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Be a Karen – not a Dick or a Dylan...


do your research

Karen did her research and got 70% more daylight with a Solarspot*


Typical Solartube customer

Dick spent more money and bought a Solatube but got 40% less daylight*


Dylan bought a Velux flexible sun tunnel – lucky he has a good torch*

Up to 70% brighter than the next best system*

Unless you have the opportunity to see them side-by-side it’s difficult to visualise the difference between one sun tube and the next. So to help illustrate this we’ve made a very simple comparison to domestic light bulbs.

If you consider the Solarspot D-38 to be a 100w electric light bulb (on a bright day it would be significantly brighter), the ‘next-best’ sun tube system would be the Solatube 290DS or Solarspot D-25 would be 60w bulbs.

Solarspot 70 percent brighter than the next best system

*350 – 400mm sector.

The Science Behind the Solarspot

What makes Solarspot the brightest choice – we are the only manufacturer that publishes independent comparative test data that allows you to be able to see just how see how our system compares to the likes of Solatube, Sunpipe or Velux. So when we say that we’re brighter you know that it’s true. All of our testing is carried out but world renowned authorities; the BRE (Building Research Establishment) in the UK and CSTB in France.

Unlike virtually any other product a solar tube has only one function, to bring in daylight from the outside to the inside, yet most suppliers seem to offer confused information making it difficult for the customer to determine which manufacturer supplies the product that provides the most light.

The test results provided by Solarspot make it clear how a Solarspot compares to the so-called ‘leading systems’ on the market.

We tested the lead products in the 350 – 450mm category as it’s probably the most specified system size. For this comparison three 2.2m systems where passed over to the BRE for testing.

The systems sent were the:

  • Monodraught SunPipe 450
  • Solatube 290-DS
  • and our own Solarspot D-38.

All three units were tested in over-cast light, the scenario recommended by the BRE as it provides a level playing field so that most accurate indication of the products performance can be measured.

The BRE were then able to produce an efficiency figure for each of the system so that calculations could then be done to determine just how much light each unit will deliver (compared to another) regardless of external conditions, tube length etc. The Solarspot D-38 significantly out-performs the other two being 33% more efficient than the SunPipe and 44% more efficient than the Solatube.

Whilst the Solarspot D-38 is an impressive 44% more efficient than the Solatube 290-DS, it actually delivers around 70% more daylight. This is due to the slightly wider tube diameter of the Solarspot.

Probably the best selling product in this size category is the Velux 350mm flexible system. Using the same testing process, the Velux flexible unit was shown to have a meagre efficiency level of less than 4%. Compare this to the Solarspot D-38 with an efficiency of 57%, and a slightly wider diameter, and you would expect to get roughly 2000% (20 times) more light than the Velux.

Decomposition of light rays in flexible sun tube systems

Decomposition of light rays in flexible sun tube systems

The same is true for all of the systems, whatever the size or configuration (bends etc.), efficiency is king. Take the 250-300mm category as an example; the CSTB in France tested the Solarspot D-25 and Solatube’s 160 DS and return figures of 55% and 35% respectively. Then factor in that the Solarspot averages a diameter of 260mm compared to the Solatube at 237mm and the D-25 will deliver roughly 70% more light. In fact this level of efficiency allows it to deliver the same light levels as the larger Solatube 290-DS.

At the other end of the scale if you compare the Solarspot D-65 (650mm diameter) with the larger Solatube M74 (740mm diameter) and the extra performance of the D-65 allows it to deliver around 10% more light.

Whilst this is important to consider when fitting single units it’s vital when working on larger projects with multiple units. Take an office situation with 80 Solatube 290-DS units specified; by switching to the Solarspot D-38 it would be possible to reduce the number of units by 40%, greatly reducing the cost in both materials and labour, just replacing like-for-like and getting a massive 70% more light for better year-round performance.

BRE independent testing

Solarspot D-38 out-performs the competition

Read the BRE Test Report

Before buying or specifying any solar tube system ask to see an independent appraisal of the product’s efficiency figure. For technical information and full test report contact us at

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