KING FAHD UNIVERSITY OF PETROLEUM & MINERALS COLLEGE OF ENGINEERING ELECTRICAL ENGINEERING DEPATMENT Senior Project Final Report - 121 Design and Implementation for Maximum Power Point Tracking for Photovoltaic Generators Advisor: Dr. Chokri, Belhadj Ahmed Mufti 200717070 Ahmad Al-Shammari 200736450 Abdullah Al-Shehri 200739630 Abdullah Al-Omran 200832100 Abdulillah Al-Saaedi 200832820
15th of December, 2012

ACKNOWLEDGEMENTS
We would like to express our gratitude towards all the people who have contributed their precious time and efforts to help us in completing this project.
We would like to thank Dr. Chokri Belhaj Ahmed, our Project Supervisor for his guidance, support, motivation and encouragement throughout the period of this project.

We would like to thank Dr. Alaa El-Din Hussein Ahmed, for his precious time and efforts to help us in completing this project.

We would also like to thank the Department of Electrical Engineering for providing us with a good environment, facilities and the equipment to complete this project.

We are also grateful to the lab technician Mr. Edmana Abbas for support and help.

ABSTRACT
Solar energy has become an alternative source of energy. Several researches have been focused on the photovoltaic (PV) systems efficiency development and the availability of this technology. Today, PV power generation has gained more consequence due to its numerous advantages such as fuel free, no maintenance and environmentally green. This report gives a smart approach for the improvement of the PV control performances. Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to nonstop deliver the highest possible power to the load when even when atmospheric condition change suddenly. In order to achieve this goal, a special interest was focused on both Perturb and Observe method and Open Circuit Voltage method. This report presents a complete study of the MPPT controller to assure a highest possible PV system performance. A DC/DC buck converter feeding a load is achieved. Results are given at the end of the report.

LIST OF CONTENTS
LIST OF ABBREVIATIONS v
LIST OF FIGURES vi
LIST OF TABLES viii
CHAPTER 1: INTRODUCTION 1 A. Solar Panels 1 B. Characteristics of the Panel 3 C. MPPT 4 D. DC-DC Converters 8 E. Cassy Lab 12
CHAPTER 2: TECHNIQUES 13 A. Perturb and Observe 13 B. Incremental Conductance 14 C. Open-Circuit Voltage 15 D. Short-Circuit Current 16
CHAPTER 3: PERTURBATION AND OBSERVATION METHOD 17 A. Theoretical 17 B. Experimental 19
CHAPTER 4: OPEN CIRCUIT VOLTAGE METHOD 23 A. Theoretical 23 B. Experimental 24
CHAPTER 5: CONCLUSION 30 REFERENCES 32

LIST OF ABBREVIATIONS
V Voltage
I Current
P Power
ISC Short Circuit Current
VOC Open Circuit Voltage
MPP Maximum Power Point
MPPT Maximum Power Point Tracking
PV Photo Voltaic
P&O Perturb and Observe k Constant of Proportionality
D Duty Cycle n Harmonic Variable
C Condition

LIST OF FIGURES
Figure1. The Electric Field Created by Diffusion of Electron 2
Figure2. Power Curve in Two Days 3
Figure3. IV Characteristics of a Solar Panel 4
Figure4. PV Characteristics of a Solar Panel 4
Figure5. IV and PV Curves at Different Load Variations 6
Figure6. IV and PV Curves at 9:00 A.M 6
Figure7. IV and PV Curves at 9:00 A.M and 9:30 A.M. 7
Figure8. IV and PV Curves at 9:00 A.M, 9:30 A.M. and 10:45 A.M. 7
Figure9. DC Converters General Circuit 8
Figure10.Basic Circuit of a Buck 9
Figure11. MOSFET and Power Diode 10
Figure12. Function Generator and Oscilloscope 10
Figure13. Connections of a DC-DC Buck Converter 11
Figure14. Connection of a Buck Converter 11
Figure15. Example of some functions available in the CASSY Lab 12
Figure16. Characteristics PV array Power Curve 14
Figure17. Incremental Conductance 15
Figure18. P&O Algorithm Chart 18
Figure19. Cassy Lab Connection 19
Figure20. Condition of P&O 19
Figure21. Duty Cycle Formula 20
Figure22. Function Generator Settings in CASSY Lab 21
Figure23. Block Diagram of Voltage Based MPPT 23
Figure24. Function Generator for the Duty Cycle 24
Figure25. Output Voltage using Oscilloscope 25
Figure26. Function Generator in CASSY Lab 25 Figure27. Duty Cycle and Output Voltage without Capacitor and Inductor 26 Figure28. Duty Cycle and Output Voltage with Capacitor and Inductor 26 Figure29. Function Generator Using CASSY Lab 27 Figure30. Duty Cycle and Output Voltage with 500Hz Frequency 27 Figure31. Open Voltage Formula 28
Figure32. Output of DC-DC Converter with a Variable Load 29

