solar water heating diagram

The most efficient way to use the sun to heat water

With advances in technology solar water heating systems have become incredibly efficient. Evacuated Tube solar water heating offering efficiencies of well over 90%, which means that more than 90% of the sun's energy landing on a surface is converted into heat which can be used to heat water.

Evacuated Tube solar water heating is one of the cheapest renewables, with costs starting from pennies per Watt required, comparing to pounds per Watt for PV Solar and Wind Turbine power generation.

How Evacuated Tubes Work

• Evacuated Tubes are made from glass - typically ultra-strong and heat resistant Borosilicate with a single wall construction.
• Inside each glass tube all air is removed making a vacuum.
• Most of the infra-red radiation (i.e heat) from the sun is absorbed by the special coated absorber material. The Infrared reflecting layer ensures low thermal emission, the metal oxide absorption and anti-reflection layers ensure the highest solar absorption, while offering resistance against outside agents.
• As the Glycol flows through the flow and return of each evacuated tube it is being heated. This hot Glycol is then pumped through pipes to the hot water cylinder with the end result that the water gets hotter and the Glycol cooler. The Glycol then continues its journey around the system back out to the Solarfire to be reheated.
• This simple system is completely sealed and needs minimal maintenance over its life.

The advantage of using evacuated tubes is that they will work even during the coldest winter months.

The vacuum prevents the heat tube from being cooled much by the ambient temperature which can be well below freezing, and so winter sun can easily heat water to 50 degrees even in the depths of the coldest season. Even if it is very cloudy and very cold, enough sunlight gets through to keep the tubes well above freezing and so they will be still pre-heating the water reducing the costs of heating the water.

Why does the Solarfire use Single Walled Tube?

The standard tubes are double-walled, with a vacuum between the two walls of the glass. The centre is filled with air and the heat pipe runs up through the centre. The single walled tube is entirely filled with vacuum, and the vacuum is sealed by a glass-metal bond sealing the Flow & Return pipes in the glass tube. The single walled tube has an advantage over the double-walled tube in that it reacts much quicker to sunlight (e.g. in winter it starts to heat water within 5-10 minutes rather than 10-15 minutes, and in summer the single walled tubes will start heating in just 30-45 seconds whereas the double-walled tubes will take 2-3minutes) - so it is slightly more efficient in marginal conditions. A 12 tube single walled panel (65mm diameter tubes) produces only about 10% less heat than a standard 20 tube double-walled panel (47mm diameter tubes).

You can contact one of our solar energy specialists by calling:

01225 430 360

or by email: info@greenphoenix.co.uk

Alternatively, fill in our Contact Us Form, and one of our team will contact you.


Get Skype and call Green Phoenix for free.