Director,
T.E.(Terry)
Manning,
Schoener 50,
1771 ED
Wieringerwerf,
The
Tel:
0031-227-604128
Homepage:
http://www.flowman.nl
E-mail:
(nameatendofline)@xs4all.nl : bakensverzet
Incorporating
innovative social, financial, economic, local administrative and productive
structures, numerous renewable energy applications, with an important role for
women in poverty alleviation in rural and poor urban environments.
"Money is not
the key that opens the gates of the market but the bolt that bars them"
Gesell, Silvio The
Natural Economic Order
Revised English
edition, Peter Owen, London 1958, page 228
Edition 9:
The
following pages refer to the orientation of photovoltaic (PV) panels, the
support structure for the panels and its resistance to winds and shock. A
schematic drawing of a typical installation is also given. If you are more
interested in other aspects concerning installation, please return to the installation index.
Photovoltaic
systems are pointed North if placed in the Southern hemisphere, and South if
placed in the Northern hemisphere. The daily and global performance of PV
panels depends on the amount of energy they are able to collect, so they are
best if oriented seasonally (thus vertically, in accordance with height of the
sun with respect to the horizon) and hourly (thus moving east to west, in
accordance with the position of the sun during the day). In isolated locations,
systematic manual adjustments will rarely be feasible. The user must then
choose either to install an automatic tracking system, or point the panels in a
fixed position so as to obtain the best possible average daily power input.
With an automatic tracking system, the initial investment costs for the panel
support structure, and in some cases, long term maintenance costs, will be
higher, but on the other hand fewer PV panels may be required, and more water
will be pumped over a long term for each peak watt installed. With a fixed
system, a larger PV panel array will increase PV panel costs, the initial
investment in the tracking system will be eliminated, and slightly less water
will be pumped for each peak watt installed, but security of water supply is improved
and long term maintenance costs are reduced. There is no general agreement
amongst experts as to which alternative should be adopted. We believe that
safety of water supply must take precedence over all other aspects and
recommend that users adopt a fixed system in isolated locations, while for
rural villages we recommend that a three point manual tracking system without
any moving parts which can get lost, be used. The adoption of automatic
non-manual tracking systems is therefore the responsibility of the end-user.
Panels
should be seasonally tilted according to the latitude of the installation site.
Your solar dealer may have monthly tilting charts for your area. Choose the
correct tilt for your design month. However, if you live near the equator,
NEVER set the array in a horizontal position, as dust and debris will not wash
off. Make sure the tilt is sufficient to enable the panels to self-clean
themselves when it rains. In areas of low rainfall and in the presence of dust,
it may be necessary to wipe the panel surfaces periodically.
Panels are
fixed pointing due South/North. This means that they will tend towards peak
performance in the middle of the day, but will not deliver much current earlier
in the morning or later in the afternoon. However, fixed systems are INHERENTLY
SAFE as they cannot get "stuck" pointing either East or West. They
represent a compromise solution : global power generation is lower than it
might otherwise be, but the installation does not need any attention. They are
particularly suited to sites which are rarely visited and/or where the costs of
making regular visits greatly outweigh the benefits of extra power generation
deriving from the use of tracking systems. Fixed systems may or may not be
seasonally tiltable. If there is certainty that the installation will be
visited for a control three or four times a year, it is sensible to tilt the
panels according to the season. If no visits are foreseen, it is better to tilt
for the DESIGN MONTH you have chosen. An alternative is to allow a little
surplus power in your array, and tilt the array one angle away from DESIGN
MONTH optimum.
We believe that with small, highly efficient, systems such as those using Solar
Spring pumps, it is wiser to invest capital in a slightly larger fixed array
than in purchasing a tracking system.
Extremely
robust three point manual tracking supports without moving parts which can get
lost are available. Daily orientation can considerably extend the amount of
energy collected by the panels across the day, and therefore substantially
increase the amount of water pumped, although such benefits are not so
important with Solar Spring piston pumps as they are with traditional
technologies. Any user may change the orientation of the panels at any time, so
as to attain the most benefit in terms of water supply. In some cases, a
village may nominate a pump caretaker, and in such case, periodic orientation
of the panels during the day could fall amongst the caretaker's duties. The use
of the manual tracking systems is particularly indicated where installations
are sited in villages, or where people are regularly available to change the
orientation of the panels as required.
A number of
fairly reliable automatic tracking systems have come on the market in recent
years. Their inherent weakness is that if they fail, the panels may be locked
to the extreme East or to the West, which would be disastrous to the success of
the installation. We think it is better (eventually) to invest in the purchase
of one or more extra PV panels rather than purchase an automatic tracking
system. In any case, automatic tracking systems are used AT THE SOLE RISK AND
DISCRETION OF THE END USER.
You can
place your PV panels practically anywhere you wish, provided they are pointing
South if you live in the Northern hemisphere and North if you live in the
Southern hemisphere. They should,where possible, be inclined as recommended in
array tilt tables for the latitude in question, where available.
On the roof of your house or other
building, close to the water source
Mobile, on a trailer or similar, positioned close to the water source
Mobile but grounded, on a stable metallic structure, placed close to the water
source
On a pole or trellis structure, close, wherever possible, to the water source.
Positioning close to the
water source has been emphasised because the shorter the electric cable, the
lower the current loss. It is seldom, however, critical, and where necessary
the PV array can be placed as far away from the water source as is necessary to
obtain the best possible insolation.
The panels must generally be
free towards the South (if you live in the Northern hemisphere) or towards the
North (if you live in the Southern hemisphere) from obstacles such as
buildings, trees, and the like which may obstruct the sun's rays. It is still
better if obstructions to the east and west are also avoided, as this will
enable your PV panels to capture the sun's rays over much of the day, thereby
extending the number of hours the pump can work each day, and therefore the
amount of water pumped. Make sure the array is going to remain free from
growing weeds and from snow, rain or mud spatter which could shade one or more
panels and seriously reduce the capacity or your array. For this reason, the
bottom of the panels should always at least 1 meter from the ground.
In some areas risk of theft of PV panels and structures may be a major issue.
In others risk of damage by vandalism or sabotage or damage by animals persons
or things. Please remember to take such factors into account when siting your
array.
You may wish to use your
Solar Spring pump and accompanying array as mobile equipment which can be moved
from place to place according to your requirements from time to time.
Fixed support structures
should in any case be firmly anchored in concrete and such as to be able to
withstand the worst weather conditions ever recorded at the site. The support
structure should have been installed several days BEFORE the installation of
the pump, so as the ensure that the concrete used has had time to set.
Please
follow the instructions given by the respective manufacturers.
Correct
installation of panel supports is the responsibility of the end use and/or of
the installer he has nominated. No liability for damage whether direct or
indirect to persons or things howsoever caused by failure of the support
structure to withstand winds atmospheric conditions generally or shock shall
attach to the pump supplier.
Subject to the above
limitation as to liability, a 76mm diameter hot dip galvanised mild steel
support pole is usually considered sufficient. The pole should be anchored
(where possible, as stated above, in a concrete bedding) at least one metre
below ground level, and should project at least 2 metres above the ground. Height
is not critical, but higher structures may be better suited to capturing the
sun's rays earlier in the day and later in the evening.
Menu installation Solar Spring pumps.
Some recommended technologies.
List of attachments to the Model.
Typical list of graphs and
drawings.
List of abbreviations used.
List of key words.
Documents for funding
applications.