List of Tables
Table I. Current, Voltage and Power Values at Different Load Variations 5
Table II. Major Characteristics of MPPT Techniques 16
Table III. Summary of P&O Algorithm 17
Table IV. Condition Results of P&O 20
Table V. Duty Cycle Results 22

CHAPTER 1: INTRODUCTION
Renewable energy lately increases rapidly, due to the crisis of nonrenewable resources. Fortunately, there are different kinds of sustainable energy that friendly to the environment, such as solar energy, wind energy, biomass energy, geothermal energy and much more. In this project we will focus only on the solar energy, and particularly in the techniques of maximum power point tracking (MPPT) to increase the efficiency of the photovoltaic system.

There are studies shows that we can deliver only 30%-40% solar energy into electrical energy. Realistically, they only reach efficiency from 10% to 17%. However, in this part maximum power point is necessary to increase the efficiency of the photovoltaic cell, and there are different techniques that it will mention later on this report. First of all we have to understand the concept of converting light to electrical energy.

A. Solar Panels
The photovoltaic cell (PV) made of semiconductors (e.g. Silicon, Gallium arsenide). Basically; the PV cell is a p-n junction, the donors with more valence electron exist in the n- side, and the acceptors with less valence electron (holes) exist in the p-side. Next, the electrons in n-side diffused in the p-side to achieve the equilibrium in the junction, and the moving of electrons creating behind it an electric field; this electric field pulls the electrons and holes in opposite directions which creating current flow in one way only. The solar system built by many PV cells that could be connected in parallel or in series, depend on the function of the system used for. [1]

Figure(01): The electric field created by diffusion of electrons [2]

Silicon is the most widely used material for making PV panels. Although other materials can be used for making PV panels, Silicon features with the high availability in the Earth’s crust. Silicon and other semiconductors can be crystalline, multicrystalline, polycrystalline, and microcrystalline (amorphous). [1]

Crystalline (Monocrystalline silicon):
Crystalline silicon has an ideal structure of silicon atom, which makes it the most efficient ones. However, it is the most expensive ones, because it requires careful, and slow manufacturing process. [2]

Multicrystalline:
The structure of multicrystalline is random, so the efficiency is lower than crystalline silicon. In the other hand, the process of manufacturing is simpler and cheaper. [1]

Amorphous:
Amorphous silicon is the non-crystalline form of the silicon atom. The manufacturing process is the simplest, which also makes it the cheapest one. However, amorphous silicon absorbs photons better than crystalline, so this ability makes it preferred over crystalline in the cloudy days. [3]

B. Characteristics of the Solar Panel:
The university has two solar panels and we used both of them in our project.

Figure (02): The solar Panels above building 59 at KFUPM
Here is a table of the solar panel characteristics:

Table I: Solar Panel Characteristics

Solar Panel | Manufacturer | National Solar Systems | Model | NSS-24150M | Max System Voltage | 1000 V | Stand test condition | 1000 W/m2 , AM1.5 , 25C | Max Power | 150 W | Max Power Voltage | 36 V | Max Power Current | 4.61 A | Open Circuit Voltage | 43.2 V | Short Circuit Current | 4.49 A | Net Weight | 16.0 Kg | Size (L\B\T) | 1580,808,46 mm | Out Tolerance | ±5 | Made in | Chine |

We used one of the panels to measure the power in the course of two days. The days had different irradiations due to the weather conditions. The power can be seen at figure ().

