What Size Charge Controller Do I Need For 200 Watt Solar Panels?

Solar energy is a growing trend in today’s world where green technology decreases our carbon footprint and energy expenses. If you own a solar panel, you need a solar charge controller to help you regulate the battery charging process. So, what charge controller size do you need if you have 200 Watt solar panels?

The size of the charge controller depends on the wattage of your solar panels. It also depends on how many solar panels you have and the voltage of the battery. If you had two 200-watt solar panels and a 20V battery, you would see 20 Amps for your current. This is found by dividing the total Wattage (400) by the Voltage (20). That means that you would need a 20A charge controller.

Determining the size of the charge controller needed for your solar panels needs a bit of simple math. Luckily, math won’t be too difficult. Using the right solar charge controller is important because you can potentially lose up to half of the power generated by your solar panels if you are using an improper controller. That’s why you have to read on to find out more about solar panels and solar charge controllers.

What Are Solar Charge Controllers?

When using solar panels, you need something to regulate the power generated so the batteries storing the power from the panels do not get overcharged. This is where solar charge controllers come in to help regulate the battery charging process.

Solar charge controllers also called solar regulators because the flow of energy from the solar panel to the battery is regulated by them so that the batteries or the storage used for the energy coming from the solar panels are charged correctly. 

The charge is basically limited so the batteries don’t overcharge, which spells disaster for your batteries. Solar charge controllers are also useful in preventing drainage because they shut the batteries down whenever they fall below a certain level. In short, solar charge controllers keep the batteries healthy and ensure their life is lengthened and preserved.

Think of it in a way where the solar charge controllers act as the faucet that controls the amount of water that passes through the pipes so that water doesn’t flood your sink. They essentially regulate the flow of electricity coming from the solar panels so that your batteries won’t end up with more energy than they can handle. This allows you to preserve the battery life as well as energy generated by your solar panels. 

How Do Solar Charge Controllers Work?

So, how do solar charge controllers work? Let us revisit the faucet or valve metaphor where the water coming from the pipes is the electricity generated by your solar panels and your sink is the battery. In such a situation, your valve or faucet is what regulates the water coming through the pipes. Hence, that is the solar charge controller in this situation.

The solar charge controller acts like a valve that regulates electricity coming from the semiconductor before electricity reaches the batteries. So, what happens here is that the solar charge controller controls the energy output from the solar panels and only allows the right amount of electricity to pass through to the batteries to make sure that you don’t overcharge them or to see to it that the batteries only get the energy they can contain.

The batteries are then used to power the electrical components of your house or RV as the solar charge controller continues to feed the batteries the electricity they need to fill up once again. So, in this case, you would need a solar charge controller that is actually compatible with the battery you are using while also capable of handling the load coming from the solar panels.

How To Choose The Right Charge Controller For 200 Watt Solar Panels?

Now you know about solar charge controllers. It is important to know that solar charge controllers don’t come in the same capacities. The solar charge controller required for your solar panels depends on the wattage of the solar panels themselves and on the voltage of the batteries in use.

So what size charge controller do you need for 200 watt solar panels?

The solar charge controller Amp (A) rating must be between 10 to 20 percent of your battery’s Amp per hour. So, in this case, if we were to use a battery with an Ah of 200, the solar charge controller should be between 20 to 40A. This also means that we need a solar panel that is able to generate a current that is at least 20A so that the battery would be able to reach the right voltage.

Calculating The Amps Of The Charge Controller For 200 Watt Solar Panels

However, it would be simpler to determine the solar charge controller needed. We may have to use simple math in this case. A simple formula for the power or wattage of your solar panels should look like this:

Wattage = Voltage x Amp

So, since we are not looking for the Wattage or the power of the solar panels here because we already have a given value of 200 Watts for our solar panels, let us re-arrange the formula so that we would end up looking for the current (A) of the solar charge controller instead. So, the formula would now look like this:

Amp = Wattage/Voltage

The solar charge controller needed for a 200-Watt solar panel now depends on the voltage of the battery that you would be using. If you use a 12V battery in this case, then that would be 200/12 which is roughly equal to 16.7. As such, the solar charge controller needed should be capable of handling 16.7A. In this case, a 20A solar charge controller should be enough.

However, note that you would be needing a bigger solar charge controller if you were to use more solar panels. So, if you used two 200-watt solar panels and a 12V battery, the solar charge controller would easily handle 33A. Hence, it is best to use a solar charge controller that is 35A or bigger.

Best Solar Charge Controller For 200 Watt Solar Panels?

If you need a solar charge controller that works well with your 200-watt solar panel, you might be interested in:

GHB 20A Intelligent Charge Controller

The GHB 20A Intelligent Charge Controller is good and cheap. It has the functionality that allows it to work with smaller solar panels. Equipped with some of the neat basic features that are actually enough for you to properly monitor your battery’s health. With an interface that can be useful when it comes to understanding what is happening to your solar panels and batteries. If you need the GHB 20A Intelligent Charge Controller.

Renogy Rover 20Amp

The Renogy Rover 20Amp is great because it automatically detects the voltage of the DC systems and the batteries and adjusts accordingly. It also comes with electronic protection that ensures you don’t end up overcharging or discharging your batteries. It comes with gel sealant to make sure it lasts a long time. This charge controller is one of the most used 20A charge controllers on the market.

Renogy Adventurer

Meant for two 200-Watt solar panels. The Adventurer is more expensive than other solar charge controllers because it’s bigger but works perfectly. That means that it works efficiently because of how its cooling system allows it to function without getting too hot. And while it might be huge, its aluminum build allows it to stay lightweight. This 20A solar charge controller is the most sought after unit for RV flexible solar panels and portable installations.

Further Reading

For more information on how to size your Renogy charge controller to the right solar panels, check out Renogy’s quick guide.

If you haven’t found your solar panels yet, be sure to check out our best camping solar panels guide. Camping may not be your intended use. In that case, try reading our detailed reviews of the best portable solar panels.


I'm trying to make the world a bit greener every day, whether that's through my day job or helping others make green choices for their homes.

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