Do Solar Panels Need Direct Sunlight?

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Jack Ayre

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Solar panels produce clean energy without dangerous carbon dioxide emissions and other dangerous gasses. Yet, if you’re already considering buying these panels, you might wonder about the effect of shady conditions on their performance. 

So, do solar panels need direct sunlight? Can they work in the shade? Is there a difference in electricity output?

We answer all these questions and more so you are in a better position to understand how solar panels work are and are able to produce electricity even on days when it is less sunny. 

Does a Solar Panel Need Direct Sunlight?

Nearby buildings, trees, and other structures might shield solar panels. So they might not be exposed to direct sunlight all day long. 

These photovoltaic panels contain light-sensitive parts, so they perform better when exposed to direct sunlight. The cells are held in place by silicone and have positive and negative sides to allow the electric current to bounce off them. Although they can still function in partial shade and don’t need direct sunlight to work all the time, they will produce maximum energy output when exposed to more photons. 

Photons are particles of solar energy that hit solar panels to generate electricity, and photovoltaic or PV cells are made of semiconductor material to change this energy into electric power. 

These photons are present in the sun’s energy. This means that your solar panels would still produce electric energy, even if they’re not always exposed to direct sunlight

Solar panels contain mirrors and reflectors to maximise the number of photons absorbed by the cells. As a result, the photons will bounce off these surfaces to provide the panels with more solar energy in the shade. 

How Does Indirect Sunlight Affect Solar Panels?

In cloudy weather, the sun’s solar energy and heat radiations are reflected off the clouds, disappearing into space. But not all clouds are the same. For example, high-altitude clouds are thinner and will allow more solar energy to pass through, so they can still power your solar panel system, despite the indirect sunlight. 

Indirect sunlight is light that has been reflected off another surface. So, while this light can reach solar panels and produce electric energy, it’s inefficient. This means that your solar panels will need more time to create the amount of electric energy they would make in direct sunlight. 

Due to its geographical location, cloud cover in the UK is pretty common! Yet, this doesn’t mean you can’t reap the benefits of solar panels. Even in shady conditions, your solar panels can still generate electric energy.

However, in these cloudy and shady conditions, you’ll have to install larger solar panels to produce the desired electric energy to power your property. A professional solar expert must evaluate the direct and indirect sunlight your roof will receive and the potential electric energy output. Professionals will also measure the amount of energy you need and estimate the time your solar panel system needs to pay for itself. 

These estimates are measured using several software tools that study the weather conditions, site conditions, and the tilt and direction of solar rays. With this information, professionals can design the right solar panel system for you. 

How Do Solar Panels Work in the Dark?

In shady conditions, like in winter and after dark, your solar panels will still be the only energy source available if you switch to clean energy. However, without any light, this will be impossible. So, solar panels won’t be able to produce electric energy in the dark. 

Thanks to a functioning battery storage system, solar panels can still power your property in the dark. This battery system stores all the excess electric energy that wasn’t used during the day. It then utilises this energy when the light conditions aren’t favourable, or there’s no sunlight at all. As a result, a reliable battery storage system will solve the shade problem if your solar panels don’t have access to direct sunlight all day. 

Moreover, the solar inverters in your solar panels change the direct current or DC to alternating current or AC. So, they can save some of the excessive efficiency loss, which is expected when the solar panel isn’t exposed to direct sunlight. 

Types of Inverters in Solar Panels

Using suitable inverters will help your solar panel system overcome the variations in electricity generation. There are three types of inverters in solar panel system layouts, and each one can solve the shade problem differently. 

Micro-Inverters

Micro-inverters are designated as one for each panel. So, if one panel is shaded and doesn’t work efficiently, the others can still produce maximum energy output. 

People usually use these inverters in larger systems, allowing the panels exposed to direct sunlight to work appropriately and produce maximum electric energy output. 

String Inverters

String inverters are more basic than micro-inverters. In this technology, several panels are connected to the same inverter, so the others won’t function properly if one panel is shaded. As a matter of fact, the system will operate at the efficiency of the weakest panel, which results in reduced energy output. 

Power Optimizers

These represent a crossover between micro and string inverters. By negating their effects, they can overcome the reduced efficiency caused by shaded panels. Moreover, they send the DC produced by the panels to a string inverter, allowing your solar panel system to operate efficiently. 

Do Solar Panels Work on Rainy and Snowy Days?

In order to operate with maximum efficiency, solar panels need to be exposed to direct sunlight. Unfortunately, this might not be possible on rainy days. 

