ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY & ENVIRONMENT
AZOJETE December 2019. Vol. 15(4):919-928

Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria.
Print ISSN: 1596-2490, Electronic ISSN: 2545-5818

www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 919

ORIGINAL RESEARCH ARTICLE

PERFORMANCE EVALUATION OF TRACKING AND NON-TRACKING PV SYSTEMS IN
SCOTLAND, UK

F. M. Kajiama1*, G.M. Ngala1, M. Abdulkadir2 and W. G. Fruh3
(1Department of Mechanical Engineering, University of Maiduguri, P. M. B. 1069, Maiduguri, Nigeria

2Department of Electrical and Electronics Engineering, University of Maiduguri, P. M. B. 1069, Maiduguri, Nigeria
3School of Engineering and physical sciences Heriot-Watt University Scotland UK)

* Corresponding author’s email address: timakaj@yahoo.com

1.0 Introduction
Solar energy is an important component of renewable energy resources. Edinburgh is a location
that has variation in sunshine hours with high latitude; hence to capture solar radiation in the
application of solar photovoltaic (PV) technology it is necessary to apply a technology that
optimizes the solar resources in the location. Solar tracking system is a suitable option that
could be used in capturing both direct (beam) and diffuse radiation. This will enhance
performance at low cost. A solar Tracking system is a device which direct solar panels or
modules toward the sun. These devices change their orientation throughout the day to follow
the suns path to maximize energy capture. The work under study will be achieved by modelling
the resource data (monthly and daily irradiation record) for higher power output during winter
months, with the use of the tilt-angle solar PV tracker (solar power world, 2013).

Solar tracking increases the energy received by the photovoltaic modules which in turn
increases the annual and daily power output, but its application will be more expensive and
more complex than fixed mount. The solar tracking system will be cost effective in cases where
there is sufficient output power throughout the year. The tracking system can be defined as a
device which manoeuvres with respect to the movement of the sun. The device can decrease

ARTICLE INFORMATION ABSTRACT

Solar energy is an important component of renewable energy
resources. Solar tracking system is a suitable option that could be
used in capturing both direct (beam) and diffuse radiation. To
investigate the performance of tracking and non-tracking PV
systems, solar angles were estimated based on solar geometry and
combined with global and direct radiation measurement covering a
year. Results showed that using horizontal fixed panels or tracking
the sun about single axis was worst to boost the energy collection
of the panels, while tracking the sun about two axes or using fixed
but optimally tilted panels was found to be better and efficient.
With an annual electricity of 67.3 and 66.3 kWh/h respectively and
an improvement of 3.65 and 2.12%. This implies that fixed tilted
panel will be suitable to be employed in the region with lower
irradiance as Edinburgh.

© 2019 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserved.

Submitted 11 October, 2018
Revised 15 June, 2019
Accepted 19 June, 2019

Keywords:
Non-tracking Panels
Tracked Panels
Global Radiation
Direct Radiation.

http://www.azojete.com.ng


Kajiama et al: Performance Evaluation of Tracking and Non-tracking PV Systems in Scotland, UK. AZOJETE, 15(4):919-
928. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 920

the angle of incidence of the radiation beam on its surface by rotating on its axis which in turn
increases the direct radiation acting on its surface. Solar Tracking device can be classified
according to its rotation as a single axis or two (dual) axis tracking. Single axis tracking device
follows the direction of the sun either across east to west in the sky or up and down while two
axis tracking device follows the sun from east to west and it tilts the modules with respect to
movement of the sun. (solar power world,2013). Both devices are being investigated in this
study, they are said to operate with electrical/thermal power gain of about 20-40% higher than
fixed panel (Ryan, 2010). There is not any trading importance for both direct and diffuse
radiation, because Edinburgh lies in higher latitude it’s always cloudy and rainy.

