So you have your solar panel. But you found out that its voltage is greater than your battery. And that would cause problems. So can you reduce your solar panel voltage?
The easiest way you can reduce your Solar Panel’s Voltage is by using either an MPPT Charge Controller or a Step-Down Converter (aka Buck Converter). Other solutions are to use resistors or modify the solar cells’ connections via the junction box.
Before we embark on how you can reduce your solar panel’s voltage, we have to know how much voltage your average solar panel produces. Then how to properly test how much voltage your panel is producing. Then learn in-depth about each possible way to reduce the voltage.
Though you can effectively reduce solar panel voltage by following the article, in some cases the most cost-effective and time-saving solution is to buy a compatible solar panel. Anyway, let us dive in on how you can make your panel compatible.
Table of Contents
What Voltage Should Your Solar Panel Produce?
Just look at the back of your panel. They should be listing how many volts your panel should be producing. Another way is to estimate by counting solar cell count.
First of all solar panels are a collection of solar cells. When the light hit them, they collectively produce voltage. Voltage production depends on environmental factors and various things. Anyway on average your panel would produce slightly half of your panel’s cell count.
For example. You have your standard 32-Cell panel. It’ll be outputting 14V to 15V.
How to Check Your Solar Panel’s Voltage?
Before planning to reduce your solar panel you have to make sure your panel is performing well. If it is broken and producing low voltage you’ll have problems in the long run.
First, perform an Open Circuit Voltage Test.
- Step 1: Put your Solar Panel in a Sunny Place
- Step 2: Take Your Multimeter and Set it to DC
- Step 3: Disconnect your Panel from System;
- Step 4: Take the Negative Lead and connect to the Negative Terminal of the Multimeter;
- Step 5: And just like that take the positive lead and connect it to the Positive Terminal.
Read the voltage. Then compare it to the label at the back of the panel. If they are similar or very close to each other, your panel is performing correctly.
Why Should You Reduce Your Solar Panel Voltage?
Most experienced people know why sometimes you need to reduce your panel’s voltage. But in case you are inexperienced, it is an easy mistake to think that you can use a high voltage incompatible panel.
If you use an incompatible panel, especially a high voltage one, the additional produced current would be turned to heat. And it would cause overheating of your system and cause costly damage to your system.
So it’s important that you use compatible panels or reduce the voltage of Solar Panels via any means. For both safety and saving money.
How can you Reduce Solar Panel Voltage?
To my knowledge, there are four main ways you can reduce the voltage of your panel and make it compatible with your equipment. They are using MPPT Charge Controller, Step Down Converter, Using Resistors, and finally reconfiguring the cell connections via Junction Box.
Each of the methods how you can set them up is discussed below
Use MPPT Charge Controller to Reduce Solar Panel Voltage
MPPT Charge Controller is quite possibly the highest quality Solar Charge Controller you can buy. MPPT (Maximum Power Point Tracking) Charge Controller can easily match the voltage between panel and battery.
MPPT charge controllers are created to maximize the efficiency and amp solar panels provide. So they possess the mechanism to dynamically match voltage to ensure that you get the most amp.
The keyword here is matching voltage. If you have an incompatible voltage panel, the MPPT charge controller will automatically optimize it.
If money is not your issue, I’ll recommend MPPT Charge Controller the most. Not only will it match your voltage but all make your Solar Powered System very efficient.
Also setting it up is very easy. You can follow your manual or Follow the steps below to attach your charge controller to your system
- Step 1: At first connect your battery to the charge controller.
- Step 2: Connect Negative Battery Cable to Negative Terminal of Charge Controller. Same as that Positive Battery Cable to Positive Terminal of Charge Controller.
- Step 3: Connect Negative Battery Cable to Battery Terminal. After that connect the Positive Battery Cable.
- Step 4: Now find the MC4 cable connectors at the back of your panel. As expected connect the positive cable to the positive adapter cable and negative to negative. (Pro Tip: Make sure the exposed wires never touch each other)
- Step 5: Finally connect the panel with your charge controller.
