solar collectors
navitron
affordable alternative energy solutions
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EVACUATED TUBE SOLAR HOT WATER PANEL (20 tube) These top-of-the-range solar panel heat collectors are suitable for
heating domestic hot water, swimming pools etc - even in the
winter! One unit is adequate for an
average household (3-4people), and it is modular, so
you can add more if required. A single panel is
sufficient for a 200litre cylinder, but you can fit
2 or more for high water usage, or for heating
swimming pools or
underfloor heating.
Some types of renewable energy are only available in
certain locations, however free solar heating is
potentially available to almost every house in the
UK! Every house should have one -really! And with an
overall efficiency of almost 80%, they are much more
efficient than electric photovoltaic solar panels
(efficiency of 7-15%). And if we compare them on a
like-for-like basis, the price of a Navitron Solar
Water Heater is around 30p/watt (compared to
£6+/watt for solar photovoltaics!) An assembled Navitron 20 tube standard panel and 10 tube high efficiency panel The picture below shows a more basic design - which is commonly employed in hot countries such as Turkey, Greece, Mediterranean, Africa etc. This type of system does not employ heatpipes; instead the water fills the tubes, which in turn heat the header tank (which can vary between 85 and 220litres) by convection. This system is far more basic, but has obvious advantages: no requirement for electric power, no controller, pipe insulation etc required and is very low-cost. However, it is less functional, too large to appear roof-integrated, cannot accept pressure system kits, cannot be used with a standard domestic hot water tank.
FREE DIY INSTALLATION MANUAL (CLICK HERE!!) - 1.9MB (this will take a few minutes to download, so not recommended for dial-up users). This manual covers background information, specifications of the panel, sample plumbing plans and assembly information.
The vacuum tube solar panel has been around for over 10years, and has proved to be reliable and dependable. The vacuum tubes consist of a double wall glass tube (made from strong borosilicate glass ie pyrex) with a space in the centre which contains the heat pipe. The sun's radiation is absorbed by the selective coating on the inner glass surface, but prevented from re-radiating by the silvered innermost lining. This is in effect like a one-way mirror which has been optimised for infra-red radiation. In fact it is very efficient, of the sun light's energy hitting the tube's surface, 93% is absorbed, whereas only 7% is lost through reflection and re-emission. The presence of the vacuum wall prevents any losses by conduction or convection - just like a thermos flask. Because of this, the system will work even in very low temperatures, unlike traditional flat plate collectors. This is why our system can be used to heat up water at the South Pole Antarctic Science Base - where ambient air temperatures can drop below -40°C 
The heat transferred to the tip of the heat pipe is in turn transferred to a copper manifold in which water circulates to heat the domestic hot water tank. If a tube is placed in direct sunlight on a summer day, the tip temperature can reach 250°C - so the system easily heats domestic hot water cylinders to 60°C even in cooler weather! The manifold is heavily insulated with a 2" thickness of pre-formed rockwool to keep the heat in. Unlike flat plates, these headers are so well insulated that they should not require antifreeze in normal operation - the temperature of the header is unlikely to fall below 10°C even in very cold weather. The more advanced solar controllers include a low-temperature facility- should the temperature of the collector fall below a defined level, the pump will operate to allow the the water at the bottom of the tank to heat the collector slightly. In normal conditions, this would never be necessary - but it acts as a good safety margin. How Much Heat Will I Gain? Average Daily Irradiation (Insolation) Figures for Each Month of the Year: (Solar energy reaching each 1m2 of the earth’s surface at UK latitudes)
How Do I Connect the Panel?
Pressurised Systems. The drawing above is one example of how to connect the panel. This is a typical installation that would be carried out by a professional installer, utilising a twin coil solar cylinder. These cylinders are far superior to a standard domestic hot water cylinder - and we can supply these up to around 1300litres capacity! Typical solar cylinders are 175 - 260litres. The additional water capacity allows the user to store heat for several days, to even out variations in day-to-day insolation, although larger cylinders require bigger solar arrays - so we recommend sizing the cylinder to your requirements rather than over-sizing. Typically, we would recommend sizing approximately 30-50% larger than your existing cylinder, assuming your existing cylinder is correctly sized. Most households fit solar cylinders of 135 - 175litres capacity. The solar loop in the schematic above is pressurised -this is almost universal for various reasons:
Most pressurised systems are pressurised using the mains water pressure. However, it is recommended that solar systems are filled with propylene glycol antifreeze (do not use the cheaper methanol-based or ethylene glycol based antifreeze). Navitron supplies suitable antifreeze, and can advise on quantity. Filling with antifreeze requires some method of filling - Navitron has developed a very low-cost method for fillng the system, and these may be purchased along with your solar kit.
It depends on your application and
the method you employ, and a lot of customers take
the opportunity to update their existing hot water
system at the same time. There are many ways to
install solar, and the schematic above is just one
illustration. A really low cost method would be to
install the panel lower than the cylinder, in which
case it can operate on a thermo-siphon basis (convection or 'gravity
feed'). The panel, being mounted lower than the
hot water cylinder, begins to warm when the sun shines,
causing the hot
water to rise, which displaces the cooler water,
thus returning to the panel. This system requires no
additional energy input, no control system and is
self-regulating, simple, cheap and effective - but
not very convenient for most situations, and not as
efficient. In this
case, you will only require the header tank or
pressurised system kit plus copper tube and
insulation. Items you will need to source locally:
What about Swimming Pools?
Installation is very simple. If you have chlorine you will need to fit a stainless steel heat exchanger (this is because chlorine causes copper to corrode). These are available from pool suppliers (they are needed for conventional heating methods for the same reason). If you dont have chlorine, you can simply put the solar panel in-line with the pool filter, so that the pump directs water through the panel before returning it to the pool. As the panel will NOT radiate heat on cold days, heat losses will be confined to your pipe runs only - so you do not necessarily need a controller, although one can be fitted, to control a 3-way solenoid valve to divert the water through the panel when the panel is hotter than the pool water.