Standard photovoltaic are used in this study because they are not expensive, and simple to use.
They have the added advantage of using both component of irradiation that is diffuse and
direct radiation. When tracking is introduced it decreases incident angle to the direct radiation
and increases energy production. Photovoltaic modules received maximum radiation when the
sun strikes on it at right angle. When tilted to the sun, the collection of energy by the module
becomes lower, and therefore optimal installation of fixed or single-axis devices depends on
latitude of the site. The collected energy not only depends on the panel’s angle to the sun,
which depends on latitude, day of year and time of day, but also on local weather conditions,
clouds. It is therefore important to use local radiation information to assess the expected
amount of energy collected in a year (Duffie and Beckman,2013).

Areas with higher radiation data tend to have 30% increase with single axis tracking while 20%
increase was observed in areas with lower radiation data when compared to fixed photovoltaic
module. Shadow geometry in azimuth tracking was used in his photovoltaic plant design
(Lorenzo et al, 2002). Percentage increase in mean surface irradiance due to tracking for 18
temperate sites was reported (Nann, 1990) and 34% average increase in irradiance resulted by
using single axis instead of fixed panels with mean irradiance of 29 to 37% while 39% increase in
average with two axis tracking is capable of increasing the mean irradiance from 33 to 42% than
fixed panel. Therefore, transferring from single to dual will result to irradiance mean increase of
about 3 to 7%.

The main purpose of this study is to model and simulate the behaviour, define and compare the
performance of a horizontally fixed photovoltaic panel, a single-axis tracking PV Panel and a
two- axis tracking PV panel system. It also intends to evaluate the performance of tracking and
non-tracking PV systems in Scotland choosing Edinburgh as the location based on hourly global
horizontal radiation data. The outcome would enable renewable energy planners to determine
which of the solar technologies is most suitable to be implemented in Edinburgh. Successful
installation of such a renewable technology would assist in meeting the growing energy
demands of the country and in the reduction of environmental problems associated with the
use of fossil fuel such as Green House Gases (GHG) whilst promoting the use of renewable
energy.

In order to reduce the electricity cost generated, a configuration of three tracking modes
namely seasonal, one axis N-S tracking and diurnal tracking are incorporated into the system.
More than 120%of electrical energy was achieved by fixed panels with an azimuth tracking in
Damascus, Syria (Al-Mohamad, 2004). Another theoretical analysis (Chang, 2009b) on gain of
ISNA (Inclined South North single Axis) based on extra-terrestrial radiation for different latitudes

http://www.azojete.com.ng


Arid Zone Journal of Engineering, Technology and Environment, December, 2019; Vol. 15(4) 919-928. ISSN 1596-2490;
e-ISSN 2545-5818; www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 921

and period of time for areas having latitude lower than 65 with tracking panels showed the ratio
of collectible annual radiation than fixed panel to be approximately 1.5, this is said to increase
gradually for latitudes with a higher value of about 1.8 in Arctic zone. In Taiwan, (Chang, 2009c)
discovered a 3.1% increase in annual energy capture for a month by using tilted angle
photovoltaic panel over the single axis tracking.

Horizontal east west axis tracking panels were said to be lower than that of inclined south north
single axis (ISNA) tracking panel when radiation was collected annually (Chang, 2009b).
Applying single axis tracking system to fixed panels (Chang, 2009a) observed that using single
axis tracking in Taiwan for assessing photovoltaic performance; an improvement of 19% was
achieved. Chang (2009c) also predicted that single axis tracking with an optimized inclination
rotational axis is said to experience about 50% higher irradiance than fixed panel but at latitude
lower than 65°.

Identical panels in Germany were tested side by side and higher Energy of about 118% and
130% was obtained with one axis azimuth tracking and dual axis tracking panels, respectively,
than fixed slope panels (Helwa et al., 2000). For some days, with north south tracking system
showed a gain of 30 to 45% higher in power output than fixed photovoltaic module. In the
same period 50% gain in solar energy was found by orienting horizontal module to two axes
tracking in a cloudy day (Kelly et al., 2009).

A study carried out by Lubitz (2011) shows that tilting an azimuth tracker between two and
twelve times per year manually produces better gain in irradiation than fixed, south facing panel.
Lubitz (2011) also found that at optimum tilt angle, converting due south fixed panels with
azimuth single axis tracking will yield higher gain. An investigation on optical performance of
inclined south north single axis tracking photovoltaic modules, estimated mathematically the
annual collectible radiation on fixed and tracked modules and found out a tracking system is
more efficient than fixed panel (Li et al., 2010).