Figure (03): Power Curve in two days
As we can see from the graph, the power was calculated directly from the PV panel for approximately 2 days. The 2 days were a little bit cloudy and so the maximum power we got was approximately 80 W. Our PV panel gives us approximately 130 W on a very good day.

C. Maximum Power Point Tracking
It is not easy to improve the efficiency of the PV panel and if we want to use better equipments, that is going to increase the price of the installation. That’s why it is easier and cheaper to use the MPPT which stands for Maximum Power Point Tracking. MPPT system is necessary because PV arrays have a non linear voltage-current characteristic with a unique point where the power produced is maximum and this point depends on the heat and irradiation conditions [4]. MPPT Algorithm’s main job is to obtain the maximum power from a PV panel to ensure that the PV panel is always producing power as close to its I-V curve as possible[6].

Figure (04): IV characteristics of a solar panel [5]

Figure (05): PV characteristics of a solar panel [5]

As we can see from the plots, the power depends on the current and voltage characteristics. So in order to get the highest possible power to supply our load we must track the maximum power point by using a special algorithm. There are a lot of different algorithms for the MPPT, most of them are completely different from each other and use different algorithms and have different efficiencies. Examples of such algorithms are Perturb & Observe, Incremental Conductance, Fuzzy Logic Control, Open Voltage Circuit and so on. In this project we will use the Perturb & Observe and Open Voltage Circuit methods to find our MPPT.

You can see the results with no MPPT system in the Table and plot below. First we connected our circuit without using the DC-DC converter and we changed the resistance manually. Here is a table and a plot below and of the PV and IV curves:

Table II: Current, Voltage and Power Values at different load variations P (W) | V (Volt) | I (A) | R (Ω) | 48.7584 | 33.86 | 1.44 | 22 | 83.571 | 31.3 | 2.67 | 11 | 95.31 | 27 | 3.53 | 7.3 | 87.02 | 22.9 | 3.8 | 5.5 | 74.844 | 18.9 | 3.96 | 4.4 | 63.282 | 15.9 | 3.98 | 3.67 | 53.1275 | 13.45 | 3.95 | 3.14 | 47.0842 | 11.86 | 3.97 | 2.74 | 42.4935 | 10.65 | 3.99 | 2.44 |

Figure (06): IV & PV Curves at different load variations
By using the load variation in the load panel, we connected the circuit directly without using the DC-DC converter to notice the radiation and load effects and trying to find the MPPT location. The load was varying from 500 Ω to 0 Ω and the plots were better than we connected the loads manually.

Figure (07): IV & PV Curves at 9 A.M.

We started calculating at 9 A.M. and it was cloudy so the maximum power we got was 52 W and the ISC was approximately 2.1 A

Figure (08): IV & PV Curves at 9 A.M. and 9:30 A.M.
After it became less cloudy the current increased from 2.1 A to 3 A and the power increased 27% to 71W. That shows how a radiation severely affects the power.

Figure (09): IV & PV Curves at 9 A.M. and 9:30 A.M. and 10:45 A.M.

Now that the weather is even less cloudy than it was at 9:30 A.M., the current improved to approximately 3.8 A and power is up to 79 W. Take in consideration that 79 W isn’t the maximum value of the panel. Some days we get a power up to 120 W but when we did the experiment it was cloudy and a little bit dusty.

D. DC-DC Converters
A maximum power point tracking system needs a converter that will control the voltage to obtain the maximum power. There are many types of converters, i.e. Boost, Buck, Buck-Boost, Cuk and SEPIC. In this project, we used buck type converter that steps down the voltage of the PV, Figure (09) shows DC converters in general.

Figure (10): DC Converters General Circuit [7]

Buck Converter:
The buck converter used for stepping down the input voltage. Figure.5 shows the basic circuit of a buck converter. The main component in the circuit is the switch, which can be a MOSFET, BJT or Thyristor. In this project, we used a MOSFET transistor as a switch. The output voltage depends on duty cycle ratio. Figure (11): Basic Circuit of a Buck [9] Converter

Duty Cycle:
The ratio between the input voltages to output voltage is called duty cycle. Duty cycle is important because it controls the switching pulse that will be injected to the MOSFET gate to control the output voltage.

