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Please select a category that your
question relates to:
Installation
Systems
Solar Collectors
Installation
Do I need planning permission to install solar systems?
Planning permission is not normally required; the collectors
do not alter the line of the roof and generally come under
permitted development. If you live in a conservation area
or the building is listed, you will have to get advice from
your local planning office. Also, if the collectors are mounted
?on the front facade or impacts a neighbour's view, it would
be advisable to contact the planning office.
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What guarantees do you supply?
Our solar collectors carry a 10 year warrantee, hot water
cylinders 5 years and all other components carry a 1 year
warrantee. The system itself is guaranteed for 2 years although
it should last for 20 - 30 years.
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How long will the installation take?
For a normal system with a new hot water cylinder and solar
collectors, we would expect the installation to take two days.
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What maintenance is involved?
Our solar systems are designed to be very low maintenance,
drain-back systems are the lowest maintenance: the solar fluid
level should be checked periodically and the fluid replaced
after 10 years.
Pressurised systems have a pressure gauge which should be
monitored; also the fluid in the collector is subject to ‘stagnation’
temperatures of up to 200°C which can eventually degrade
the fluid so it needs to be replaced earlier.
Our hot water cylinders are made of copper and as such have
no anodes to replace.
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I don’t have a roof that faces south, does
that matter?
Not necessarily. Solar thermal systems are surprisingly tolerant
to variations in their mounting aspect and pitch.
It is possible to fit collectors on east and west facing roofs
and control between them as the sun moves throughout the day.
If you do not have any pitched roofs facing even remotely
south, collectors can be mounted on frames on flat roofs or
even on vertical walls.
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Systems
What’s the difference between a pressurised
and drain-back system?
The system must be able to withstand extremes of temperature.
In the winter, freezing fluid could cause damage to the collector
and pipework. In the summer, temperatures of 200°C are
possible which would cause the fluid to boil and cause excessive
pressures. The two systems cope with these issues in different
ways.
Pressurised systems hold the fluid at a pressure which increases
the boiling point of the fluid. They incorporate a pressure
vessel which allows the fluid to expand as it heats up without
increasing the system pressure.
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I’ve read that `low-flow’ systems are
good, is that true?
Low-flow systems use small bore pipework and pump the fluid
slowly through the collector. It is claimed that the fluid
picks up more energy from the absorber because it flows slowly.
What is really needed is ’variable flow’. In this
way the flow rate can be adapted to suit all weather conditions.
If the flow rate is too low, the collector plate will not
be cooled adequately and hence maximum energy will not be
extracted. The pipework must be large enough to allow the
peak flow rate in full sunlight. Normally 15mm pipe work is
suitable for most domestic systems. Our systems control the
pump speed proportionally to the temperature difference, hence
maximising heat transfer.
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I’ve got a combi boiler, can I still have a
solar system?
Solar systems rely on being able to store the energy collected
during the day for use when it is needed. It is essential
therefore, to fit a hot water cylinder. Most new combi boilers
can be supplied with solar pre-heated water and work on an
instantaneous basis as normal. Older combi boilers, which
cannot accept pre-heated water can still be used, but they
would be configured to provide back-up heating to the hot
water cylinder in the same way as a normal (non-combi) boiler.
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Aren’t direct systems more efficient than indirect
systems?
A direct system circulates the water from the hot water cylinder
through the solar collector. This has the advantage that only
one heat-exchange process takes place and so the system is
more efficient. The disadvantage is that the collectors can
have problems due to limescale build up in the collectors.
Also, as it is water and not antifreeze in the collector,
it may freeze in winter.
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Can I get a system to heat my house as well as the
hot water?
If your house is already very well insulated and energy efficient,
solar energy can make a useful contribution to the space heating
requirements. These systems are generally much more popular
in Scandinavia, where the housing stock is tradidtionally
very energy efficient. Typically a roof would have around
10m2 of collector area and a large storage cylinder of maybe
800litres. A secondary, back-up heating supply would be required
as a supliment.
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I want to heat my swimming pool but don’t want
it to cost the earth. Can solar energy help?
Solar collectors specifically designed for swimming pools
are available. Please call for details.
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Is it possible to run the pump from a photovoltaic
(PV) panel?
It is possible to add a photo-voltaic solar collector to run
the controller and pump for a solar thermal system. The advantage
is that no mains electricity is required. The photo-voltaic
collector, battery and controller can cost almost as much
as the solar thermal collector they are attached to. The amount
of energy they produce, in comparison is tiny. It is for this
reason that we generally recommend that a low-power solar
pump is driven from the mains supply unless the unit is mounted
remotely. Homeowners can choose to buy there electricity from
a renewable source. See our links page
for suggestions.
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What happens when I go on holiday in summertime?
The system can be safely switched off. The fluid will drain
into the drain-back reservoir and the collector on the roof
will simply get hot. They are designed to be able to tollerate
high temperatures when not actually operating.
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Solar
Collectors
Should I go for a roof mounted or roof integrated design?
Generally, roof mounting the collectors is the best option
when fitting to an existing roof. Mounting is much simpler
and there is no need to disturb the roof covering. Our roof
mounting collectors are low-profile and do not protrude beyond
the roof covering more than 100mm. In a new-build situation,
the collectors can be integrated into the roof covering, the
cost of the collector can then be offset to some extent by
the cost of the roof tiles that are displaced.
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I’ve heard that evacuated tubes are more efficient
than flat plate collectors, is that true?
Not always! By refering to the graph, it can be seen that
evacuated tubes are indeed more efficient at temperatures
above 40°C. At temperatures lower than that, a flat plate
collector is more efficient. In addition, an evacuated tube
collector of a given output will generally much more expensive
to buy than the equivalent output flat plate collector.
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Won’t the panels freeze in winter?
Because the fluid drains out of the collector into an insulated
reservoir when the pump is not running, there is no fluid
in the collector to freeze. Solaris systems are aditionally
filled with anti-freeze as an extra precaution.
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