100-Watt Solar Panel Output On Cloudy Day

A 100-watt solar panel produces 10% to 25% electricity on a cloudy day. But on a rainy day, the production rate can decrease by 10% because of the lack of direct sunlight. You can expect a maximum of 6 amp-hours of electricity per day. 

Ever noticed how your 100-watt solar panel goes out pretty soon on a cloudy or rainy day? I’m sure you did. That’s because the photovoltaic cells of a solar panel produce less electricity on a cloudy day. 

A 100-watt solar panel produces significantly less electricity on highly cloudy and rainy days. Here in this article, I will discuss the output of a 100-watt solar panel on a cloudy day. 

At the end of it, I will show what other factors affect the output of a 100-watt solar panel. So, stay with me here because we are about to start. 

How Much Does A 100-Watt Solar Panel Produce On A Cloudy Day?

As much as we love a cloudy day, it’s not very productive for any solar panel, let alone a 100-watt one. Solar panels depend entirely on daylights or sunlight, and clouds block sunlight. As a result, cloudy days are dark.  

We already know that 100-watt solar panels can produce up to 30 amps-hour per day. But on a cloudy day, it will be significantly less since the sunlight is not adequate. It can produce 10% to 25% less electricity on such days. 

You will get around 1.2 amp per hour or about 6 amps-hour per day on a cloudy day. The electricity production will be far less on heavy rainy days. 

You can expect only a 10% production rate on such days. So, it can be challenging to get going with a 100-watt solar panel on cloudy or rainy days. 

100-Watt Solar Panel Voltage on Cloudy Day 

There is a misconception that solar panels do not work on cloudy days, but it’s not entirely true. Yes, cloudy days reduce the conversion rate of a solar panel, but it does not just stop working. 

A 100-watt solar panel is already a small one and produces enough electricity to charge devices like phones, laptops, and home appliances. But on a cloudy day, it produces significantly less electricity. You will get around 1 or 2 amp per hour from a 12-volt battery. 

On a rainy day, it even produces less electricity. So, a 12-volt battery will take a long time to charge fully, and there is a chance any of your devices will take far more time to be charged. 

Solar Panel Cloudy Day Efficiency

We already know solar panels cannot work up to their total capacity on cloudy or rainy days. Instead, they provide significantly less electricity these days. It is a drawback of solar panels since it’s entirely dependent on the sun for generating electricity. 

But it does not just stop working. Since you need light for solar panels, cloudy or rainy days do not just become dark. Some lights remain, and the PV cell of the solar panel uses it to make electricity. 

So, the efficiency goes down on a cloudy day, but it does not just become zero. It still produces electricity. But you will need more time to charge any of your devices with a 100-watt solar panel when the environment is cloudy and when it rains. 

Do 100 Watt solar panels generate enough power on cloudy days? 

We already know that no solar panel can generate enough power on a cloudy day. Because of the lack of light, the conversion rate goes down significantly. Similarly, a 100-watt solar panel produces only 25% of its capacity. 

It is, of course, not enough by any means. You won’t be able to charge your smartphone with this amount of electricity properly. So, it’s clear that 100-watt solar panels do not produce adequate electricity on cloudy or rainy days. 

In this situation, you can do one of two things. You can replace your 100-watt solar panels with cloud-day compatible solar panels or add more solar panels and expand your solar energy system. This way, you can ensure enough electricity even on a rainy day. 

How Can Solar Energy Still Be Collected On Cloudy Days?

We already know that solar panel works on cloudy days. But you may be wondering how it still works when the sun is not visible. You will get your answer if you think about the people who get sunburned on cloudy days. 

Sunlight can penetrate clouds. As a result, solar panels work pretty well on regular cloudy days. People think solar panels need direct sunlight to generate electricity. But it’s not entirely correct. They can absorb particles from indirect sunlight. That’s why they can generate power from lights coming through clouds. 

Solar panels absorb the light from the clouds, and the photovoltaic cells convert it into Direct Current (DC). Then your inverter turns it into an Alternative Current and makes it compatible with your devices. 

A lot of people think solar panels need heat to produce power. That’s not true at all. In fact, the solar panel works best on sunny and cold days. Because colder weather helps solar panels produce more electricity. 

All in all, solar panels generate electricity on cloudy days, even on rainy days. But of course, the electricity production rate will be reduced to a certain percentage. 

What Can You Power With One 100 Watt Solar Panel On Cloudy Day?  

 A 100-watt solar panel can power and charge many small devices on a sunny day at its highest capacity. You can charge your laptop, phone, tablets, watches, etc., devices with it. Besides, it also can run your TV, WiFi, Fans, Lights, etc., with a 100-watt solar panel. 

So, it won’t be enough for running an entire RV, or you cannot run your refrigerator or washing machine with it. You will need multiple 100-watt solar panels to run your entire RV or house. Increasing the wattage will help as well. 

But on a cloudy day, you will surely struggle. We know that a 100-watt solar panel produces significantly less amount of electricity. So, you will be able to run many of the small devices I’ve mentioned earlier, but you might have to use one at a time. 

If you don’t want to face such a situation, you will have to use more than one 100-watt solar panel, a better battery, and converter, or a solar panel with more wattage. That way, you can avoid many unexpected situations where you will have to go through blackouts on cloudy or rainy days.

What Other Factors Affect the Output Of A 100-Watt Solar Panel? 

Apart from clouds or rain, some other factors can affect the performance of a 100-watt solar panel. Before jumping to the conclusion that the cloud is responsible for reduced performance, you should check whether the following things are working correctly. 

Solar Panel Type 

We know that monocrystalline solar panels are better for cloudy weather. So, if you live in a place where clouds or rain are a regular occurrence, you should use a monocrystalline solar panel. However, polycrystalline solar panels are best for hot climates. 


Temperature is another factor that affects the performance of a 100-watt solar panel. Cold but sunny weather maximizes the output of a 100-watt solar panel. On the other hand, hot water reduces the solar panel’s output. 

Sunlight Duration 

The duration of sunlight your solar panel is receiving also determines how much electricity it will produce. So, make sure you mount the panel where it receives maximum sunlight.


Ghazi, S. I. (2014 ). The effect of weather conditions on the efficiency of PV panels in southeast of UK. Researchgate, 50-59.

How Much Power Can Solar Energy Generate on a Cloudy Day? (2021, January 15 ). Retrieved from Sunergy Systems: https://sunergysystems.com/how-much-power-can-solar-energy-generate-on-a-cloudy-day/ 

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