How do Vacuum Tubes Collectors Work?

How do Vacuum Tubes Collectors Work?

How do Vacuum Tubes Solar Collectors Work?

This Blog is about basic information on how this type of Solar Panels Collect, Store and Divert  hydronic heat to the indoor areas. The video talks about essential elements of a solar hot  water heating technology...

Do you know that our SRCC Certified Vacuum Tubes Solar Water Collectors are used in Net Zero Energy Homes and Passive Houses?

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Our Technical Team will design your solar water heating system for you. Preliminary Design is always free.

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Do you live in Canada or the northern part of the US? Our Solar Collectors are among the most efficient in Nordic winters! They Generate 1/3 of their Annual Energy in Winter.

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Do you know that our Flexible Stainless Steel Pipes are among the easiest, fastest and safest to install for a solar water heating system?

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Are aware of the Rules of Thumb for sizing your solar domestic water heater?

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Introduction to Evacuated Tube Collector

The Evacuated or Vacuum tubes collector consists of a number of rows of parallel transparent glass tubes connected to a header pipe and where the heat transfer fluid (usually 50% Propylene Glycol) circulates and absorb heat generated by tubes. These glass tubes are cylindrical in shape. Therefore, the angle of the sunlight is always perpendicular to the heat absorbing tubes which enables these collectors to perform well even when sunlight is low such as when it is early in the morning or late in the afternoon, or when shaded by clouds.
Evacuated tube collectors are particularly useful in areas with cold, cloudy wintry weathers (most of Canada and the northern part of the US).

So how do Solar Vacuum Tube Collectors work?

Evacuated tube collectors are made up of a single or multiple rows of parallel, transparent glass tubes supported on a frame. Each individual tube varies in diameter from between 1" (25mm) to 3" (75mm) and between 5′ (1500mm) to 8′ (2400mm) in length depending upon the manufacturer. Each tube consists of a thick glass outer tube and a thinner glass inner tube, (called a “twin-glass tube”) or a “thermos-flask tube” which is covered with a special coating that absorbs solar energy but inhibits heat loss. The tubes are made of borosilicate or soda lime glass, which is strong, resistant to high temperatures and has a high transmittance for solar irradiation.

Vacuum Tube Header

Inside the each glass tube, a flat or curved aluminium or copper fin is attached to a metal heat pipe running through the inner tube. The fin is covered with a selective coating that transfers heat to the fluid that is circulating through the pipe. This sealed copper heat pipe transfers the solar heat via convection of its internal heat transfer fluid to a “hot bulb” that indirectly heats a copper manifold within the header tank.

Vacuum Tube Header Main

These copper pipes are all connected to a common manifold which is then connected to a storage tank, thus heating the hot water during the day. The hot water can then be used at night or the next day due to the insulating properties of the tank.

The insulation properties of the vacuum are so good that while the inner tube may be as high as 150oC, the outer tube is cooler to touch. This means that evacuated tube water heaters can perform well and can heat water to fairly high temperatures even in cold weather when flat plate collectors perform poorly due to heat loss.

However, the downside is that they can be a lot more expensive compared to standard flat plate collectors. Evacuated tube solar collectors are well suited to commercial and industrial hot water heating applications and can be an effective alternative to flat plate collectors for domestic space heating, especially in areas where it is often cloudy.

Evacuated tube collectors are overall more modern and more efficient compared to the standard flat plate collectors as they can extract the heat out of the air on a humid, dull overcast days and do not need direct sunlight to operate. Due to the vacuum inside the glass tube, the total efficiency in all areas is higher and there is a better performance even when the sun is not at an optimum angle. For these types of solar hot water panels, the configuration of the vacuum tube is what’s really important. There are a few different vacuum tube configurations, single wall tube, double wall tube, direct flow or heat pipe, and these differences can determine how the fluid is circulated around the solar hot water panel.

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10 comments

  • tony

    Helo, we are the largest solar vacuum tube production base in China.
    Welcome to contact us.
    Tony@suntyeco.com
    www.suntyeco.com

    http://suntyeco.blogspot.com/2018/09/sunty-eco-solar-vacuum-tube-heat-pipe.html

  • Technical Team Member

    Hello Rico Spence. The estimated lifetime of a Vacuum Tube Solar Collector is 20 Years. Yes you might need to change tubes a couple of years of installation. Tubes do sell on our website separately.

  • Technical Team Member

    Hello Leighton Hester. There are 2 ways to estimate the possible savings: Either refer to our Blog (https://hydrosolar.ca/blogs/news/how-much-energy-can-your-hydronic-solar-system-generate) or simply fill out this form (https://hydrosolar.ca/pages/solar-domestic-water-heater-sizing-request) and our technical team will calculate savings for you based on your location and heating behaviour.

  • Leighton Hester

    How do I estimate the cost and possible savings from using a solar vacuum tube collector? I want to make sure my investment is saving me money in the long run. I live in a cold, wintry part of the United States and suspect these are the solution for me, but I want to be sure.

  • Rico Spence

    How long do these tube solar collectors last? I’m curious as to whether the tubes every need to be replaced and whether there is any regular maintenance involved. There does not seem to be from this article. It would be nice to set something up and sort of be able to forget about it.

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