Solar Hot Water Systems
Why Solar water heating?
Reduce your fuel bills by utilizing free energy from the sun. Why waste the suns energy when it is in such abundance?
With rising fuel prices and security of energy supplies being diminished its time to become more energy independent as individuals householders and businesses.
A solar water heating system will reduce your fuel bills by
pre-heating hot water for baths, showers and swimming pools for use all year round. On sunny days during the summer it may provide all of your hot water needs. Any increase in temperature in the water supply to your boiler will reduce the energy used to heat water to the desired temperature. 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 vacuum tubes. A sunny day in April will warm the cylinder as high as 60C using vacuum tube panels!
A survey will be required due to the individual nature of each building installation and customer requirements.
How do they work?
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 i.e. 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 that has been optimised for infrared radiation. In fact it is very efficient.
Of the sunlight'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.
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 summers 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 rock wool 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 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.
Average Daily Irradiation (Insolation) Figures for Each Month of the Year
(Solar energy reaching each 1m2 of the earth’s surface at UK latitudes)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
| MJ/m2 day | 2.3 | 4.2 | 7.0 | 11.6 | 15.0 | 18.0 | 16.0 | 13.0 | 10.0 | 6.0 | 2.8 | 1.7 |
| kWh/day per m2 | 0.64 | 1.17 | 1.94 | 3.22 | 4.17 | 5.00 | 4.44 | 3.61 | 2.78 | 1.67 | 0.78 | 0.47 |
| Heat Gain from 1 Navitron panel per day (k Wh) | 1.15 | 2.11 | 3.49 | 5.80 | 7.51 | 9.00 | 7.99 | 6.50 | 5.00 | 3.01 | 1.41 | 0.85 |
Installation
Installation in most cases can be carried out in 2 days for an average sized semi although this can be established with an initial survey.
Typical prices of systems can be found on our prices page. A basic 20-tube system will cost in the region of £2500 including solar cylinders up to 172 litres that will supply hot water for an average 3-bed semi. The prices and sizes are meant as a guide as individual properties, customer requirements and hot water needs can vary.
Planning
Current planning guidelines in the Lancaster and Craven Districts are such that no planning is required as long as the collector or any part does not protrude from the natural pitch of the roof by more than 6inches or 150mm. Our Navitron collectors only protrude about 130mm. Planning issues will need to be confirmed with your local authority if your property is a listed building or you are in an AONB (Area Of National Beauty) or conservation area.
Is my house suitable?
Most roofs are suitable for solar thermal installation. The perfect location would be on a south facing roof plane for optimum performance. They can also be mounted on southeastern or southwestern facing roofs with only a slight reduction in performance. If this is not available there are other options. The Navitron collector can be mounted on a vertical wall or on a flat roof with the use of a flat roof mounting kit. It might be that the best place is on a gable end or a flat roof or lean too. They can also be mounted in your garden but in all cases they need to be fitted as close to your hot water cylinder as possible to reduce any losses in heat energy over the length of the pipe run.
It is recommended that before you consider a solar thermal system you should ensure that your house is suitably insulated and that you have eliminated draughts as best possible.
£ Pricing
Solar hot water systems can vary substantially from house to house, user to user and so a survey is necessary to establish the system requirements and ultimately the price. The variations can be such things as quantity of water used and required, location and suitability of installation, current boiler type and requirements of the system. Installation prices can also vary depending on the access, size of system and also customer’s requirements of that system.
For this reason we can only give a guide price of £2500 which is for an average sized 3 bedroom semi and allows for a cylinder up to 172 litres. DIY kits are available from £1900.
Please call or email to arrange a free survey.
