Solar
Pollution
The world's climate is changing. Experts predict that global warming will
lead to extreme and severe weather patterns unless steps are taken to reduce
our reliance on fossil fuels. Carbon dioxide is one of the most significant
'greenhouse gases' created by burning fossil fuels for energy. Following the
World Climate Change Summits in Rio and Kyoto
the UK government is committed to reducing carbon dioxide emissions in the coming
years. However, the UK's demand for energy is predicted to rise creating more greenhouse gases from
conventional energy production.
Renewable energy
Part of the solution to the increasing demand for energy lies in the
government's promise to generate 10% of its electricity needs from renewable
energy. Renewable energy technologies include wind power, wave and tidal
power, hydro power, wood and biomass fuels that are 'carbon neutral' and
solar energy collectors. Solar energy is easily the most abundant of these
energies on earth and is non-polluting.
Electricity can be generated by photo-voltaic solar collectors although the
cost of this technology is not yet within the budget of the general public.
Solar water heating is perhaps the most affordable active solar technology
for domestic use. Many people still believe that solar energy in the UK will not
work. In fact, parts of the UK receive the equivalent of 60% of the annual solar energy that falls at the
equator! In the absence of direct sunlight solar collectors will absorb
useful energy from diffuse sunlight - such as the daylight on a cloudy day.
Solar Water Heating
Solar water heating offers regular cost savings on fuel bills and compares
favourably with other home improvements. There are several key factors that
influence the time it takes to recover the cost of your initial investment.
The amount of money saved depends on
1. The size and design of the solar heating system
2. The pattern of hot water use
3. The type of heating fuel 'displaced' by solar
A typical system
1. Provides up to 65% of annual hot water requirements
2. Has a working life in excess of 20 years
3. Is free from the regular price increases of electricity, gas, oil, etc.
Converting sunshine to hot water
Solar collectors mounted on a roof are connected to pipes containing a
heating fluid mixture of water and antifreeze. When the sun heats up the
solar collectors, the hot fluid is pumped through the pipes to a heat exchange
coil in the new solar hot water cylinder. Here the captured solar energy is
transferred from the hot fluid in the coil to the household's hot water
supply. The hot water in the cylinder is connected to the taps, shower, washing
machine, etc in the usual way.
In order for the solar water heating system to run safely and efficiently, a
range of valves are installed in the heating fluid circuit. A series of
temperature sensors are connected to a digital solar controller to switch the
system on or off according to the solar energy available.
On days of limited sunlight, solar energy alone may not be sufficient to heat
the household's water to a usable temperature. In this case your conventional
boiler or your immersion heater (if fitted) can be used to further boost the
temperature of the solar heated water.
Hot Water Storage Cylinder
The size of the hot water storage cylinder is generally determined by the
amount of hot water your household uses in a day.
Typical daily hot water usage:
| Appliance | Volume (litres) |
|---|---|
|
Standard sized bath |
60 |
|
Corner bath |
120 |
|
Shower / Power Shower |
15-60 |
|
Washing machine |
50 |
|
Kitchen sink |
15 |
|
Bathroom washbasin |
5 |
A new solar hot water storage cylinder is usually fitted in the airing
cupboard replacing your existing storage cylinder. If the space around your
existing storage cylinder is limited an alternative position or design can
normally be agreed.
Size and quantity of solar collectors
Allow around one square metre of collector surface area for every 45 - 50
litres of hot water to be stored.
Position of solar collector
Collectors in the UK work best when facing south and at an angle of around 35 degrees from the horizontal.
Durability
A well designed and constructed solar water heating system should provide
many years of good service with little maintenance.
Cost
Assuming a life span in excess of 20 years, solar water heating offers good
value for money when comparing the initial investment to the cost of a
household's current heating fuels. The costs of conventional heating may
increase over the years as existing oil and gas supplies diminish and
'pollution taxes' are levied. It is also important to consider the cost of
electricity to run the solar heating system (pump, controls etc). For a
typical home this is less than £5 per year. Solar water heating
cannot be considered good value if the initial system cost is too expensive.
For this reason it is important to shop around for a competitively priced
system using high quality components