Sarnian Roofing to offer Solar UK hot water collectors and PV panels in Guernsey

July 13th, 2010 by Richard Lord

Solar UK has teamed up with Sarnian Roofing Ltd. to offer solar thermal (solar water heating) systems and photovoltaic panels to the Guernsey market.

Geoff Fox of Solar UK gave a presentation about his company’s products on 9 June 2010 at The Venue of the Fermain Valley Hotel.

Solar UK manufactures solar thermal systems in the UK and sells USA-made photovoltaic panels.

Mr. Fox said that his company’s solar thermal evacuated tubes can achieve a 93% energy efficiency and photovoltaic panels can achieve a 17 % efficiency.

On the day of his presentation it was overcast and the air temperature was 20 degrees Celsius.  Mr. Fox had a Solar UK evacuated tube lying outside.   Even on an overcast day the internal temperature recorded by the thermometer inserted into the evacuated tube reached 150 degrees Celsius.

Jan Van Deneeckhaut of Renolit and Geoff Fox of Solar UK hold a sample panel of evacuated tubes in the grounds of Fermain Valley hotel. (click image to expand)

Mr. Fox recommended evacuated tube collectors over flat plate collectors for heating water.  Although evacuated tubes are more expensive than flat plate collectors, they are more efficient at absorbing solar radiation during the winter months.

Because flat plate collectors are less efficient during the winter, larger flat plate collectors are installed, and these tend to be over-sized for the summer months when they collect more solar radiation than required.

Flat plate collectors reach the efficiency of evacuated tube collectors only during the height of the summer .

Mr. Fox said that 60 degrees Celsius was the target temperature for a hot water tank.  An optimum-sized LaZer2 solar water heating system should be able to provide between 50 and 70 percent of the annual domestic hot water requirement, and up to 100 percent of the hot water requirement during the summer months.

Mr. Fox provided some rules of thumb for sizing panels of solar thermal evacuated tube collectors.  A one metre square collector was sufficient to heat 50 litres of water.  The LaZer2 collector manufactured by Solar UK has a physical size (aperture) of 1.0 square metre.  For a standard house, two square metres of solar collectors are installed with a 180 litre cylinder.

Mr. Fox said that Solar UK LaZer2 collectors are designed for the UK climate. They work well at British latitudes even in mid-winter when the sun is only 26 degrees above the horizon.  They absorb 12 percent more energy since they are horizontal tubes.  The cylindrical evacuated tubes absorb light from low as well as high elevations.

The evacuated tubes are made of Pyrex, and they are very strong.  Pyrex is much smoother than window glass.  Dew forming on the tubes at night is sufficient to clean them.

Solar UK have teamed up with Renolit, which produce Alkorbright.  Alkorbright is a highly reflective white PVC roofing membrane that minimises dirt sticking to it, retains its white colour, and is cleaned by rain.  Its reflective surface increases the efficiency of the solar thermal panels by nine percent.

Geoff Fox provided some rules of thumb for the installation of photovoltaic panels.  He said that 8 square metres of PV panels could generate about one kilowatt.  A one kilowatt system at Guernsey’s latitude could provide about 950 KWh per year.  This amount of panels would weigh about 100 kilograms and would cost about £7000 to install.  It would save about 500 kilograms of C02 emissions per year.

PV panels produce direct current (DC) , which needs to be converted to alternating current (AC) with an inverter.  A series of photovoltaic panels could produce enough DC to kill a person.  Mr. Fox said that for commercial buildings, multiple inverters were more reliable than one big inverter.

He predicted that solar thermal collectors (solar hot water panels) would become much more prevalent as the cost of heating water increases.  Heating hot water represents about 45% of a home’s energy bill, he said.  He predicted that there would be an energy shortage in the UK.   He said that more companies would be involved in the distribution and sales of solar thermal systems but the knowledge of these systems would not be of a uniformly high level.  Mr. Fox recommended dealing with companies that are part of the Solar Trade Association.

Mr. Carl Armitage, Contracts Manager for Sarnian Roofing Ltd., advised that anyone considering the installation of solar thermal systems or photovoltaic systems on their roof should make certain their roof is sound before commencing the work.  Solar UK solar panels have a 25 year warranty.   The roof should last at least this long.

Mr. Fox provided his 5 mb PowerPoint Presentation for download.  Mr. Fox can be contacted by phone on 01892 52 63 68 or by email:  Geoff.Fox (at) solarUK.com

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