Do Solar Panels Work on Cloudy Days?

By Kami Turky

Last Updated:

The increasing popularity of solar energy and turning hundreds of people into solar panels is quite remarkable. 

But also this has caused a common question among folks, whether solar panels work on cloudy days or not?

The answer is yes. Solar panels can still generate electricity on cloudy days, even though the output may be lower.

In this article, I’ll walk you step by step through understanding how solar panels work on cloudy days, how to store electricity, and much more.

So, without further ado, let’s dive right in.

Key Takeaways

  • Solar panels can work on cloudy days but they will be less efficient.
  • On a gloomy day, the solar panel can generate only 10%-15% of its normal output.
  • Solar panels don’t work at night as they convert sunlight into electricity but don’t store it.
  • You can store electricity produced by panels either by batteries or net metering.
  • Net metering allows you to store your solar energy and take credit for the excess electricity that’s generated back to the grid.

How Do Solar Panels Work?

Before we get into how solar panels work on cloudy days, let’s quickly go over how they work in general.

Solar panels are made up of several photovoltaic (PV) cells that absorb energy from the sun and convert it into electricity.

The PV cells are sandwiched between two thin layers of a semiconductor material such as silicon.

Each layer has a different electrical charge and when the sunlight hits them, the photons in the sunlight knock electrons free from their atoms in a phenomenon known as the photovoltaic effect.

The electric field created by the two layers then pulls these electrons away, creating an electrical current.

This current is a direct current (DC) and needs to be converted into an alternating current (AC) in order for it to be used in the house.

This is done via an inverter which changes the DC into AC and sends it off through your electric panel, which powers your home.

Do Solar Panels Work on Cloudy Days?

Solar panels can still operate even when it’s cloudy, though not as efficiently.

Clouds block some of the sunlight and reduce the amount of energy that reaches the solar cells.

The panels will generate about 10%-15% of their normal output on a cloudy day depending on how thick the clouds are and the efficiency of the panels.

For example, if you have a 400W panel that generates about 1,761 Wh a day on a sunny day, it will generate about 176-264 Wh a day on a cloudy day.

I live in Montana and you know how cloudy the skies can get here.

My solar panels have still been able to generate enough energy for me even on the cloudiest days, so I know that it’s totally possible.

It just takes a little bit more planning and opting for higher-efficiency solar panels with high watt ratings.

Do Solar Panels Work at Night?

Solar panels do not work at night. Photovoltaic cells need sunlight to produce electricity and without any light, the solar panels cannot generate power.

In other words, solar panels only convert light energy into electrical energy, but they don’t store energy.

However, this doesn’t mean you can’t use solar energy at night – many households install battery backup systems to store energy during the day so they can still access it after dark.

For my 500W panel, I’ve installed a 12V 230Ah battery – it’s enough to power my house for 8 hours after dark, even on cloudy days.

How to Store Solar Energy to Use on Cloudy Days or at Night?

There are two main ways to store solar energy – battery backup systems and net metering systems.

Let’s start with battery backup systems.

During peak sun hours when the solar energy is at its highest, the solar panel harnesses the energy and converts it into electricity.

Then, a charge controller regulates the current between the solar panel and the battery to ensure that the panels don’t overload the battery.

The excess energy is then stored in the battery for later use.

This makes it so that you can still access and use your solar energy even when it’s cloudy or at night.

To calculate the size of your battery, you can use this equation:

Battery Size (Ah) = Solar Panel Daily Output (Wh) / Battery’s Voltage (12/24V) / DoD (0.5/0.75/0.8)

If we assume you have a 500W panel that generates about 2,537 Wh a day and you want to use a 24V battery with 80% DoD, the equation will be:

Battery Size = 2,537Wh / 24V / 0.8 = 132Ah

So, you will need a 132Ah battery to store the energy from your 500W solar panel and have enough energy to power your home at night.

Net metering hits two birds with one stone – it not only allows you to store your solar energy, but it also allows you to sell the excess electricity that’s generated back to the grid.

But how does net metering work exactly?

When the sun is shining, your solar panels will generate more electricity than you need and this extra energy will go back into the grid.

As a result, your electricity meter won’t move forward, it will actually spin backward – which means you’re being credited for the energy that you’re giving back.

This energy credit can then be used to offset the energy that you pull from the grid at night or on cloudy days when your solar panels aren’t producing as much energy.

The only downside with net metering is that not all states offer it, so you’ll need to check with your utility provider to see if it’s an option for you.

You can also look into other programs that are offered in the US such as Solar Renewable Energy Certificates (SRECs) or virtual net metering.

These programs can help you monetize your solar energy and make the most out of your system.

Actually, my state supports net metering but I still prefer to keep a battery backup system for my 400W panel – it gives me more control over when and how I use my solar energy.

FAQs

Do Solar Panels Work With Moonlight?

Solar panels work with moonlight. Moonlight is a reflected form of sunlight and it has enough energy to generate electricity.
However, the efficiency of solar panels in the moonlight is only 0.3% of what they can produce when exposed to direct sunlight.

What Kind of Solar Panels Work on Cloudy Days?

Monocrystalline solar panels are the most efficient when it comes to working on cloudy days.

How Much Power Does a 100-Watt Solar Panel Produce on a Cloudy Day?

A 100-watt solar panel produces about 10-20 watts of power on a cloudy day, depending on how dense the clouds are.

Do Solar Panels Work in Shade?

Solar panels work in the shade, but they are less efficient. When the cells are blocked from the sun by shade or clouds, they can’t create as much energy.

Conclusion

As promised, we have now gone over the basics of how solar energy works, if solar panels work on cloudy days, how to store solar energy, and how net metering works.

Just remember that when it comes to solar energy, you have options and there are other alternative programs that can help you make the most out of your system.

Do you still have questions? If so, feel free to drop a comment and I’ll do my best to answer them.

Kami Turky

Kami is a solar engineer with nearly a decade of experience in researching, testing, and reviewing various solar products.He has also provided technical consultation to several organizations on the best ways to incorporate solar energy into their operations.When he’s not busy helping others find the best solar solutions, Kami enjoys spending time outdoors, hiking, camping, and exploring the natural wonders of his home state.

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