NARVA – vacuum tubes for solar thermal

NARVA – the vacuum tubes for solar thermal! With our products we make sure to have security and power, but more so the german quality! We are a loyal partner and customer from NARVA for many years now, because the company combines in its products everything AKOTEC stands for. Since their founding in 1966, the company worked in this field of industry until it found its specification. The technology from the NARVA solar tubes is unique and patented, so that the company doesn’t loose its unique selling point. The unique glass-to-metal connection, the nano coating and the hail storm resistance of the tubes have been persistent over the years and make sure our customers have high outcomes with their solar plants. Get to know more here!

Who is NARVA

The company started 1966 with light bulbs in Brand-Erbisdorf. Over the years, the company produced fluorescent lamps, tanning lamps and much more. The company got more modern over time and the specification more focused. Today, the company is known for the production of full vacuum tubes in the area of solar thermal and it sells its products to manufacturers of solar collectors like AKOTEC.

What is NARVA doing

NARVA is a competent authority in the areas of glass production, vacuum technology and coating technology. With its awareness of sustainability and the environment, the company entered the solar thermal market in 2005. In 2007, the first full vacuum tube was launched. The success made the company get property rights and patents, because the high-power heat pipes with their high efficiency are unique on the market.

Long-time partner & customer

We are a long-time partner & customer from NARVA. The specification of the company and the manufacturing of the tubes on this level of innovation, has convinced us without doubt. We know the quality and power of the products first hand and stand behind it with 100%. This high identification and the german partner mean security and power for us and our customers. Our satisfied customers and the successfully finished projects can confirm that.

Normal double-walls tubes

A double-walled vacuumized glass cylinder encloses the internal components. Since the end must be closed with a cap due to the design, a constant exchange of air takes place between the interior of the tube and the surroundings. This can lead to heat loss and condensation in the worst case. This water can lead to the destruction of the vitreous during frost. In addition, this exchange with the ambient air leads to corrosion and dirt on the absorber sheet. To avoid these problems, NARVA developed the single-wall tubes.

Our Single-wall NARVA tubes

In the single-wall NARVA full vacuum tubes we use, the inner absorbing part is completely isolated from the environment. The structure is comparable to a light bulb. The inner tube with the absorber is completely in vacuum. Experts speak of full vacuum tubes. These tubes are manufactured by the east-german manufacturer NARVA, a traditional company with many years of experience in the production of light bulbs, where 200,000 fluorescent tubes are produced per day.

The glass-to-metal connection of the vacuum tubes

There were some issues in the past with other manufacturers and the glass-to-metal connection of the vacuum tubes, like leaks and the associated vacuum and heat loss. So far, there were only two kinds of glass-to-metal connections on the market: the compression closure or the classic glass-to-metal connection. In order to avoid the recurring problems, NARVA came up with a solution: the NARVA glass-metal connection. The idea was to avoid the tensile stress on the glass and therefore to prevent breakages. Find out the thoughts behind the tubes here.

Conventional tubes with
vacuum-compression-closure

With this connection, a metal cap is pressed onto the cladding tube with hot air pressure. Lead oxide glass serves as sealing, which melts during this procedure. The particular problems are the three different materials that are interrelated and need to ensure a vacuum seal connection. Especially, if high temperature differences are operating, the connection can lose its vacuum sealing. The closure is robust.

Conventional tubes with
classic glass-to-metal connection

With this method, a tubular edge, which is made of metal (e.g. copper), is pressed axially into the glass tube. The end of the glass tube is heated up until it is soft enough for it. If the connection is not affected by any forces, there are no problems with the vacuum. However, there are affecting forces like wind, which leads to a breaking connection, especially by transverse forces. This leads to vacuum loss.

The solution:
NARVA Glass-to-metal construction

To avoid these problems, NARVA developed a new and very robust glass-to-metal connection. The aim was to obviate the danger of vacuum loss with thermal compression method. This was achieved by creating the metal connection like a barometer box in such a way that no tensile load affects the glass. NARVA puts the glass around the metal cover and melts both together. It is not just glued as many manufacturers do.