Are you currently overpaying for electricity in Virginia?

Enter your zip code to save on your electric bill!

Do You Need Direct Sunlight for Solar Panels?

how many hours of sun do solar panels need

Solar panels work in all conditions, not only when there is direct sunlight. However, as their efficiency can be reduced quite quickly, especially in conditions when the sky is overcast or there is a lot of dust, this does not mean that you should install solar panels just anywhere. Although they will produce electricity, installing solar panels in the right spot and at the perfect angle will improve their efficiency, reduce your energy bill, and will minimize the payoff period. 

The thing is that most solar panels need direct sunlight to generate electricity. This is because your solar panel system was designed to convert photons, particles that make up sunlight, into current – as they hit the surface of the solar panel, they excite electrons and make them move. This is what creates the current that your home devices and appliances use. 

Indirect sunlight, on the other hand, also contains photons, although their number is much lower, especially because they are more dispersed. Clouds, humidity, and dust can reflect some photons back to space, and others are sent in many different directions, rather than a single direction – toward your panels. 

A combination of both direct and indirect sunlight is what most solar panels are exposed to during an average day. No day is without a single cloud and no year is without a rainy period. All this means that your solar system will be producing different amounts of electricity during different parts of both a year and a day, but will be enough to produce enough renewable energy for your home. 

What is a Solar Panel?

A solar panel is a device that is mounted on the rooftop. It uses direct and indirect sunlight to create electricity. This solar electricity is then converted from DC – Direct Current – to AC – Alternating Current – that your domestic devices can use. Solar panels installed on your rooftop consist of many smaller elements called solar cells. 

A solar panel consists of dozens of solar cells. Each of these cells is a device in its own right and can produce energy on its own. Small solar calculators and other small solar-powered devices contain small solar cells – you must have seen them at least once before. However, as solar cells produce very little energy, many of them are arranged in your solar panel. 

This way, solar panels produce cumulative energy generation and decent power output. Solar technology also has other technology solutions that accompany it – and ensure that your panels reach maximum efficiency for the highest possible part of the day. The technology is actually so advanced, that only four hours of direct sunlight are enough to ensure solar power production for an average day. Even the Amish use solar panels – so why not you?

This is an average day in a year. Make sure you understand that cloudy days, rain, snow, dust, shade or partial shade, and sun angles can heavily influence power production. However, by choosing the right type of solar panels, you can offset some (but not all) of these issues. There are several types of solar panels: 

How Does it Work?

Sunlight contains photons that excite electrons in solar cells. This happens in any of the solar panel types outlined above and is how solar panels function. OThe electrons that are excited need to leave the solar panel quickly, or they will go back to their resting positions as soon as shade hits the panel. 

However, indirect sunlight also contains photons. It has way fewer of them, so electricity production is going to be much lower. However, there will still be some energy production even with indirect sunlight. Overcast skies will generally reduce energy production by around 10-60%. A cloudy day with rain, on the other hand, will reduce energy production in all solar systems by up to 90%. This does not mean that you will not have enough energy for your home, especially if you live in an area where net metering is available. 

Energy generation during a full moon and from street lights is also not unheard of. Energy generated during a full moon will be enough to run a small fridge with a large solar system. On the other hand, electricity production from streetlights will be just high enough to maybe charge a phone. All this should show that solar panels can draw on light coming from any source and that the energy production of the sun’s rays will result in the highest energy output. 

Every solar panel system has an inverter as well, and this inverter is a necessary part of your solar system. This is because your solar panels produce DC current – the type of current that your home appliances cannot use. A solar inverter converts this type of current into AC – which your appliances can use. 

As we will see later on, there are different kinds of solar inverters: 

  • String inverters, 
  • Micro inverters, and 
  • Power optimizers. 

If you have an entire solar energy system that includes a solar battery as well, you should know that solar panels should never be connected directly to the solar battery. Connecting them to the battery directly can damage them, as the incoming current is highly variable and may even be too strong at times. This is why all solar systems with a solar battery have a solar charge controller as well. 

This device controls the incoming current and irons it out – reducing the strain on your battery and the power fluctuations. They should be paired with a good set of batteries, such as the Tesla Powerwall. However, you should be careful and reserve batteries if you need a backup power supply or for off-grid applications, as they will increase the solar payback period. 

Solar Panel Energy Generation

Solar panel energy generation is at its highest, the peak energy production, in ideal conditions. These conditions mean that the panels are exposed to direct sunlight falling at the right angle and that they are of sufficient strength – usually during the warmer period of the year. These conditions also mean that the solar panels absorb most of the sunlight that falls onto them, as there is no shade. Shaded solar panels produce much less energy and can sometimes even act as power users. 