However, this doesn’t mean your solar panel system will stop operating when it rains. These systems are perfectly insulated and can safely operate in heavy rain. 

Yet, the performance of your system is expected to decline. For example, you can expect a lower performance by 40% to 90%, depending on the heaviness of the cloud cover. 

On the other hand, some rain can actually benefit your solar panels as it can remove dirt and dust which can impact on the performance levels of your solar panels. Dust accumulation will affect the quantity of light that passes through the panels to produce electric energy.

Dealing with snow is different matter. First, the sunlight can pass through a light layer of snow, so your system can still operate and produce electric energy. Moreover, the snow will cool off the system, protecting it from overheating and negatively impacting its efficiency. 

However, heavy snowfall is a different story. It can obstruct sunlight and deprive your solar panels of access to the daylight it needs. 

Nevertheless, due to the design of solar panels, snow will often slide off and won;t always build up to obstruct the light. Moreover, as the snow melts, it can remove some of the dust buildup and improve the efficiency of your solar panels. 

Does the Amount of Sunlight Affect the Size of My Solar Panel System?

Your solar panel system’s size depends on how much solar energy it receives to produce electric energy. So, based on the weather conditions and peak sun hours in your region, a professional will decide on the right solar panel system size to power your property. 

In a region with more sun peak hours, a smaller solar array might be sufficient for your property. Since the panels will operate more efficiently, you won’t necessarily have to invest in a larger system. 

However, in the UK, people usually go for larger systems and combine it with a solar battery to get the most from their solar PV system. 

 

Solar FAQs

  1. Which Solar Panels Will Work Best in the Shade?

Solar panels equipped with micro-inverters or power optimisers will operate best in the shade. However, they don’t limit the whole system’s capacity to the efficiency of the lowest-operating panel. So if one panel is shaded and doesn’t produce enough energy, the other panels can still operate efficiently. 

String inverters aren’t that useful in shady conditions. If one panel is shaded, the whole system’s performance will be impacted. 

  1. What Time of the Day Do Solar Panels Reach Their Maximum Output?

Solar panels produce maximum electricity output when they function in direct sunlight. The peak sun hour refers to the amount of solar energy that solar PV receives in one day. 

The peak hours for solar radiation are between midday and early afternoon. During this period, your solar PV will receive the largest amount of energy to produce electricity. Every solar panel system needs at least 4000 watt-hours over a day to reach its peak energy production output and pay for itself. 

Solar Power Production Summary

Solar panels operate efficiently in direct sunlight, as the photons hit the PV cells in the panels and then get transformed into electric energy. However, these panels don’t need direct sunlight, as they can still operate in indirect sunlight. 

Indirect sunlight will affect the solar panels’ performance, reducing their efficiency. However, most systems can overcome this problem with the help of solar batteries that store unused energy and inverters. 

There are different types of inverters, but the best ones are the ones that don’t allow the performance of a shaded solar panel to affect the whole system’s performance. Your solar panel system can still operate on rainy and snowy days, but its efficiency depends on how cloudy it is. Nevertheless, the rain and melting snow can help remove the dust buildup on your panels, improving their ability to utilise sunlight. 

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Born in North West England, Jack kicked off his career in the insurance arena, dealing with claims for three years. Always up for a challenge, Jack leapt out of his comfort zone and embarked upon 5 years of excitement with the military.

Working for the Ministry of Defence, Jack specialised in counter-terrorism which took him to places such as Dubai, Oman, Iraq, Norway and Bahrain. During this period he worked with various Governments implementing strategic operations to prevent terrorism.

After travelling around various countries Jack increasingly came across various forms of solar from large solar farms to domestic solar panels. From here Jack took a keen interest in all things solar and started reading about the technological capabilities with a view to entering the industry after his career in the Ministry of Defence.

Once home after 5 fruitful years, Jack had 3 months leave in which he immersed himself in a solar crash course and got applying for jobs within the solar sector. He came across ESE Solar, a long-established forward-thinking company whose head office was only a stone’s throw away from him. He picked up the phone to see if there were any vacancies and within a week had a successful interview and obtained a full-time job, starting in the technical team.

Within the first few months, Jack onboarded in various online courses during work and social hours to speed up his knowledge of all things solar. Due to his strong work ethic and thirst for knowledge Jack was promoted to Head of Technical at ESE Solar. He currently leads the team and oversees the product development of new technologies within the company alongside assisting where necessary on their maintenance department.

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