L and C Selection:
In general, there are equations to select inductor and capacitor values. Here are the equations [8] :
L=Vin-Vout(αf)∆I
C=18Lf2∆V Vout α:Duty Cycle f:Switching Frequancy
∆I:Maximum Output Ripple Current
∆V:Maximum Output Ripple Voltage
In this project, we may stick with the available values in the lab, and we can verify their performance experimentally.

Experimental Components:
For the buck converter, we used a variable resistance, inductors, capacitors, power diode and a switch that is a MOSFET (IRF 9130). The next pictures show the components of a buck DC-DC converter and one picture shows the connections:

Figure (12): (On the left) a MOSFET, (on the right) Power Diode

Figure (13): (On the left) a Function Generator, (on the right) an Oscilloscope

Figure (14): Updated Circuit of a Buck Type DC-DC Converter

We had to update our DC-DC circuit by adding two new resistors in series to do the voltage division rule. Feeding the gate a different voltage value than the one used to feed our source is essential for the circuit to work because if we want our circuit to work as a switch we must follow the MOSFETs rule which specifies that our source voltage value must be higher than the gate voltage value. If we want to shut down the circuit, we make the gate value higher than the source value and that’s how we fixed the problem we had in the DC-DC converter.

Figure (15): Connections of the DC-DC Buck Converter

Figure (16): Connection of a Buck Converter
The figures above are the connections of the original DC-DC converter. The connection of the updated DC-DC converter is shown below.

Figure (17): Connection of the Updated DC-DC converter E. Cassy Lab
After implementing the DC/DC converter we, the next step is designing MPPT controller that will take the values of the voltage and current from the panel arrays and apply the logarithms on the inputs according to the method applied to decide the output of the DC/DC converter depending on the duty cycle of the pulse signal that will trigger the MOSFET gate as mentioned before. There were two options for MPPT controller we can use it in the circuit, Microcontroller, and Cassy Lab. We prefer Cassy Lab over the Microcontroller for several reasons. First of all, all the equipments of the DC/DC converter are compatible with the available Cassy Lab equipments. Secondly, using Microcontroller will require delay in the project, because we need to order it and it takes at least one week to be delivered and programming of the Microcontroller will take time due to the high language required, unlike the easy writing formulas and functions in the Cassy Lab.

Figure (18): Example of some functions available in the Cassy Lab [10]

CHAPTER 2: TECHNIQUES
Many maximum power point tracking techniques for photovoltaic systems have been developed to maximize the produced solar energy. In general, there is a specific point on the V-I or V-P curve, named the Maximum Power Point (MPP), at which the PV system operates with maximum efficiency and produces the maximum output power. The location of the MPP is not known, but can be found, either through calculation models or by search algorithms. Maximum Power Point Tracking (MPPT) techniques are desired to preserve the PV array’s operating point at its MPP [12].These techniques are different than each other in many characteristics, involving simplicity, convergence speed, implementation, sensors required, cost and range of effectiveness .We will talk about the different MPPT techniques below in order:

A. Perturb and Observe
P&O is the most famous one from the MPPT algorithm method due to its simplicity and efficiency. P&O algorithm is grounded on the “hill-climbing” attitude that consists of moving the operation point of the PV array in the direction in which power rises. From Figure (19), it can be seen that incrementing (decrementing) the voltage increases (decreases) the power when operating on the left of the MPP and decreases (increases) the power when on the right of the MPP.

Figure (19): Characteristic PV array power curve. [11]

More on P & O method and its algorithm will be discussed in chapter 3.

B. Incremental Conductance
The incremental conductance method is based on the fact that the slope of the PV array power curve in figure (20) is zero at the MPP, positive on the left of the MPP, and negative on the right, as given by

Measurements of the instantaneous PV array voltage and current require two sensors. We can use a microcontroller control, which can easily keep track of previous values of voltage and current and from Figure (20). [13]

Figure (20): Incremental Conductance shown in [12].

C. Open-Circuit Voltage
This method is considered to be one of the best and easiest methods to track the MPPT. It is going to be discussed in details in chapter 4.