2. Material and Methods
2.1 Solar Angles
In order to be able to track the PV panel one must know the exact direction of the sun ray. This
can be obtained by sun path: the equatorial or global system and the azimuthal or local system.
Azimuthal system makes use of altitude (α) and azimuth angle )as shown in Figure 1, while
Equatorial system uses declination (δ) and hour angle (w) as shown in Figure 2.

Figure1: Sun position in the sky is typically given as an azimuth and altitude angle. (Solar
Position,1994-2012).

file:///C:/Users/user/Downloads/azojete143/www.azojete.com.ng


Kajiama et al: Performance Evaluation of Tracking and Non-tracking PV Systems in Scotland, UK. AZOJETE, 15(4):919-
928. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 922

Figure 2: Solar Angles ( ), Declination (δ), Hour Angle ( ), Altitude (α), Azimuth ( ), and
Zenith (Z).

The formulas below where source from (Duffie and Beckman, 2013)
The azimuth angle, , can be expressed as;

( ) = Cos-1(Sin α * Sin φ – Sin δ/Cos α * Cos φ) (1)
The altitude or (elevation) angle, α can also be expressed as;
α= Sin-1 (Sin δSin ϴ+ Cos δ Cos ϴCos (HRA))

And α = 90-ϴ (2)
The equatorial system has the following expression; Declination :( Duffie and Beckman, 2013)

δ = 23.45◦ Sin 360◦ (n – 80) /36 (3)
Hour Angle; w: = 15◦ (12 – T) (4)

The constant angles defining the orientation and location of the tilted plane:
ϒ, Solar Azimuthally angle. Solar azimuth angle ( ) is defined as the horizontal angle which is
measured from south in the Northern hemisphere to the horizontal projection of the sun rays
(Duffie and Beckman, 2004).
n is the time of year

δ, Declination (δ) angle is the angle between the line joining the sun and the earth and its
projection on the equatorial plane. Declination angle is zero at the venal (20/21 March) and
autumnal (22/23 September) positions.

W, Hour angle w is the angle between the meridians passing through the sun and the meridian
of the site. Hour angle is zero at solar noon and increases toward the east. (Markvart, 1996).

Φ, Latitude φ is defined as the number of degrees north or south of the equator. Or the angle
made by the radial line joining the location to the centre of the earth with the projection of the
line on the equatorial plane, rotating axis of the earth intersect the surface of the earth at 90°
latitude (north pole) and −90° latitude (south pole). Each location on the earth surface can be
found by intersection of longitude and latitude angle.

http://www.azojete.com.ng


Arid Zone Journal of Engineering, Technology and Environment, December, 2019; Vol. 15(4) 919-928. ISSN 1596-2490;
e-ISSN 2545-5818; www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 923

Solar altitude angle refers to how high in the sky the sun is. It is described in terms of solar
zenith angle which is the vertical angle between the sun rays and a line perpendicular to the
horizontal plane through the point (ϴz = 90 - α).Equation (3) and (4) are used in equatorial
system, whereas (1) and (2) are used in azimuthal system. An important formula which indicates
the hour angle, at which the sun rises and set, was depending on the latitude and season (Agee
et al., 2007);

Wsr, ss =+ or – Cos-1(−tan φ tan δ). (5)

In most renewable energy projects, it is very important to know how long it will take for the
investment to pay for itself. This is why payback period will be calculated. With the following
advantages: A longer payback period indicates capital is tied up. Focus on early payback can
enhance liquidity. Investment risk can be assessed through payback method.

Payback Period = Installation cost
Savings cost−Maintenance cost

2.2 Methodology
The methodology developed to complete the project is based on the following:
Latitude, longitude, time zone, local time (hours and year). The location was used for the
computation of solar angles at different hours of the day for each month. The hourly global
radiation and the daily ‘synoptic’ direct and global radiation for Edinburgh for the year 2010-
2011 were obtained from the United Kingdom Met. Office through the British Atmospheric Data
Centre (Midas, 2012) and is expressed in kWh/m2. For fixed horizontal photovoltaic panel the
tilt angle is zero. Incidence angle ϴwas calculated using the equation below.