Factors to take into consideration to better understand your solar system energy production in both direct and indirect sunlight are: 

  • The availability of direct sunlight, 
  • Duration of shade, 
  • Solar panel technology (regular or half-cut solar cells), 
  • Inverter setup and kind of inverter, 
  • Weather conditions, including: 
    • Cloudy days, 
    • Rain, and 
    • Snow. 

Direct Sunlight

The best of the ideal conditions is direct sunlight. Under direct sunlight, your solar panel system will reach its peak production. It will produce the highest possible amount of electricity for as long as the sun is shining. Direct sunlight, for this reason, is one of the best conditions that your solar panels can be exposed to. 

However, direct sunlight will also reduce the efficiency of your solar panels. This is because exposure to sunlight will increase the temperature of your solar panels quickly, and with higher temperatures, they will lose a part of their efficiency. However, mild wind can help keep this temperature at ideal conditions. The same goes for lower temperatures during the spring and the autumn, while sunny winter days may still see a reduction in the energy produced, especially as the angle the sunlight falls down to is too low for good energy production. 

So, direct sunlight falling onto panels at the right angle or as close to it as possible is the best sun exposure. Although the temperature of the panels may get too high, this is still considered optimal. Some solar panels, such as hybrid solar panels, or agrivoltaic systems, use the cold water/air beneath them to boost energy production. 

In the Shade

Solar panels generate electricity the best when in full sunlight. However, this is not always possible. If you live in a heavily wooded or urban area, you may have noticed that your roof is shaded for at least a portion of the day. Not getting enough sunlight in the mornings and evenings is a common problem, but for as long as you get an average insolation of 4 hours a day, you should be ok. Half-cut solar panels are more resistant to shading than whole-cell panels. 

Duration

Any shading that is long can pose a problem. You should pay special attention to the kind of inverter you have, as not all inverters can handle shading the right way. In fact, using micro-inverters will result in power loss only in shaded solar cells and panels. Using other kinds of inverters will result in overall system power loss. 

Solar Panel Technology

Solar panels technology also has a say in the solar panel output that you can receive even in shaded areas. As the energy output should be kept as close to maximum as possible, you can opt for highly efficient monocrystalline solar panels. Half-cut solar cells are better suited to shaded areas and can reduce power losses, especially during mornings and afternoons. 

Inverter Setup

The inverter setup in shaded areas is also very important, especially as it can significantly reduce power loss in shaded areas. Solar panels with micro inverters can reduce power loss and limit it to shaded solar cells and solar panels only. If you have a single inverter, a part of the energy the solar panels absorb will always be lost if there is shade even on a portion of the solar system, even during the peak sun hours when excess energy should be sent to the grid. 

Weather Conditions

On the other hand, weather conditions can also influence the ability of your solar panels to generate electricity, as does dust. Solar panels work best in direct sunlight – which means no clouds in the sky. Indeed, clouds, rain, snow, and even dust can influence the performance of your solar panels. 

Cloudy Days

To work at its peak performance, your solar system needs a clear sky. The sun’s rays can hit the panels unobstructed and bring their energy output to the maximum. Solar panels perform best on bright, clear, spring and autumn days. Summers can be a bit too hot, and winters can bring in a lot of snow. 

Rain

Rain always means overcast skies and less light coming down to the panels. In fact, heavily overcast skies can reduce the sun’s energy and solar power output by as much as 90%. This is why cloudy weather usually sees a reduction in generation capacity. Even the best solar panels are prone to losing their efficiency, but no worries: as soon as the clouds disperse, the power generation resumes at full capacity. 

Snow

On the other hand, snow can cover solar panels and reduce their efficiency even if subsequent days are sunny. This does not mean that your panels will not produce any solar power, as it takes deep snow to completely block the sunlight. An added benefit of snow on top of your solar panels, especially if the snow is light is that: 

  • At first, the snow will keep the panels at a comfortable temperature and will enable them to work at peak performance for a longer time. Solar panels need cooler temperatures, which is exactly the reason they can lose some of their efficiency during the dog days of summer. 
  • Secondly, your solar panels will be cleaned by the snow and ready for springtime. As the layer of the snow closest to the panels melts, the snow will slide down, taking with it any dust particles and leaves which may have fallen onto the panels during the autumn. 

Both snow and rain have an added benefit to them: they clean your panels. Although you may lose some of the efficiency during the day when it rains or snows, the upcoming days will see an increase in the energy output, as even the best solar panels require clean glazing and clear skies. So, bad weather conditions can influence both older and newer solar panels in a good way, by increasing their maximum output. 

Solar Batteries

Most solar systems do not need solar batteries. However, to be able to install panels and use that same energy in an off-grid setting, you need a solar battery. Using solar energy only when it is produced is not convenient and may even damage some of your devices. Generating electricity at maximum output, using some of it, and storing the remaining energy enables you to be much more efficient. 

