Design and fabrication of a low cost data logger for solar energy parameters

Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.6, 2012

Design and Fabrication of A Low-Cost Data Logger for Solar
Energy Parameters

K. N. Akposionu (Corresponding author)
Department of Physics, Federal University of Petroleum Resources, Effurun, Nigeria.
kennbox@yahoo.com
A. O. C Nwokoye
Department of Physics and Industrial Physics, Nnamdi Azikiwe Universit, Awka, Nigeria.
ositonyk@yahoo.com

Abstract
In this research, the design and fabrication of a single board data logger system is presented. An LM35 linear
temperature transducer IC served as the temperature sensor device while a solar panel of dimension 6’x18’
coupled to a constant load driver circuit served as the solar irradiation variation sensor unit. At the heart of the
low cost logger is a Single Board Computer based on an 8 bit MCU embedded platform. Temperature readings
and solar voltage variations data were logged successfully. Results indicate consistency with normal weather
conditions. Logged data is then transferred to the personal computer for further analysis.
Keywords: Data logger, temperature, solar voltage, microcontroller, single board computer.

Introduction
A data logger is an electronic instrument (or specialized computing device in some cases) that records digital,
analogue, frequency or smart protocol based measurements over time (Nashtara, et al, 2006). It is an
all-purpose piece of measuring equipment that finds use in an extremely wide range of applications (Jakkree,
2009).
Data loggers have been successfully deployed in many scientific and industrial applications. Some of the
important areas in which data loggers are widely used include biomedical instrumentation (Cifrek et al, 2004),
power quality measurement (Yeary et al, 2001), automotive engineering (Illic et al, 2004), etc. The data logger
has to be portable, hand-held, battery-operated data collection device for collecting “real-world” data which can
be used as an interface connected to a computer or as a stand-alone instrument (Jakkree, 2009).
In this work, a digital data logger is designed for logging solar energy parameters. A single printed circuit board
(PCB) was used to fabricate the digital data logger. The output power from a solar panel and the ambient
temperature are logged. The accuracy of measurements and data are very important, hence, this research applies
the single-board computer designed in implementing the logger capable of storing data every 3 seconds.

1. Materials and Method
2.1 PCB Fabrication
The following steps were employed in this research to design, build and transfer the circuit to a printed circuit
board (PCB).
• Selection of a CAD tool that is compatible to speak with PCB related file formats.
• Preparation of detailed schematics using the CAD tool.
• Preparation of footprints of the components.
• Layout of the design in a board file.
• Build on copper clad fibre board via toner transfer.
The schematic completes the interconnections between different components. That is more in depth details of the
design than the functional diagram. The board file (.brd) gives details about the footprints of the component
packages.
This file contains sufficient information to process the fabrication. The .brd file is then printed for use in
toner transfer. Fig. 1a shows the PCB data logger fabricated in this work.
2.2 Module Design and Implementation
The data logger circuit is built around the Microchip PIC18F4550 Microcontroller. (Microchip Technology
Inc, 2011) The solar energy sensor circuit is made up of voltage dividers R2 and R3. R2 and R3 take the 12V -
15V solar panel voltage and scale it down so that the input to the analog to digital converter is below 5V as
required by the microchip.
The operational amplifier is used to measure the current draw. Using a 0.1Ω resistor between the negative wire

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Vol.2, No.6, 2012

of the solar panel and ground, the current going though the panel can be measured by measuring across the
resistor. To get useful current value, a non-inverting amplifier that amplifies that voltage to a bigger and easier to
manage voltage is used. This amplifier multiplies the voltage by 1 + R5/R4 = 48. This multiplies the measured
voltage by a factor of 48, thereby bringing it to a more suitable level. Component P5, the 20pin connector
provides the connection point of the sensor circuit unit to the single board microcomputer unit. This circuitry is
shown in Fig.1b.
The temperature sensing device used is the LM35 which is an integrated circuit sensor that can be used to
measure temperature with an electrical output proportional to the temperature (in oC). It has an output voltage
that is proportional to the Celsius temperature with a scale factor of 0.1V/oC. The LM35 does not require any
external calibration or trimming and maintains an accuracy of +/-0.4oC at room temperature and +/- 0.8oC over a
range of 0oC to +100oC.

The general equation used to convert output voltage to temperature is:
Temperature (oC) = Vout * (100oC/V). . . . (1)
The voltage variations sensed from the solar panel is divided down within the range of 0V – 5V suitable for the
ADC input of the single board computer. (National Instruments LM35 Datasheet, 2000).

