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Two Charge Controllers One Solar Panel

By Benjamin Strusnik July 15, 2022

two charge controllers one solar panel

A charge controller is used to regulate the power of your solar modules. It ensures that your battery does not overcharge. 

While most systems work perfectly using just one charge controller, there are some instances where connecting two charge controllers to one solar panel could be the right solution. 

Check out our article to find out what a solar charge controller is, how it works, and whether you can use multiple chargers on a single solar panel.

What Is a Solar Charge Controller?

A solar charge controller controls the power going into the battery bank from the solar array. It makes sure that the deep cycle batteries do not overcharge during the day. 

two charge controllers and one solar panel

It also ensures that the power doesn’t run back to the solar panels overnight, draining the batteries. 

Some charge controllers come with extra capabilities. These include lighting and load control. Managing the power, however, is its main job.

A solar charge controller comes in two different technologies. These are PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). 

Difference Between a PWM and MPPT Charge Controller

PWM type charge controllers are less complex than MPPT type charge controllers. 

MPPT-type charge controllers convert excess panel voltage into higher charging amps. This means that they can produce approximately 15% more power than PWM-type charge controllers.

The way each system functions is different. An MPPT charge controller costs more than a PWM charge controller. However, it’s often a better decision to pay the extra money for the MPPT.

PWM Solar Charge Controller

PWM controllers work by making a connection directly from the solar array to the battery bank. When you bulk charge, there’s a continuous connection from the array to the battery bank. 

The array output voltage is reduced to the battery’s voltage. As the battery charges, the internal voltage rises. The voltage output of the solar panel rises as well. This uses more solar power while charging. 

You need to ensure the nominal voltage of the solar array matches the voltage of the battery bank. 

MPPT Solar Charge Controller

The PV voltage is reduced to match the battery voltage after measuring the Vmp voltage of the panel. 

two charge controllers with one solar panel

When the voltage is reduced to match the battery bank, the current increases. This utilizes more of the panel's available power. This is because power into the charge controller equals power out of the charge controller (V=IR). 

Instead of batteries, you can utilize a higher voltage solar array, such as the more widely accessible solar panels. 

Important Terms to Understand

When solar charging two battery banks, the following terms are crucial to understanding:

Solar charge controller: Prevents your battery or batteries from being overcharged by the solar panel.

Dual Battery Bank: Having two separate batteries or sets of batteries that are capable of carrying out various tasks. Start batteries and the house battery bank in an RV are two examples of this.

Solar array: A solar array is a panel or group of panels that use the sun's energy to charge batteries.

Can I Use Multiple Charge Controllers?

With most solar charge controllers, you can only charge one battery. So, you need to know how to charge multiple batteries with one solar panel.

Some charge controllers now have an added option of having two battery banks. You charge the two banks separately using the same solar panels and the same controller.

You should also find out what batteries to use for your solar panels.

You can use multiple charge controllers if the charging current of your solar array is more than the current of your charge controller. 

Throughout the battery bank, these charge controllers are connected to one another in parallel.

A single battery bank can power two or more controllers. Large solar arrays are typically configured in this way to provide the optimum benefits. However, there are a few considerations you should make before purchasing additional controllers.

one solar panel two charge controllers

Capacity

The capacity of a charge controller is one consideration. The other is the maximum number of watts that MPPT and PWM controllers can handle.

It’s difficult to mix different wattage solar panels, but not impossible.

A separate solar panel is required for each controller. There must be no other connection between the two solar panels except for the battery bank. The battery bank will be connected to each controller. 

In this setup, each charge controller assesses the battery voltage and chooses the amount of current that is sent to its own solar panel.

It's quite common to use two or more controllers with a single battery bank. It’s particularly useful in big arrays because of how MPPT controllers operate.

It may be better to install multiple charge controllers instead of one large one. 

This is because different controllers may have a higher system output if some panels are in the shade and others receive direct sunlight.

When Is It Essential to Have Multiple Charge Controllers

Complete reliance on an off-grid power system can be extremely important if you rely on them for crucial equipment. You may have vital control or life support systems that depend on constant power availability. In this case, your power generation needs to have some redundancy.