Cos ϴ = Sin α (6).
where:
ϴ= incidence angle α = elevation angle
An excel spreadsheet was used to calculate incidence angles for varying elevation angles.
For tilted surfaces facing south the angle of incidence was calculated using the equation below:

Cos ϴ = Sin α Cos β – Cos α Sin β Cos A (7)
where:
α = Elevation angle (degrees) β = Tilt or slope (degrees), = Azimuth angle (degrees). An excel
spreadsheet was used to calculate incidence angles for varying elevation angles of tilted
surfaces facing south.

From SYNOPTIC Radiation, the daily direct radiation and daily global radiation for each month
at a specific date of the year was deduced respectively. The ratio of the direct to the global
radiation is shown in Figure 3. This shows that the direct radiation is only a few percent of the
global radiation in the summer but was much higher in some winter months, typically around
20% between November and February, with an unusually sunny December in Edinburgh.
To Split hourly global into direct radiation and diffuse radiation at different hours of the day for
each month the following equations were used to calculate direct radiation and diffuse radiation
respectively.

Direct = Global Radiation * Ratio Diffuse = Global Radiation *(1-Ratio) (8)

file:///C:/Users/user/Downloads/azojete143/www.azojete.com.ng


Kajiama et al: Performance Evaluation of Tracking and Non-tracking PV Systems in Scotland, UK. AZOJETE, 15(4):919-
928. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 924

Global Radiation was obtained from MET Office data.
Knowledge of view factor is important in estimating the solar radiation incident on the surface
of a collector. And View factor was calculated for fixed horizontal PV system using the formula
below.

View Factor = Cos (Incidence angle) (9)

View factor for tilted surfaces was calculated using the formula below

View Factor = COS (Incidence angle) (10)

The radiation captured by the collector or received radiation was calculated using the equation
below;
Received Radiation = View factor * Direct Radiation Diffuse radiation.
Performance curve was determined from the generic example in Twidell and Weir (pg., 222 I-V
characteristic). This is because PV modules create a flow of current that’s described as direct
current (DC) because the electrons move in just one direction. As sunlight strikes the PV cells,
the electrons move off the cells and through a load (any piece of electrical equipment) before
heading back to the cells, all while staying in a straight line.
The power was calculated using the equation below, as

P = IV (11)
where:
I=Current (Ampere) and V=Voltage (Volt). A straight-line graph was obtained with a slope of
0.068 0.0004

3. Result and Discussions
3.1 Fixed horizontal Panel
As the view factor for fixed horizontal panel is shown in Figure 3. The view factor for two-axis
tracking is always equal to one; both single axis and fixed panel has a view factor of cosine of
incidence angle, summer month (May to Sept. 2012) has a higher view factor than winter month
(Nov. to Jan. 2012) as seen in the graph, with the resulting electricity generated as shown in
Figure 4

Figure 3: View factor for fixed horizontal panel

http://www.azojete.com.ng


Arid Zone Journal of Engineering, Technology and Environment, December, 2019; Vol. 15(4) 919-928. ISSN 1596-2490;
e-ISSN 2545-5818; www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 925

Figure 4: Daily electricity generated from fixed horizontal panel (kWh)

3.2 View factor for other Panels
Optimum tilt PV panels makes almost identical in summer and winter month but single
horizontal axis tracking panel did not achieved that whereas two axes tracking always has a view
factor of one as shown in Figure 5.