A Word on Flat Plates Navitron does not recommend flat plates for the UK. However, there are some customers that insist on flat plate panels, usually for aesthetic reasons. If this is the case, you can fit a Navitron selective-coating flat plate panel. These are not as efficient as vacuum tube panels - so their output will suffer in cold, overcast or windy weather - but with the selective absorption coating, the Navitron panels are as good as the best flat plates on the market. Flat plate collectors only provide a useful amount of heat during the summer months in the UK. due to their high heat losses during cold or windy weather. When the ambient temperature drops, the heat loss can easily exceed the heat gain - turning your flat plate solar collector into a radiator! The reason for the popularity of flat plate collectors is their cheap construction - you can build one yourself for a few pounds worth of scrap material, or you can buy one for £300-500. Once upon a time, flat plate panel prices were a lot cheaper than evacuated tube panels, which typically cost £800-1200.......Navitron has changed all this! Vacuum tube collectors will provide useful heat for 12months of the year, as long as the sun is shining, and can even produce heat in overcast weather. In April, an overcast day without any sunshine is still able to heat a 210litre hot water cylinder to 40°C with Navitron vacuum tubes. A sunny day in April will warm the cylinder as high as 60C using Navitron panels! A Word on Plastic Pipework There are some flat plate systems
for sale in the UK, such as the Solar Twin system,
which use plastic, silicone or rubber pipework,
which makes installations
easier and to reduce costs. Whereas this pipework
may be ideal for their system (a flat plate panel), it is definitely not
adequate for evacuated tubes. On a hot sunny day,
such panels will will self-regulate to around 60C. Evacuated tube systems are capable of heating
the water beyond 140°C. Most plastic pipework has a
working temperature of no more than 65°C, and is
able to stand no more than 90°C - so you should
always use copper or stainless steel pipework for solar installations. A word
about Navitron prices Navitron was set up to sell renewable energy systems because we did not feel that the high prices charged in the UK for renewable energy were ethical ( 'If you care about the environment, then you can dig deep in your wallet' they seemed to be saying). We set about selling at fair prices, and as anticpated, the market price for solar, wind etc has dropped signficantly since we started. We still maintain the keenest prices in the industry, but at the same time, we are able to provide good technical support, and we always try to provide free help and advice where possible. A WORD ABOUT MY COMPETITORS: Some of our competitors are very uneasy about our prices. The extent of their profit margins becomes quite obvious when there are companies such as Navitron with fair pricing structures in the market. We prefer to work with our competitors, rather than against them, to help promote renewable energy in the UK and Europe, but others do not necessarily feel the same way. It is therefore no surprise that one of our competitors has made legal threats about our pricing and marketing techniques. Maybe we should publicly name and shame this competitor?! TRADE ENQUIRIES WELCOMED! We are building a network of distributors across the UK, Ireland, and Europe. This is quite important for us, as it is difficult to transport a single box of tubes by courier (as they all seem to throw parcels around). However, we can transport larger quantities with much less trouble. The cost of packaging and shipping delicate items is considerable, hence the benefit of having local distributors both inside the UK and within Europe. We are currently looking for potential distributors in Canada and the USA. Navitron panels are already sold throughout most of Europe, so if you are outside the UK, please contact us for details of our distributors in your country. Brand Names:
Solar water heater converts solar energy into thermal energy, then heat the water step by step. The beauty of this system is it does not create pollution or harmful emissions, and is extremely economical - the fuel (sunshine) is free! Plus, they are environmentally friendly. To take full advantage of these heaters, you should ideally have an unshaded, south-facing location (a roof, for example) on your property, although they can be utilised at ground level also. This type of Solar water heater is now extremely popular in many areas of the world, are are now becoming much more popular in the UK, due to their high efficiency. Until now, solar panels were not particularly popular in the UK due to their low efficiencies during the spring, autumn and winter months. Classic solar panels (flat plate collectors) work equally well as radiators - and therefore unless ambient temperature is high, heat losses are considerable. Flat plate collectors, despite their poor performance at UK lattitudes, have remained the panel of choice until now, due to their low cost, and DIY-suitability. However, we are now able to offer much higher efficiency vacuum tube collectors at similar prices to flat plate collectors. CLICK HERE - to Download our Comprehensive Information Pack
click here for our full price list
Email: sales@ navitron. org. uk |
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Swimming
pools are an ideal application for solar water
heating, as the temperature required is quite low -
under 30°C. Most installers will recommend flat
plates to keep the price down - because the amount
of panels required is much larger than for heating
domestic hot water - however, if you can buy a high
efficiency evacuated tube solar panel for the same
money - you might as well enjoy solar heated pool
water for a greater proportion of the year - instead of just in July and
August! If you used flat plates, a rule of thumb for
calculating what you need is to fit the equivalent
of 50% of the pool's surface area. For Vacuum tube
panels, this is reduced to 25%-35% (depending on
type of pool, level of insulation, pool covers,
indoor/outdoor, above/below ground level etc)- and of course, they
will carry on working in the autumn, winter and
spring. The Navitron panel is 2.25m2 so
(working on the 25% coverage figure) each panel will heat 11m2 of pool area. A
40m2 pool would only need 4 Navitron
panels. Compare this to the cost of heating a pool
for a year! Large pool installations can pay for
themselves in under 18months!
Solar
energy is the cleanest and most inexhaustible of all known
energy sources. Solar radiation is the heat, light and other
radiant energy that is emitted from the sun. The sun's energy,
although plentiful, has been hard to directly harness until
recently. 