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Solar Tubes: All You Need to Know

How do you get natural sunlight into a basement? With solar tubes! The basement is just an example of one of many interior spaces that can be lit up using solar tubes. Skylights can do the same thing too, but they are slightly different when it comes to solar tubes.

In this article, we take a look at all the aspects of solar tubes, and how they compare with skylights.

What is a solar tube?

The solar tube is also known as the sun tube, light tube, sun tunnel, tubular skylight and daylight pipe. It looks exactly like a tube, thus its name. The solar tube mentioned here is not to be confused with thin-film agri voltaic solar tubes and photovoltaic solar tubes which are mainly made for generating electricity.

source: Wikipedia

A solar tube is made from metal. The end of the tube that receives sunlight is called the dome and it is made from a translucent, weather-resistant material. The other end is covered by a diffuser, which dissipates sunlight into the interior space.

The inside of the solar tube is lined with a super-reflective coating which amplifies sunlight as it travels through to the other end of the tube.

Its function is similar to that of a skylight, which is to allow natural light through a roof into an interior space, such as basements, dark corridors and bathrooms.  The space can be immediately under a roof or even a few floors below.

As solar tubes are relatively small, they can be slotted between roof rafters without compromising the structural integrity of the roof. Many people have used solar tubes to permanently light interiors, helping to save on their electricity bill during the day.

The solar tube is often sold with accompanying parts which help to fit it on different types of roofs.

Types of solar tubes

1. Simple solar tubes

Broadly speaking, there are two types: rigid and flexible. The rigid type is straight. The flexible type is either bent or curved. 

A rigid solar tube gives off more light than a flexible one because it offers a straight path for sunlight down to the end of the tube. This makes the rigid solar tube better for longer distances. The flexible type is more suitable for short distances and flat roofs.

Another factor to take into account when deciding which type of solar tube is suitable for you is the type of roof. Most products out there are for roofs made from asphalt. If your roof is made from tile or metal, you’ll need adapter parts which usually come with the solar tube.

2. Adjustable solar tubes

These are the 2.0 versions of the simple rigid and flexible types. They come with adjustable lenses or daylight dimmers which you can control to cover the solar tube. It is useful when you want to stop sunlight or reduce the intensity of sunlight entering the solar tube.

3. Photovoltaic-integrated solar tubes

The photovoltaic-integrated solar tubes are the newest type. It is a hybrid with different additional features: 

  • Pv-integrated
  • Pv-integrated with fan

Photovoltaic or solar cells are integrated in this type of solar tube, allowing you to generate electricity while sunlight streams through the tube. Some models come with an in-tube bulb which you can dim as and when you wish.

The Skylight-Powered Exhaust and Ventilation Fan for the Sky Tunnel XL2 is an example of a pv-integrated solar tube with fan. It is offered as an accessory which can be fitted into the solar tube. The ventilation fan runs off a motor powered by sunlight in the solar tube.

Solar tube sizes

Solar tube sizes are determined by the diameter of the tube. Sizes vary from as small as 2 inches to 48 inches, depending on brand, type and use (residential or commercial). It is said that a 10-inch tube is comparable to three 100 watt bulbs. There is no limit to the length and can be as long as they need to be.

Do solar tubes really work?

Yes. On a bright day, a 10-inch solar tube can give you about the same amount of light as three 100-watt bulbs, enough to illuminate a 200 sq. ft. room well.

Do solar tubes work at night?

Yes, if you choose the right type. If you need light at night for this space, go for a solar tube model that includes a light bulb. 

Benefits of solar tubes vs skylights

You can’t expect solar tubes to be as bright as skylights. Solar tubes and skylights may serve the same function, but they have slightly different strengths.

  1. Solar tubes have better reach

The design and nature of skylights don’t allow them to penetrate through floors. In contrast, solar tubes can direct daylight at an angle through multiple layers in a building. That is why solar tubes can even light up a basement.

  1. Solar tubes have more design flexibility

Skylights are typically squarish and hard to miss when you walk into a room. In contrast, solar tubes can come in a wide array of permutations in design. They can also be discreet and be fitted into narrow or small spaces.

  1. Lower risk of leaks for solar tubes

Skylights are known for their tendency to leak due to water and debris pooling in them. Solar tubes, on the other hand, are less likely to leak because of their size and design.

  1. Solar tubes and skylights have positive health effects

Populations in temperate countries where the sun doesn’t shine as brightly don’t get as much vitamin D as their counterparts in tropical countries. According to the National Institutes of Health, 42% of Americans have a vitamin D deficiency. 

Vitamin D helps to boost your immune system, mood and the health of your bones and muscles. Having natural sunlight pour into the house is useful when you’re stuck inside and can’t go outdoors.

Sunlight streaming directly down into the house through solar tubes and skylights is more effective at bringing vitamin D to you than through windows. However, the intensity of sunlight received through a solar tube is far less than that of a skylight’s.

  1. Lower overall cost of solar tubes

The cost of solar tubes and installation is less than that of skylights. Solar tubes don’t need any changes to the drywall or framing.

  1. Easier installation process for solar tubes

This is because they have a small footprint and can easily be fitted between rafters into a roof. Skylight installation is a more laborious task, needing proper care to ensure roof structure integrity while a large window is embedded into your roofing membrane. 

  1. Solar tubes offer more energy efficiency

During a hot summer, skylights provide more direct sunlight, thus, heating up your home and driving up air conditioning costs. However, indirect light from solar tubes transmits less heat energy, leading to less energy needed for air-conditioning.

Conversely, in winter, heat dissipates less easily through a small solar tube compared with a wider area of space in skylights. You save more money both ways using solar tubes.

  1. Less maintenance for solar tubes

Bird poop and debris collect easily on skylights and it’s hard not to notice them. However, solar tubes have much smaller surface areas and the usually curved dome of their exterior heads make it more difficult for elements to settle on.

What are the drawbacks to solar tube lighting?

  1. 1. No pretty views from solar tubes

Skylights provide a direct view of the sky and stars.

  1. Skylights add resale value

Skylights are an interior design feature that is attractive to many, whereas solar tubes don’t particularly add visual appeal.

  1. Skylights can be opened and closed for ventilation

Solar tubes only let light in but they can’t be opened in any way to let air in.

  1. Limited passive solar heat from solar tubes

Skylights offer passive solar architecture which is beneficial during winters. Solar tubes are simply not big enough to create this greenhouse effect. 

  1. Less effectiveness of solar tubes in certain situations

The longer the tube, the less light they provide. They are most effective at one story depths since the deeper they are, the less light there will be. Furthermore, if your roof is shaded, you might get a weakened light.

  1. Water condensation problem

In humid climates, water condensation may occur in solar tubes, and drying it out becomes a big hassle.

  1. Solar tubes are susceptible to damage in extreme temperatures

The external end of a solar tube can be more easily damaged or cracked than a skylight when it is subjected to extremely hot or cold temperatures.

How to install a solar tube?

Installing a solar tube is less complicated than a skylight if you’re cutting through just one ceiling hole below the roof. Here is a step-by-step guide for DIYers.

How to clean a solar tube?

The dome of a solar tube can get dirty over time. Here is a guide on how to clean the entire tube. Otherwise, you can just clean the solar tube diffuser

Conclusion

Solar tubes have slightly more benefits over skylights if you’re looking for efficiency in cost, maintenance and ease of installation. However, the incorporation of lighting control and photovoltaic technology has produced newer prototypes, making solar tubes more multi-functional. 

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