Figure 5: Graph of view factor from the five systems
3.3 Electricity Production
Results obtained by simulation in this work are shown in Tables 1 and 2. It is seen that two axis
sun tracking system generate 54.03% more electricity than the fixed tilt, single axis tracking and
horizontal fixed PV panel, with a clear weather HT = 7.95 Kwh/m2 day in July 24, 2011 which is
much higher than single axis tracking and horizontal fixed PV panel which generates about the
same amount of electricity annually.
The simulation result shows that the highest daily electricity generated from horizontal fixed
PV panel is 53.612% on July 24, 2011, with a total daily received radiation HT = 7.88412 Kwh/m2
(warmest month with an average temperature of over 20 °C ) and 31.2423% on May 21,2011,
with total daily received radiation HT = 4.59445 Kwh/m2 (partly cloudy). In general, the power
generation of horizontal fixed PV panel usually increases much more on clear weather. But in
some partly cloudy days, the increase in power generation will still be obvious which may be
due to the variation of diffuse radiation from ground, sky or cloud. The monthly result also
shows that the increase in power generation from the system is around 16.61972 Kwh and
9.685111 Kwh respectively which is from a period of July and May with an annual output of

file:///C:/Users/user/Downloads/azojete143/www.azojete.com.ng


Kajiama et al: Performance Evaluation of Tracking and Non-tracking PV Systems in Scotland, UK. AZOJETE, 15(4):919-
928. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 926

64.94633 Kwh/h. which can represent the typical summer weather in Edinburgh but also there
are many daily performance in August, September and June which also represent the weather in
summer.
With respect to single axis tracking the simulation results indicates that the electricity generated
will be higher or larger in areas with abundant solar energy resource (that is high HT). Then the
present daily generated power result (51.3849%) which was made in Edinburgh with low solar
energy resource with an annual output of 65.01102 Kwh. 3.65% Improvement was also obtained
by two axis sun tracking system and an improvement of 2.12% from fixed tilt PV panel

Table 1: Annual Electricity Generation for the Five Systems
System Horizont

al Fixed
panel

Fixed Tilted
Panel

Horizontal single
axis tracking

Vertical
single axis
tracking

Two axis
tracking

Annual Electricity 64.9 66.3 65.0 63.2 67.3

Table 2: Monthly Daily Electricity for five PV systems, Kwh.

Month
Horizontal
Fixed

Fixed
Tilted

Horizontal single
axis

Vertical single axis
tracking

Two axis
tracking

Jan 2.55 2.76 2.62 2.51 2.83
Feb 1.44 1.59 1.53 1.32 1.66
Mar 7.17 7.28 7.26 6.98 7.36
Apr 7.28 7.34 7.37 7.16 7.43
May 9.68 9.70 9.76 9.51 9.79
Jun 5.73 5.75 5.64 5.49 5.81
Jul 16.61 16.63 15.92 16.36 16.74
Aug 5.99 6.06 6.07 5.75 6.13
Sep 4.12 4.22 4.25 4.00 4.32
Oct 2.70 2.86 2.78 2.62 2.93
Nov 1.47 1.67 1.54 1.37 1.75
Dec 0.15 0.40 0.22 0.17 0.49

3.4 Cost Benefit Analysis / Pay Back Periods for the Systems
The following price per KW was assumed for Non- Tracking System Calculations.
Installation cost of non-tracking is (£500.00 per 1kW of 1 m2 area) (PV panel guide, 2011).
Cost of maintenance £30.00 per year.
Savings £77.00 per year calculated from percentage improvement (using an electricity price of
13.95p per kWh) using the formula below;
Therefore; Payback Period = 10 years
Assumptions;
The following price per KW was assumed for Tracking System Calculations
Installation cost for tracking is (£4,000 per 1kW of 1 m2 area) of 1 m2 area (Energy saving trust,
2012, Eco experts, 2007).

http://www.azojete.com.ng


Arid Zone Journal of Engineering, Technology and Environment, December, 2019; Vol. 15(4) 919-928. ISSN 1596-2490;
e-ISSN 2545-5818; www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 927

Cost of maintenance £50.00 per year.
Savings £78.00 per year it is also calculated from the improvement using same electricity price
as the non-tracking system.
Payback Period = 14 years 2

4. Conclusions
These results indicated that two axis sun tracking was an effective technique to boost the
radiation collected by solar panel which always points the panel directly to the sun. The only
difference in performance of the photovoltaic system in summer and winter is the module
temperature which is said to be lower in winter. The result shows that single axis sun tracking
will not be of important to the location (Edinburgh). The present simulation result shows that
tracking PV panel will only be useful in areas with high solar energy resource and the cost is
much more expensive as compared to conventional PV panel.
It is concluded that fixed tilted panel will be suitable to the people in Edinburgh because two
axis tracking manoeuvres with respect to the movement of the sun, horizontal fixed panel can’t
capture enough energy therefore, fixed tilt will be the best for the location (Edinburgh)
according to my simulation result. As shown in figure 4 and 5 respectively.

