| |
|
| |
|
Serious Talk & Hot Air
|
 |
|
A
solar air collector is not just a solar
air collector ...
 |
There is good reason to be critical when
considering construction and if you are
told that a system has an “extremely
high output”
A solar air collector’s technical
construction looks simple and can
actually be relatively easy to copy.
However, there are surprisingly many
pitfalls and the risk of construction
errors is high.
As a well-established manufacturer, |
|
SolarVenti Ltd. welcomes new competitors
as long as the competing product is well
constructed and will provide a durable
and good experience for the user.
Unfortunately, we regularly see
manufacturers - both in Denmark and
abroad - who develop solutions that are
badly thought through and who run
misleading marketing campaigns in an
industry that is still relatively young.
|
|
 |
Both ill-considered solutions and
misleading marketing campaigns damage
the industry as a whole as both have a
negative impact on a customer’s trust. |
|
Regardless of the solar air collector
you, the customer, end up choosing,
there are a few basic things that are
worthy of note when you read product
descriptions and other sales material.
|
|
Advertising rhetoric about extremely
high temperature output is misleading
|
The main benchmark for the evaluation of
the efficiency of a solar air collector
will always be the number of cubic
meters of incoming air per hour at a
given temperature.
Claims of, e.g., “250 % higher output
than similar products” are beyond the
realms of current technology and,
therefore, technically impossible, but
are also an example of misleading
marketing.
The fundamental principle behind
efficient dehumidification, ventilation
and supplementary heating from a solar
air collector is that the collector
blows large volumes of air into the
house at a temperature that is optimal
in relation to the volume of air.
The heat from the sun is used, out in
the panel on the roof or wall, to adjust
the temperature of the air that is blown
into the house so that it is close to -
and generally above - the indoor
temperature of the house.
In this way, the house is supplied with
automatic and cost-free dehumidification
and ventilation, which usually results
in noticeable savings on electricity and
heating bills as well as a good indoor
climate.
In brief: A well-constructed solar air
collector blows large volumes of air, at
a temperature adjusted to be as high as
possible, into the house when the sun
shines.
A solar air collector’s output of a
given temperature must
always be
quoted together with the number of cubic
meters of incoming air per hour -
otherwise the quoted temperature is of
no value as product data.
(See
measurement of the SolarVenti Model
performed at DTU
-
Denmark’s Technical University)
|
|
|
|
The
way in which the solar air collector
cools itself down is crucial
|
Today, it is standard for the modern
solar air collector to have the
electricity-producing solar cell built
into the actual panel. The solar cell
fits discretely into the panel and is
well protected against thrown-up pebbles
and other types of impact.
And the solar cell relinquishes its own
heat to the solar air collector panel
and, thus, into the house rather than
into the air outside, for the benefit
for the birds.
The protected position of the solar cell
within the panel imposes demands on the
“self-cooling” properties of the system.
Temperatures of up to 140 degrees
Celsius can be reached inside the panel
when the system is switched off and the
fan is not running. Neither the solar
cell nor the fan can cope with
temperatures of this magnitude.
Therefore, it is essential that the
solar air collector is able to cool
itself when it is switched off - i.e.
when the fan is not working.
Self-cooling of the solar air collector
by means of an extra fan which blows air
from inside the house through the solar
panel when the system is switched off is
not a good solution - for several
reasons. Firstly, and most importantly,
used air from inside the house that is
blown out through the panel will always
result in deposits of organic material
inside the panel in the long term.
This means that either the customer
himself or a service technician will
have to remove, dismantle and clean the
whole panel on the inside at some point:
a large and time-consuming job,
regardless of whether it needs to be
done after six months or after three
years.
Another reason why the extra fan inside
the solar air collector panel is a bad
solution is that there will always be
noise from the system when the sun
shines - and it is not possible to
switch the noise off!
A third reason is that the solar cell in
a panel with a separate cooling fan will
overheat and be destroyed if, by
unfortunate coincidence, the extra
fan/solar cell/cable or regulator does
not work for some reason or other.
Briefly: A solar air collector’s
self-cooling system must work in all
situations - without being heard. And it
is never a good idea to blow used air
from the house through a solar air
collector panel. A solar air collector
panel must be clean on the inside and
remain so.
|
|
 |
|
|
|
|
|