D. Short-Circuit Current
Fractional ISC comes from the statistic that under changing the weather conditions, IMPP is approximately linearly related to the ISC of the PV array as shown next.
IMPP ≈ k2ISC
Where k2is proportionality constant. Just like in VOC technique, k2 has to be determined according to the PV array in use. The constant k2 is generally found to be between 0.78 and 0.92 .Measuring ISC during operation is harder than measuring the open voltage circuit. We must use additional switch to the power converter to periodically short the PV array so that ISC can be measured using a current sensor. For all other applications we didn’t mention in the report, you can see Table III, covering the major characteristics of some MPPT techniques.

You can see in next table the different techniques of MPPT.
Table III. Major Characteristics of MPPT Techniques [13]

CHAPTER 3: PERTURBATION AND OBSERVATION METHOD
Theoretical:
The perturbation and observation (P&O) technique for maximum power point tracking (MPPT) algorithm is very commonly used because of its ability to track maximum power point (MPP) under widely varying atmospheric condition.In Perturb and observe (P&O) method, the MPPT algorithm is based on the calculation of the PV power and the power change by sampling both the PV current and voltage. The tracker operates by periodically incrementing or decrementing the solar array voltage. In this method, the sign of the last perturbation and the sign of the last increment in the power are used to decide what the next perturbation should be. If there is an increment in the power, the perturbation should be kept in the same direction and if the power decreases, then the next perturbation should be in the opposite direction. Based on these facts, the algorithm is implemented. The process is repeated until the MPP is reached. Then the operating point oscillates around the MPP. This is summarized in the following table. [4]
Table IV: Summary of P&O algorithm [4] Perturbation | Change in Power | Next Perturbation | Positive | Positive | Positive | Positive | Negative | Negative | Negative | Positive | Negative | Negative | Negative | Positive |

The algorithm works when instantaneous PV array voltage and current are used, as long as sampling occurs only once in each switching cycle. The process is repeated periodically until the MPP is reached. The system then oscillates about the MPP. The oscillation can be minimized by reducing the perturbation step size. The figure below shows the flow chart of P&O technique. [5]

Figure (21): P&O Algorithm Chart [5]

Experimental:
For perturb and observe (P&O) we will measure the voltage and the current from the panel and calculate the power by using P= IxV.

Figure (22): CASSY Lab Connection [14]

After that we are going to use the logarithm of P&O As shown before by Cassy Lab using the condition below.

Figure (23): Condition of Perturb and Observe
Where the variable "delta" take the difference of the last two points of recording. And the program will understand it as true of false function, if it's satisfy the condition the result will be true=1, and if false=0.

Table V: Condition Results of Perturb and Observe n | Delta (P) | Delta( V) | Result | C | 1 | Positive | Positive | True | 1 | 2 | Positive | Negative | False | 0 | 3 | Negative | Positive | False | 0 | 4 | Negative | Negative | True | 1 |

In the next step, we are willing to program the duty cycle function that will increase if the previous condition is true, and decrease if the condition is false.

Figure (24): Duty Cycle Formula
We can see above the variable "n", that will increase one every one step recording, and the other part of the function that have cosine will be zero at true condition because Cos(90) = 0 , and when the condition is false the first part will be zero due to the C=0 and the second part will decrease the duty cycle. Then we plug the Duty Cycle (D) to the output of the function generator with Pulse function (Frequency = 200 Hz, Vp = 5V)

Figure (25): Function Generator Settings in CASSY Lab
Problems:
* The logarithm of P&O depends on {if-then} Statement. Unfortunately, the Cassy Lab only understand the {if} statement without {then}. * The second problem of the Cassy Lab is you cannot use loops without resetting the result every step and this issue lead to resetting the duty cycle every single step. * Using "n" variable will increase in the duty cycle perfectly, but decreasing the duty cycle having a problem due to the increasing of variable "n" every step.

Results:
After taking automatic recording for one day, the duty cycle secedes 100% and reached 250% and this is because of the increasing of the variable "n".
Table VI: Duty Cycle Results

CHAPTER 4: OPEN CIRCUIT VOLTAGE METHOD
Theoretical:
The second method we used in the project was the Open Voltage method, we decided to use a different method to do a comparison between the more than one method. The algorithm of the Open Voltage is much simpler than the Perturb and Observe algorithm where you only need the value of Voc. The equation that we use in this method is:
VMPP = KVOC
Where K is the constant of proportionality. Proportionality depends on the PV array and from experimentation we saw that the best K value is between 0.71 and 0.78 [5]. For this project we chose a constant value of K which is 0.76 (76%). This value is usually fixed and doesn’t vary much with the sudden changes in the environmental conditions [15]. After that you choose a value of the duty cycle that gives you 76% of your open voltage and start the system.