References
Agee, JT., Obok-opok, A. and Lazzer, MD. 2007. Solar Tracker Technologies: Market trends and
field applications. Advanced Material Research, 19: 339-344.
Al-Mohamad, A. 2004. Efficiency improvements of photovoltaic panels using a sun- tracking
system. Applied Energy, 79: 345-354.
British Atmospheric Data Centre. 2012. Global Radiation Observation. Met office- MIDAS Land
Surface Station Data, Edinburgh http://badc.nerc.ac.uk/data/ukmo-midas. (Accessed 20thJune,
2012).
Chang, TP. 2009a. Performance study on the east-west oriented single-axis tracked panel.
Energy, 34 (10): 1530-1538.
Chang, TP. 2009b. The gain of single axis tracked panel according to extra-terrestrial radiation.
Applied Energy, 86: 1074-1079.
Chang, TP. 2009c. Output energy of a photovoltaic module mounted on a single axis tracking
system. Applied Energy, 86: 2071-2078.
Duffie, JA., and Beckman, WA. 2004. Solar Engineering of Thermal Processes. 3rd ed. John
Wiley and sons Canada, pp. 56-63.
Duffie, JA. and Beckman, WA. 2013. Solar Engineering of Thermal Processes. 4th ed. John Wiley
and sons Canada, pp. 38-40.

Energysavingtrust. 2012. Costs, savings and maintenance. [online] Available at:
http://www.energysavingtrust.org.uk [ Accessed 9, August 2012].
Helwa, N., Bahgat, A. and El Shafee, A. 2000. Maximum collectible solar energy by different
tracking systems. Energy Sources, 22: 23- 34.

http://badc.nerc.ac.uk/data/ukmo-midas
http://www.energysavingtrust.org.uk
file:///C:/Users/user/Downloads/azojete143/www.azojete.com.ng


Kajiama et al: Performance Evaluation of Tracking and Non-tracking PV Systems in Scotland, UK. AZOJETE, 15(4):919-
928. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: timakaj@yahoo.com 928

Kelly, N., Gibson, A. and Thomas, L. 2009. Improved photovoltaic energy output for cloudy
conditions with a solar tracking system. Solar Energy, 83: 2092-2102.
Li, Z., Liu, X. and Tang, R. 2010. Optical performance of inclined south-north single –axis tracked
solar panels. Energy, 35: 2511-2516.
Lorenzo, E., Perez, M., Ezpeleta, A. and Acedo, J. 2002. Design of tracking photovoltaic systems
with a single vertical axis progress in photovoltaics. Research and Applications, 10(8): 533-543.
Lubitz, WD. 2011. Effect of manual tilt adjustments on incident irradiance on fixed and tracking
solar panels. Applied Energy, 88: 1710- 1719.
Markvart, T. 1996. Solar electricity. 2ndedition.John Wiley and sons Inc. New York: pp170-178.
Nann, S. 1990. Potentials for tracking photovoltaic systems and V-troughs in moderate climates.
Solar Energy, 45(6): 385-393.
Mayfield, R. 2010. Photovoltaic Design and Installation for Dummies. Wiley Publishing Inc.
Canada: pp36-78.
The PV panel guide. 2011. Costs of PV Solar panel installation. [online] Available at:
http://www.PVpanelguide.co.uk [ Accessed 9 August 2012].
The Eco Experts. 2007. Solar Tracker cost, Dual Axis and Single Axis. [online] Available
at:<http://www.theecoexperts.co.uk> [Accessed 20 August 2012]

http://www.pvpanelguide.co.uk
http://www.theecoexperts.co.uk
http://www.azojete.com.ng