What are Solar Water Heating Panels?
Confused about Solar? Many people seem to be a little confused as to how solar panels actually work. This misunderstanding however, is perfectly reasonable and stems from the general acceptance of solar panels on things like calculators or garden lamps. These types of solar panels are called photovoltaic solar panels or PV Solar Panels and we will discuss these in more detail in another article. For now, it is worth explaining about the panels that people are less familiar with but give the greatest opportunity to reduce household fuel costs. These panels are called Solar Water Heating Panels.
Solar Water Heating Panels
Solar Water Heating Panels use the suns radiation to heat water in panels. This panel is connected to your hot water storage tank. When the temperature in your tank is lower than that of the panel on your roof the water is pumped out of the roof panel through a heating coil in your hot water tank. This heats the water in your storage tank. When it is cold and dull outside the pumps leaves the cold water in the roof panel and your storage tank is heating with your conventional boiler. This simple but effective system is typically capable of heating up to 70% of your annual requirement for domestic hot water. Given this fact it is probably the most cost effective and way of installing a renewable energy system in your home.
There are two type of solar collectors/panels commonly used in the UK, flat plate panels and evacuated tube collectors.
Flat Plate Panels vs Evacuated Tube Solar Collectors
Evacuated tube solar collectors are typically more efficient than flat plate collectors. This does not necessarily mean that evacuated tubes can produce more hot water just that the panel area can be reduced. Typically you will find that for a flat plate collector area of 4m2, evacuated tubes need approximately 3m2 for the same size hot water tank. With this in mind, the amount of hot water generated throughout the year will be very similar.
An independent study by the DTI compared a number of different types of system and the panel that produced the most hot water was of the flat plate variety.
The cost of the panels are now fairly similar, but some people believe that flat plate solar collectors are more aesthetically pleasing. However, technically the evacuated tubes have a significantly higher output than flat plate systems when the ambient temperature is low, i.e. in winter.
So in summary, where roof area is an issue evacuated tubes are the best option. Otherwise, you should consider both evacuated tubes and flat plate collectors.
Typically, properly specified solar water heating systems will pay for them selfs in around 10 years.