How Much Power Does a 120w Solar Panel Produce? (Amps, Volt)

Curious to know how much power a 120-watt solar panel produce? how many amps, volts, and watts in a day? 

So in this article, I’ll explain how much power you’ll get from 120w solar panels in a day according to your location.

On average, A 120-watt solar panel will produce about 100 watts of power output per peak sun hour. And 0.5-0.7kWh of total energy per day. The exact value will depend on the number of peak sun hours your location receives

Need a simple solution? Use my free solar panel output calculator

How Solar Panels Are Tested? – STC

First, let’s discuss how the manufacturers give the wattage rating to any solar panel.

The solar panels are designed to produce their rated power output under Standard Test Conditions (STC). 

This includes the intensity of the sunlight as 1000 watts per square meter, Temperature 25℃ or 77℉, and no wind

So in the real world, it’s rarely gonna happen when you’ll receive the 100% rated wattage output from your solar panel. 

Now let’s discuss some factors which will affect the power output of a solar panel.

Before going further watch this video to understand the basics of electricity (Watts, volts, and amps)

What Are Peak Sun Hours? How To Calculate?

  • 1 peak sun hour = 1000 watt/ meter2 of sunlight intensity 

As we already have discussed under which conditions the solar panels are designed to produce their rated wattage output

That is why the number of peak sun hours is considered as the baseline when estimating how much power any solar panel system will produce.

How To Calculate Peak Sun Hours?

Every location receives a different amount of total solar radiation per day. Luckily some geniuses have gathered this information and made it easy for us.

Use this PV solar peak sun hour calculator to find out how many hours of peak sunlight your city receives.

Step 1: Enter Your Address

Enter your complete address or just simply mention your city

How to calculate peak sun hours

Step 2: Select Results

How to calculate peak sun hours
How many peak sun hours in florida?

Now this will be the number of total solar radiations your city/house receives per day month by month. 

As you can see i live in Florida city, and here we receive about 4.8 – 6kWh/merter2 of solar radiation (4.8kW in winter and 6kW in summer)

I would have to place my solar panels all day to get these number of peak sun hours.

Now let’s discuss the average solar panel output during peak sun hours.

Average Solar Output During Peak Sun Hours

Peak Sun Hours

On average you’d receive about 80% of rated wattage output from your solar panel in a peak sun hour. For Example, a 100 watts of power output from a 120-watt solar panel 

The average value is based on my personal experience with my 200-watt solar panel. The average percentage is based on 30 days of output data.

The 20% less efficiency rate will occur due to the changes in weather conditions, some power losses in wiring, & because the charge controller

Related Post: Solar Panel Output Calculator – Average Solar Panel Output?

120-watt Solar Panel Output – Calculation

I would take my location as an example and the average annual number of peak sun hours (5.8)

First of all, let’s multiply the power panel-rated wattage by the number of peak sun hours per day. 

120 * 5.8 = 696Wh 

Now multiply the value by 0.8 

696 * 0.8 = 556 watt-hours (Wh)

120-watt solar panel will produce about 550 watt-hours of DC energy per day in Florida

120-watt Solar Panel How Many Amps?

An ampere or amp is the basic unit of electric current according to the international system of units.

The panels are rated in watts ( Watts = Amps * Volts ).

So to calculate the value of amps we use this formula (amps = watt/volts)

A 12v 120 watt solar panel will produce about 18 volts and 6.6 amps under ideal sunlight conditions (inc. 1kw/m2 of sunlight intensity, no wind, and 25oC temperature)

Related post: Solar Panel Amps Calculator (Watts to Amps)

AC vs DC watts 

Solar panels produce power in direct current (DC), batteries also store power in DC but most of our household appliances required AC (alternating current)

So to convert DC into AC, we use an inverter. And like the other electronics, the inverters are not also 100% efficient. 

Most of the inverters available right now are about 85-90% efficient

This means there will be a 10-15% percent power loss when converting DC into AC. 

Let’s convert the above calculated DC value into AC based on a 90% efficient inverter.

550 * 0.9 = 4995 watt-hours (AC)

I have discussed this in detail about this topic, Read the below-mentioned article for more in-depth information 

Related Post: Solar DC Watts To AC Watts Calculator

What can a 120w solar panel run?

120-watt solar panel can produce enough power to run most of the basic appliances like a fridge for a few hours, Tv, laptop, phone, LED bulbs, Fans, etc… with the help of a battery during camping or in case of any emergency. 

Here’s a chart of appliances and their wattage consumption and for how many hours you can run them on a 120w solar panel and a battery bank.

What Size Battery For 120 Watt solar panel? 

You’d need a 12v 100ah lead-acid or 12v 50ah lithium battery with a 120-watt solar panel. 

To calculate the size of a battery bank, multiply the average output of your solar panel by the higher number of peak sun hours (by month using the above calculator) and then divide it by 12 for a 12v battery or 24 for a 24v battery bank 

And also you’d need a 15A charge controller to charge the battery with a 120-watt solar panel. 

Or instead, you can use a portable power station, this way you’d not have to worry about any wiring stuff and it’s easy to carry on and best for on-the-go solar power.

I would recommend a jackery explorer 1000 portable power station with a 120-watt solar panel 

Related Post: Jackery Explorer 1000: An Owner’s Review

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I'm an experienced Sales Consultant with a demonstrated history of working in the renewables and environment industry. Skilled in Photography, Customer Service, and Sales.