Knowing how much power a solar panel can produce is important when considering whether or not it’s the right choice for your energy needs.
So, how many amps does a 100-watt solar panel produce?
The answer to this question is not so straightforward and depends on several factors, such as the Voc (open circuit voltage), the temperature coefficient, and the climate you live in.
But in general, a 100W solar panel can produce about 3.5A.
In this article, I’ll walk you step by step through the calculation process, so you can determine exactly how much power your solar panel is able to produce.
- Solar panels are rated by their wattage output which is the amount of power they produce for every hour of 1,000W/m² sunlight they receive
- The amount of current the solar panel produces depends on Vmp and the wattage of the panel
- A 100W solar panel with Voc of 23.85V and Voc temperature coefficient of -0.28V has a Vmp of 28.4V
- A 100-watt solar panel that has a Vmp of 28.4V will produce 3.5A of current for every peak sun hour it receives
- For 5.8 peak sun hours per day, a 100W can produce 20.3Ah
How Are Solar Panels Rated?
Before we get into the specifics of how many amps a 100-watt solar panel produces, it’s important to know how solar panels are rated.
Solar panels are typically rated by their wattage output, which is the amount of energy they produce under Standard Test Conditions (STC).
To rate the wattage output of a solar panel, manufacturers measure its efficiency under laboratory conditions that simulate full sun.
In this test, they put the solar panel at 25°C (77°F) and 1,000W/m² irradiance with a 1.5 Air Mass rating.
Then they measure how much energy the solar panel produces in watts over the course of an hour.
The wattage output number they come up with is the rating that goes on the solar panel’s label.
So, a 100-watt solar rating means that the panel will produce 100wh of energy for every hour of 1,000W/m² sunlight it receives.
How Many Volts Does a 100-Watt Solar Panel Produce?
To calculate how many amps a 100-watt solar panel produces, we first need to know the voltage rating of the panel.
We need here the Vmp (Voltage at Maximum Power) rating of the solar panel, which is the voltage that produces the most power.
You can find this number on the panel’s label or datasheet.
But if you want to calculate it yourself, you can use this calculator.
I live in California and I’m using one 100-watt monocrystalline solar panel, so I chose the following parameters for the calculator:
- Voc (Open Circuit Voltage): 23.85V
- Number of solar panels in series: 1
- Lowest expected temperature: -45°F
- Voc temperature coefficient: -0.28V
The result I get from the calculator is Vmp = 28.4V
How to Calculate the Number of Amps a 100-Watt Solar Panel Produces?
We now know the Vmp of our 100-watt solar panel, which is 28.4V.
To calculate how many amps the panel produces, we simply divide its wattage by its voltage rating:
Amps = Watts / Volts
Amps = 100W / 28.4V = 3.5A
So, a 100-watt solar panel that has a Vmp of 28.4V will produce 3.5A of current for every peak sun hour it receives.
To know the total amount of current your solar panel is producing during the day, you just need to multiply this number by the actual peak sun hours it receives.
Since I live in California, I can look up this number on the National Renewable Energy Laboratory’s calculator.
For Los Angeles, it says that the peak sun hours per day are 5.8 hours.
So, my 100-watt solar panel will produce:
Current (Amps) = 3.5A x 5.8h = 20.3Ah of current per day.
This is enough solar power to run a fan and a few lights for around 8 hours per day.
Also, keep in mind that you may not get this exact number due to other factors such as shadows, shade, and dust.
Why Is It Important to Calculate Amps?
Simply put, amperes are the unit of measure for electric current, which tells you how much power is flowing through a circuit.
Knowing the amperage of your solar panel will help you determine the type and size of components you need for your systems, such as charge controllers and batteries.
Appliances also require a certain amount of current to work which you can use to calculate the number of solar panels you need for your system.
For example, if you have a device with 12Ah of current, this means it will draw 12A of current for 1 hour.
And if you plan to run it for 4 hours, you will need 48A of current.
To get this amount of current, you will need four 100-watt solar panels connected in parallel:
Current (Amps) = 4 x 3.5A = 14A of current for each hour your device is in use.
So, as you can see, calculating the number of amps a solar panel produces is essential for designing your solar system for shed.
What Size Charge Controller Do I Need for a 100W Solar Panel?
Connecting your solar panel directly to a battery can overcharge it and damage the battery.
So, you need to use a charge controller in between them to regulate the current and prevent overcharging.
To calculate the size of the charge controller you need, you can use this calculator.
For my system, I opted for these parameters:
Solar panel wattage: 100W
Battery voltage: 12V
Voc of solar panel: 23.85V
The calculator estimates that I need a 10.4A charge controller for my 100W solar panel.
I recommend you go with MPPT charge controllers as they are more efficient than the PWM counterparts.
How Many Amps Can a 100W Solar Panel Produce?
A 100W solar panel that has a Vmp of 28.4V will produce 3.5A of current for every peak sun hour it receives.
How Many Amps Does a 12V 100W Solar Panel Produce?
A 12V, 100W solar panel will produce 8.3A of current for every peak sun hour it receives.
How Long Will a 100-Watt Solar Panel Take to Charge a 12V Battery?
A 100-watt solar panel connected to a 12V battery will take about 7.4 peak sun hours to fully charge the battery.
Knowing the number of amps a solar panel produces will help you make sure your system is designed correctly and running efficiently.
Do you still have questions about calculating amps for your solar panel?
If so, please leave them in the comments section below.