design. Renogy makes high-quality panels that last, and I know that because I own several of them.
It’s one of the heavier panels on the list, but I wouldn’t ever let that stop me from buying a Renogy panel.
If you’re looking for a plug-and-play solar kit, Solperk has you covered.
This is a 10W solar panel with an 8A solar charge controller included. It also comes with the battery clamps to connect it to any 12V battery.
You can use this as both a charger and a maintenance device, as the solar charge controller is a three-stage charger with short circuit protection, open-circuit protection, reverse protection, overload protection, under-voltage protection, and overcharge protection.
Take it out, connect it to your RV 12V batteries, and let the sun do the rest. Note that a 10W panel only generates about 3 amps per day, and RV batteries are usually larger than 50Ah. So depending on use, you might need a larger one.
It is a polycrystalline panel, so it’s not the smallest or lightest panel on the list, but still, a good choice if you want the plug-and-play kind of system. The several SAE connectors that come pre-installed on the wires not only lets you easily connect and disconnect the different parts but make it easy to upgrade the kit even further in the future as you see fit.
The SAE connection between the solar panel and the charge controller means that you could also buy an extension cable if you’d want, without having to install any additional connectors.
Frequently Asked Questions
How do I connect a solar panel to a charge controller and a battery?
First, you would connect the wires from the solar panel to the solar charge controller. The easiest way to do this depends on what wires (if any) are coming out of your solar panel.
If the wires coming out of the solar panels are not long enough you can connect some MC4 connectors to the solar panel wires (or add some extra wire in between with some wire nuts), and some Renogy MC4 to bare wire cables on the charge controller side.
Make sure you’re connecting positive to positive, and negative to negative.
For MC4 connectors, I have a IWISS MC4 connector kit which includes everything you need to install MC4 connectors to wiring.
As seen in the photo of the Wanderer charge controller above, the first icon (from the left) is where you connect the solar panel, the second icon is the battery, and the third is a 12V load.
Do I need a solar charge controller?
If you’re charging a 12V battery with solar panels, a solar charge controller is often recommended.
A solar charge controller protects the batteries from overcharging by regulating the voltage and current produced by the solar panel.
But do you always need one?
Solar-electric has a good article about the basics of a solar charge controller that also talks about when a solar charge controller is necessary or not.
They write that an easy way to know whether you need one or not is whether the solar panel is more than 2 watt per 50Ah of battery. So if you have a 5-watt panel if your battery is under 150Ah, you need a solar charge controller.
I recommend using solar charge controllers with the 10-watt panels we’ve looked at today, but if we would use the rule it would only be necessary if your battery is smaller than 250Ah.
Which is the best? Monocrystalline Vs Polycrystalline?
Monocrystalline solar panels have several benefits over a polycrystalline panel.
They’re more space-efficient, have some of the highest efficiency rates, and last longer than polycrystalline panels. With a 15-20% efficiency rate versus 13-16%, monocrystalline panels take up less space to generate the same amount of electricity.
Monocrystalline panels are also more efficient in warm weather compared to polycrystalline which can suffer more from heat.
The downside with monocrystalline panels is that they create more waste to manufacture compared to polycrystalline panels. But since monocrystalline panels last longer, the question is which one creates the most waste over time?
What is the difference between a battery charger and a trickle charger?
A trickle charger is constantly charging the battery even if the battery is full. A battery charger is smarter and senses the battery voltage so it can stop charging when it’s full and only start charging again when the voltage has dropped below a certain level. This protects the battery from overcharging and longterm damage.
Which trickle charger is best for RV camper/trailer batteries?
There are a lot of solar trickle chargers out there, and I recommend the ones from reputable brands. A trickle charger like the Suner Power 8W is a great choice with all the accessories you get with it.
You’ll be able to not only charge your RV or trailer batteries, but also car batteries, test the panel to make sure it’s working, and smaller 12V batteries with the alligator clamps.
Can I use the same solar panels/trickle chargers on 6V or 24V batteries?
The panels we’ve looked at today are 12V panels that should only be connected to 12V batteries. You could use two 6 volt batteries wired in series which combines them and changes the voltage to 12V, but not just one since that would still be at 6 volts.