Critical systems like navigation and weather warnings can’t afford to lose power while a sailboat is sailing the Pacific. Installing solar panels on a boat is important. The designed redundancy in such power systems can save lives. 

In off-grid areas, it’s common for weather conditions to quickly change. It’s crucial for solar, wind, hydro, and other renewable power sources to be able to generate electricity in these areas. 

It’s important to know how to set up solar panels off-grid.

one solar panel and two charge controllers

Is It Dangerous?

It’s possible to have two charge controllers on one solar panel, however, it may not be the best option.

Once the battery is full, the charge controller switch will be mostly off. The other charge controller will then use the solar cell.

The danger might be that if both batteries are low, both controllers will switch on together. This could shorten two batteries together which will damage the controllers. 

Benefits of Solar Battery Charging

1. Solar Power Prolongs Battery Life

Your batteries need pure D.C electricity. Solar panels can produce this when they are exposed to sunlight. 

Charging your batteries through solar power helps to prevent ongoing deep discharges. These discharges shorten the lifespan of lead-acid batteries.

Solar power prevents this as the batteries are saturated with electrons daily. With solar charging, you can easily double the life of your lead-acid batteries. 

one solar panel with two charge controllers

2. Quiet, Clean, & Easy to Use

-Solar panels release no waste and use no fuel.

-There is no mechanical noise because there are no moving parts.

3. Low Maintenance

There are no air, fuel, or oil filters to change since solar panels consume no fuel and have no moving parts to wear out. All you need to do is keep the panel surfaces clean.

4. It's Safe and Reliable

There’s a little chance of starting electrical fires or being electrocuted. A system must be installed using proper wire sizes and fuses. If it’s done properly, then it’ll be safe.

5. Electrical Independence

You can stay wherever you want if you have the right sized system and the relevant components. There will be no need to use a generator or seek alternative power. 

You will be free to go wherever your heart desires, knowing that you have electrical independence.

Can I Use MPPT and PWM Charge Controllers Together?

one solar panel & two charge controllers

PWM controllers are best suited for small systems, while MPPT controllers are for large solar arrays. But can you use the two together in one system?

We do not recommend using different types of charge controllers together in one system. These controllers have unique properties. Using them together can result in a system's malfunction. You will also not get optimal results from your batteries and solar panel.

An MPPT controller is more efficient than a PWM. An MPPT can handle solar panels and batteries with different voltages. The battery voltages and panels have to match with a PWM. If you have an MPPT and PWM controller in one system, the voltages would need to be adjusted differently to one another.

If you have two solar arrays wired together, you can’t use different controller types unless the arrays are linked. It would still be considered a single system. Conflict may arise if you use different types of charge controllers.

You can use different size controllers, but they have to be the same type. For example, if you are going to use PWM then you need to use PWM only, and vice versa.

What Should I Look for When Buying a Solar Panel?

There are many different solar panels available to purchase. Knowing which one to buy can be tricky.

You first want to look for one that’s low maintenance. This saves you money in the long run.

You should also look for a solar panel that can withstand harsh environmental conditions. Good low light performance in cloudy conditions is also advantageous. 

In terms of installation, it should be easy to install and compatible with on-grid and off-grid inverters. Pre-drilled holes are also a bonus.

single solar panel two charge controllers

Always try to buy one with a warranty. This will ensure that you don’t lose out on money if something breaks.

Shop Solar Kits has the perfect 200 Watt Portable Solar panel that meets most of these specifications. It also comes at an affordable price.

Key Takeaways

Using solar power for battery charging is a reliable, low-maintenance way to prolong the life of your battery.

In certain circumstances, you will be able to use two charge controllers with one solar panel. There are a few considerations your should make before doing this.

The charging current of your planned solar panel might be more than the current rating of your charge controller. In this case, you should use multiple charge controllers.

A single battery bank can power two or more controllers. However, a separate solar panel is usually needed for each controller. 

Luckily these days you get charge controllers that can charge two battery banks with one solar panel.

If you live in an off-grid area then generating electricity through solar power is one of the best options.

Remember when purchasing a solar panel to look for one that is low-maintenance, can withstand harsh environmental conditions, and is easy to install.

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