3. Results and Discussion
The developed single board computer was used after the design to implement a data logging system. The energy
parameters samples were measured in Eburumede in Effurun, Delta State Nigeria, the coordinates
5034’17.12’’N and 5048’37.58’’ E were collected using a GPS device. The data logging system keeps track of
temperature and voltage variation across a constant load attached to a solar panel. The development of these
systems with the single board computer proved to be successful.
Temperature readings and solar voltage variations were sampled and logged at an interval of three (3) seconds
for a period of 3days within a time frame of 7hrs, 10hrs and 12hrs depending on the day.The temperature
and solar voltage readings obtained for three different days are displayed in figures 2-4 respectively.
The data logger was used to log temperature readings between 17.30hrs and 24.00hrs. From the graph, we
observe a decrease in temperature from about 31.2oC at 17.00hrs to about 28.9oC at a record time of about
19.05hrs. However, there was a slight increase in temperature to about 29.5oC at a record time of 19.58hrs
and thereafter decreases from 29.4oC at 20.00hrs to 27oC at 24.00hrs. Thus we observe clearly from the
temperature readings that the temperature was higher in the evening (17.30hrs) than in the early morning
(24.00hrs) which is consistent with normal weather condition. (Ojieabu et al, 2010). The solar voltage
variations obtained for the same date are presented in figure 2b
The solar voltage variation was logged. From fig. 2b, we observe a drop in voltage from 2.1V between 17.00hrs
and 18.00hrs to about 0.1V at about 18.58hrs. A 0V was recorded at 19.00hrs while between 19.30hrs to
24.00hrs show fluctuations in voltage value between 0.05V and 0.1V respectively.
The temperature readings for the second day were recorded for 12hrs starting from 24.00hrs to 12.00hrs as
displayed in fig. 3a.
A careful observation of figure 3a indicates a temperature drop from 29oC at 24.00hrs to 25oC at about 06.30hrs.
Thereafter, there was an increment in temperature to about 35oC at a record time of 09.30hrs which
decreased slightly to 30oC at 10.05hrs. A high temperature of about 42oC was recorded at about 14.00hrs
and thereafter decreases steadily to 25oC at 19.00hrs which was maintained till 24.00hrs. From our analysis,
we observe that temperature recorded in the morning was lower than that recorded in the afternoon which
again is consistent with normal weather conditions. (Ojieabu et al, 2010)
The solar voltage variations corresponding to the temperature readings obtained for this particular day are
displayed in figure 3b. Here the solar voltage variation is seen to increase from 0V to about 2.4V between
06:00hrs to 07:00hrs. It remained between 2V to 2.6V from about 08:00hrs to about 18:30hrs. Thereafter it
decreases to 0V.
The temperature reading for the third day was recorded between 24.00hrs and 10.00hrs as shown in figure 4a.
A temperature of about 25oC was obtained at 24.00hrs, which increased slightly and then falls steadily to about
23.9oC at about 05.57hrs. A temperature of 24.2oC was recorded at 07.05hrs, attains a maximum of 28.2oC
and decreased to exactly 28oC at 09.10hrs. From figure 4a, we observe that the temperature recorded is
lower in the early hours of the day than at other times.
The corresponding solar voltage variations recorded for this particular day are displayed in figure 4b.
From fig. 4b, we observe a very low voltage between 24.00hrs to 06.30hrs, thereafter, the voltage increases
gradually to about 26V at 09.05hrs. The curves presented in this research indicate that all values obtained in
this work are consistent with normal weather conditions.

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Vol.2, No.6, 2012

4. Conclusion
A data logger for solar energy parameters was successfully designed and fabricated. The data logger was
employed in logging temperature and solar voltage readings for 3 consecutive days. Values obtained in this
research for the days specified was consistent with normal weather condition. From the view of this study, solar
irradiation energy as a source of power supply is available between 06.30hrs to 05.30hrs, (Ojieabu et al, 2010)
while solar thermal energy is available at above 250C between 07.00hrs and 05.00hrs. These data collected
during the month on March, 2012, supports the development of solar energy systems as a lower cost option for
satisfying the many electric energy needs of this region. (Nwokocha et al, 2009)

REFERENCES
Cifrek, M.; Mrvos, S.; and Zufic, P. 2004. Portable data logging system for long-term continuous monitoring of
biomedical signals. Proc.12th IEEE Mediterranean Electrotech. Conf. (MELECON 2004), 12-15 May 2004, 1:
399-402.
Illic, S.; Katupitiya, J.; and Tordon, M. 2004. In-vehicle data logging system for fatigue analysis of drive shaft.
Proc. 2004 Int. Workshop on Robot Sensing (ROSE 2004), 24-25 May 2004, pp: 30-34.
Jakkree Srinonchat (2009), Improvement of a data logger system for renewable energy Asian Journal on Energy
and Environment As. J. Energy Env. 2009, 10(03), 142-148
Microchip Technology Inc. (2011),PIC18F4550 8-bit PIC® Microcontrollers,
http://www.microchip.com/wwwproducts/devices.aspx?ddocname=en010300,Accessed Thu Jun 14 18:30:26
2012
Nashtara, I., Robert, W., Philip, M. (2006): Z8 Encore Microcontroller Based Data Logging System. Assumption
University Journal of Technology 10(1): 63-67.
National Semiconductor Corporation (2000), Data Sheet LM35 Precision Centigrade Temperature Sensors,
https://www.national.com/ds/LM/LM35.pdf, Accessed on Thursday June 14 2012
Nwokocha C.O, Chineke T.C, Nwofor O.K and Okoro U.K (2009), Estimation of solar radiation in southeastern
Nigeria. International Journal of Natural and Applied Sciences, 5(3): 223-228
Ojieabu C.E and Okonigene R.E (2010), Solar Energy for Electric Power Generation in Benin City and Abuja
Nigeria. Journal of Engineering science and Applications (JESA) vol. 7 No. 1, pp 11-16
Yeary, M.; Swan, B.; Sweeney, J.; Culp, C.; and Archer, L.. 2001. An Internet based power measurement
technique. Proc. 18th Instrum. Measure. Technol. Conf. (IMTC 2001). 21-23 May 2001, 1: 628-33.

List of figures.

Fig. 1a: Fabricated Data Logger

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Vol.2, No.6, 2012

Fig.1b: Parameters sensing unit.

Fig. 2a: Temperature Readings on 24-03-2012

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Vol.2, No.6, 2012

Fig. 2b: Solar voltage variations on 24-03-2012

Fig. 3a: Temperature readings obtained on 25-03-2012.

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Vol.2, No.6, 2012

Fig. 3b: Solar voltage variations obtained on 25-03-2012.

Fig. 4a: Temperature Readings obtained on 26-03-2012.

Fig. 4b: Solar voltage variations obtained on 26-03-2012.

17

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Design and fabrication of a low cost data logger for solar energy parameters

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