Use Step Down Converter
Now on to Step Down Converter. The step-down converter works somewhat like your MPPT Charge Controller. In simple words, it lowers or steps down the voltage as the name suggests.
The thing about Step Down Converter is that it is cheaper than MPPT but probably not as reliable as the former.
Anyway, you set up your Step Down Converter similarly to your charge controller. There should be ports in the device for connecting the Battery and Solar Panel. It all boils down to not messing up the terminals.
After you set up your Step Down Converter, you should get a screwdriver and multimeter. Hook the multimeter up to measure voltage. Now you should be able to spot two circular button-like things. Use your screwdriver to adjust the voltage.
This method is way more hassle than the previous method. And this method also has various inconveniences you can face. This will be discussed in the next section in detail.
Use Resistors to Reduce Voltage
Remember those circuit equations back in Highschool Physics. Today we will be using their application to reduce the voltage of your panel. Seem fun, doesn’t it?
Firstly you will need two resistors. Now let’s say you have a 24V panel. We can half that and make it 12V using the resistors. Here is how?
Take two Resistors. Now Connect both of them in Series. Connect one end of the series system with the positive terminal of the Solar Panel. Now you can take reduced voltage as output from the middle point of the two resistors.
The more interesting thing is you can manipulate the value Resistance to optimize the amount of reduced voltage. Here is how the whole thing work.
R1 x V-(Reduced) = R2 x [V-(Panel) – V-(Reduced)]
Here R1 is the value of the first resistor, and R2 is the value of the second resistor. V-(Reduced) is the reduced voltage you want to get. V-(Panel) is the voltage of the panel. All you have to do here is to figure out the value of Resistors. For example, if you use two ten thousand ohm resistors you can half the voltage of the panel.
In my opinion, this method should be used if you are looking to experiment with circuits. This is no long-term reliable solution due to various factors.
Reconfiguring the Panel Via Junction Box
First of all, do not attempt this if you have minimal knowledge regarding electronics. Only attempt this if you want to do it for the sake of tinkering around.
Most solar panels are two parts wired in series for more voltage. See where it is going? Now if you can somehow manage to make the connection parallel you can reduce the voltage (Halve the voltage to be exact). You can do this exactly via the Junction.
Before you attempt this or do this, this method is not easy and can result in your solar panel getting damaged if you don’t know what exactly you are doing. Do this only if you are experimenting with your panel and want to learn more about its internal mechanisms, not for practical reasons.
What Method Works the Best?
So amongst these four what method is the best? In my opinion, you should either use an MPPT charge controller or consider buying a compatible panel if you want the least amount of hassle and issues.
Here is a detailed explanation.
First of all, let’s talk about the Step Down Converter. It is quite cheap which is great for saving money. But the main problem is when your voltage fluctuates. Weather can often cause it. It often time results in the loss of efficiency. That’s why you need precise calibration
The resistor method suffers from the same issue. Voltage fluctuation will cause problems in your apparatus since the Resistors aren’t variable. Plus there is the issue of wiring a complicated circuit. It’s better to buy MPPT Charge Controller or replace your panel instead.
The fourth method (Junction Box reconfiguration) is directly tinkering with your panel. One wrong step will result in your panel getting broken. Not only that but you may only be able to halve the voltage. Instead of messing around with it, buying an MPPT Charge Controller is way more practical and rational.
So in one statement, I’d recommend you to buy the MPPT Charge Controller. And in the case it is unavailable to you you can use the step-down converter.
Conclusion
Reducing the Voltage of a Solar Panel is very important if you are unable to find any compatible panels for your system. It’s essentially a safety measure. It can easily be done by connecting an MPPT Solar Charge Controller or Step Down Converter. Or if you are feeling adventurous you can go the experimental route.
All in all, I hope this article helped you to learn a thing or two and hopefully gave a you reliable method to resolve your issue.