Reduce Solar Panel Voltage (Volts + Calculations)

To reduce the voltage on a solar panel, there are a couple of ways to answer that question. If you ask about reducing the voltage from a solar panel as it functions, the answer is an easy fix.

If you ask how to draw down the voltage in a solar panel that is not working, the answer is different but also easy. 

There are situations where you would want to reduce the output (voltage) of a solar panel, such as reducing a 12-volt panel to work on a 6-volt battery.

 In this blog, we discuss:

  • The ways to reduce the voltage from a solar panel
  • How many volts a solar panel should produce
  • The calculations of volts to watts and how amps play into that
  • And a few more things that are important to know. 

There is also the situation where a panel needs maintenance or repair, and to do so safely, the panel must discharge much of the energy stored in it. Those are two different situations, and we will go through both.

How do solar panels reduce voltage?

The easiest and safest way to reduce the voltage from a solar panel that is operating is to connect it to a step-down converter. These are also known as Buck Converters. 

A buck converter reduces the output of the solar panel — the energy flowing out of the solar panel — to match the input requirements of the battery or device.

Solar panels produce energy in DC format. The converter is not inverting the power, simply reducing the number of volts reaching the battery. 

If you needed to reduce the solar panel’s power for maintenance, you would not use a converter.

Instead, you would attach the solar panel to a lead-acid battery and allow the battery to drain the power from the solar panel.

DC Buck Module, DROK Adjustable Buck Converter Step Down Voltage Regulator 6V-32V 30V 24V 12V to 1.5-32V 5V 5A LCD Power Supply Volt Reducer Transformer Module Board with USB Port Protective Case

The effect is similar to leaving the lights on in your car. The lights continue to burn even though there is not a power source charging the car’s battery.

Eventually, the battery goes dead. When you connect a single solar panel to a lead-acid battery, the battery acts like the lights in the car and will use all the energy in the panel until there is no more. 

It is important to note that you are still dealing with electricity, and safety should always be the first step in any solar panel project. 

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How many volts should my solar panel produce?

Do you need to know how many volts a solar panel can produce? A solar panel is not a single unit. It is many smaller units that work together. Those units are called photovoltaic cells, and solar panels come in a range of photovoltaic sizes.

The size is not the physical size of the panel, though there is that also. The size is the number of photovoltaic cells contained within the panel.

Generally, the volts your solar panels produce include:

  • 32 = 14.72 volts
  • 36 = 18 volts
  • 48 = 22 volts 
  • 60 = 27.60 volts
  • 72 = 33.12 volts
  • 96 = 44.16 volts 

Each cell produces about .47 volts. As technology improves, so will the number of volts produced by a photovoltaic cell. 

If you are trying to reduce the voltage from a solar panel to match a gadget, such as going from a 22-volt panel to a 5-volt cell phone, you will do better to replace the panel with one that matched the device. 

While a step-down converter would also work, reducing the voltage from too high to too low is a bit of overkill. 

How Many Volts Does a 200 Watt Solar Panel Produce?

A 200-watt solar panel produces 18 volts of energy, which is an ideal solar panel size for charging a 12-volt battery or to power a device that is also 12 volts.

If you need a solar panel that produced 24 volts, it would be in the 300-watt range. There is a difference in measurement between an open and closed circuit. 

  • If you had a 25-watt solar panel and wanted to charge a 12volt car battery, you would need to have 5-8 hours of direct sunlight, which is how long it would take for the panel to charge the battery.

It would likely take longer in the real world because of the ebb and flow of energy produced by a solar panel throughout the day.

The sunlight is most potent around noon. In the morning, the sunlight is weaker as it is in the later afternoon.

As the day progresses, the sunlight gets more substantial and then begins to fade. 

Voltage meter checking AC volts white background

What Is the Minimum Voltage of a Solar Panel?

It gets a bit tricky if you want to measure the minimum voltage of a solar panel. Why so tricky? Well, many things impact how much energy a solar panel can make. Those include:

  • The temperature of the panel causes a rise or drop in how many volts the panel may produce. Higher temperatures mean fewer volts. 
  • Shading and other physical interference between the sun and the panel causes drops in panel efficiency. 
  • Debris, such as dirt and dust on the solar panel, can cause a drop in the amount of energy the panel produces. 
  • Corrosion of the connections between the panel and the inverter or controller will cause a voltage drop, even more so if the panel is part of a string. 

There is also the measurement of what a volt is compared to amps and watts, which changes based on how many amps you put into the equation.

The volts also drop when you add a controller or reducer into the mix. How low is too low? You never want the voltage to drop below the rating of the batter.

A 5-volt solar panel will not charge a 6-volt battery. There will not be enough energy to charge the battery fully. 

Thankfully, there is a calculator for converting watts to volts to amps: 

So How Do You Reduce the Voltage from a Solar Panel? 

There are two ways to reduce the voltage from a solar panel. Those are:

1. Connect the panel to something that requires charging;

A lead-acid battery will take the energy from the solar panel, leaving it depleted so long as the panel is not in the sun.

Under this example, you are literally removing the voltage from the solar panel. 

2. Install a step-down converter;

Which would block a portion of the energy from the solar panel, thus reducing the voltage. The situation here occurs when you have a solar panel that safely produces more voltage than the battery can handle.

A regulator acts like a switch that shuts off the flower of energy when the battery is approaching the fully charged level.

These components help to extend the life of the battery and help to prevent overheating due to overcharging. 

In some cases, replacing the solar panel with one that matches the battery is much simpler. However, it would help if you always used a solar regulator to prevent overcharging and damage to the battery or device. 


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Elliot has 20+ years of experience in renewable technology, from conservation to efficient living. His passion is to help others achieve independent off-grid living.

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