However, installing solar batteries to reduce how much energy is wasted can cost a lot. In some cases, it can even double the initial cost of the investment. However, this can give you more comfort in an off-grid setting and even if you were on the grid, a solar battery can significantly reduce your dependence on the grid. It can also significantly decrease your electric bill. 

Types of Inverters Used in Solar Energy Systems

As solar panels are exposed to direct sunlight, your solar energy system will produce DC current. However, as your home devices cannot use this type of current, you need an inverter. As always, choosing the right type of solar inverter is crucial, as some can help you overcome the issue of partial or full shading. There are three basic types of inverters: 

  • String inverters, 
  • Micro-inverters, and 
  • Power optimizers. 

String Inverters

String inverters are the most basic type of inverter there is. When generating electricity, solar panels send the electricity to the inverter, but partially or fully shaded panels send less. In some cases, they can even act as power users in a solar setup. Cloudy weather with a string inverter, for example, will significantly reduce the power output, even during peak sun hours. 

Micro-Inverters

Micro-inverters, on the other hand, can help overcome the issue of how much direct sunlight is converted into energy, even with partial shading. This is because shaded panels produce power of a lower amperage, but the microinverter (typically installed on every solar panel) cannot interfere with how much energy the overall system produces. In a setup like this, your solar panel system will produce enough power even partially shaded. 

Power Optimizers

Power optimizers, on the other hand, use different technology to achieve the same effect as micro-inverters. Power optimizers are a combination of string and micro-inverters. They can annulate the negative effects of partial shading and can provide a higher power output for the entire system. In a power optimizer, the final instance that energy passes through is a string inverter, before it is sent to the home. 

Tips to Increase Solar Panel Efficiency

will solar panels work in the shade

As with any other device or appliance, there are ways to increase the efficiency of solar panels. Although they have many advantages to offer, as solar panels work, they get dirty, the sun moves, and the greenery keeps growing during the 25 years that your solar panels are expected to work. Here are some tips to keep your solar panels at their peak performance: 

  • Always install solar panels in the best, sunny location, 
  • Install panels at an optimal angle, 
  • Remove any obstructions, including trees and anything else that can shade them, and 
  • Install a solar tracking system. 

Install Solar Panels in the Best Location

Installing solar panel systems in the best location means that they should face south in the Northern hemisphere, or north in the Southern hemisphere. In the equator, your panels should face upwards. As the US is in the Northern hemisphere, all panels should face south. This will provide them with enough direct sunlight to work at their full capacity. Make sure there are no obstacles to the south of the panels. 

Install in an Optimal Angle

Installing panels at an optimal angle is another prerequisite to ensure that you can produce as much electricity as you can. The tilt of the panels can influence their power production, as they should face such an angle of the sky that you get the best possible power production. You need a professional to calculate at what angle you should place your panels. 

Remove Obstructions

Removing obstructions is also important. While you cannot take down buildings to the south of your home, you can take care that the greenery is always trimmed, so it does not cast any shade on your panels. Chimneys and tree trunks can also reduce your solar panel output. 

Use Solar Tracking Systems

While ensuring the direction and the tilt of your solar panels is important for power production, a solar tracking system can ensure that your panels always face the sun. These systems are often too big to be installed on the rooftop, while they can be easily installed on land and in large-scale systems. 

FAQs

Can you Run Solar Panel Straight to Battery?

You should never run your solar panel straight to the battery. Although solar panels produce DC (Direct Current), you need to install a solar charge controller. This way, you will be sure that there is a device that can offset any fluctuations in the voltage coming from your solar panels and protect your battery. 

At what Temperature do Solar Panels Stop Working?

Your solar panels have a peak-temperature spot – a sweet spot for producing electricity. Although they need very high temperatures to actually stop working, solar panels actually start losing their efficiency when they reach temperatures above 77ºF. This is the reason you will see that solar panels work the best in direct sunlight during the colder part of the year. 

How do I Winterize my Solar System?

There is not much that you should do to winterize your solar panels. Generally, you will need to remove any leaves or other debris from the panels, clean them (can be done with a hose from the ground level), and call a professional to inspect the panels, the inverter, the solar charge controller, and the solar battery, if you have one. 

Why do Solar Panels not Work on Cloudy Days?

Solar panels can still work on cloudy days, although with reduced efficiency. The voltage you get here is very low, to the point that you may not be able to power any device or appliance with it. The thing is that solar panels work with direct, rather than indirect sunlight. Nevertheless, your solar panels produce electricity even if there is an occasional cloudy day. 

Conclusion

With as little as four peak sun hours a day, you can convert enough solar radiation into DC electricity that your inverter will convert to AC and send to your home. Although solar panels work best in direct solar energy exposure, your system output can be increased by following our tips on optimizing power production. Furthermore, depending on how much sunlight you get and how much shading there is, you can obtain more usable electricity by installing an appropriate type of inverter. 

Updated on