Figure (26): Block diagram of the voltage based MPPT [16]

The disadvantage of this method compared to the Perturb & Observe is that we must be careful when choosing a time interval to sample. If our sampling time interval which is called the sampling period is too long there will be a considerable power loss. Dr. Jawad Ahmad said: “This is because the output voltage of the PV module follows the unchanged reference during one sampling period. Once an MPP is tracked and a step in irradiance occurs between two consecutive samplings, then the new MPP is not calculated until the next sampling of the array voltage. Consequently, the method initially achieves an incorrect MPP instead of the current one” [16].

Experimental:
At first we connected our DC-DC circuit to a function generator, we didn’t connect any capacitor or inductor and just checked the output voltage from the Resistor. The duty cycle value was 76% and the input value was 15V and the output value was approximately 11.5V which is approximately 76% of the input value and it was square shaped like the Duty Cycle shape.

Figure (27): Function Generator for the Duty Cycle

Figure (28): Output Voltage using Oscilloscope

We still couldn’t see the exact values of the output voltage and how the value of the inductor decreased or increased the ripples so we took the duty cycle directly as a constant from the CASSY Lab output and connected it to our DC-DC converter circuit. Then we took the output directly from the resistor without the capacitor and inductor. The frequency was constant at 200 Hz. Our output voltage looked like:

Figure (29): Function Generator in CASSY Lab

Figure (30): Duty Cycle and Output Voltage without capacitor and inductor

As you can see from figure (27), the output voltage (black) was alternating exactly like the duty cycle (red).

After we connected the capacitor and inductor, and with different variables the output voltage looked like:

Figure (31): Duty Cycle and Output Voltage with capacitor and inductor The resistor value was 500 Ω and the inductor value that we chose was 0.06 H and the Capacitor value was 90 µF with a frequency of 200 Hz.

To see the effect of the frequency we changed the value of the frequency to 500 Hz with the same values of Resistor, inductor and capacitor.

Figure (32): Function Generator using CASSY Lab

Figure (33): Duty Cycle and Output Voltage with capacitor and inductor and 500Hz Frequency

The open voltage method follows the concept, we measure 76% of the open voltage method and the voltage we have it will give us the maximum power point at it duty cycle linear relation.

Figure (34): Open Voltage Formula
After this step, we change the duty cycle until the voltage after the buck converter will equal Vr, and we will get power higher than solar reading about 14% - 18%.

Results:
We connected the CASSY Lab to the updated DC-DC converter in figure (). We used the two panels in process and each of them had a specific job. The first panel was just used to calculate the value of the Open Circuit Voltage and directly gives us the VMAX. We used the other panel to turn on our DC-DC converter.

Figure (35): System with MPPT (blue) and without MPPT (red)

The day that we fixed the circuit was a cloudy and rainy day and as you can see from the graph the power that day was low but our Open Circuit Voltage method worked. As you can see, the output power from the MPPT system was higher than the Power of the system without MPPT and the difference between them was between 15% and 20%.

CHAPTER 5: CONCLUSION
After 14 weeks of non-stop work, we finally implemented a full MPPT system and did two methods. We now know the importance of implementing a MPPT system to a PV panel and how the amount of power will increase due to the MPPT system.

We saw how temperature and irradiance variance during the 14 weeks due to natural weather conditions are affecting our power output. We saw the importance of a DC-DC converter which acts as an interface between the load and the solar module.

The main component of a DC-DC converter is the switching device which can be a MOSFET or a BJT. By using the right formulas, we saw how the value of a resistor or an inductor or a capacitor is extremely important for our MPPT system and we saw how a small change of any of these values will change the shape and value of our output.

After all the things we learned and did in this project, we faced some errors with the DC-DC converter and the MPPT controller by using the CASSY Lab Program in the P&O Method. The problem that we faced in the DC-DC converter was the MOSFET and its current rating. The main problem was that it couldn’t handle a high current and if it stays on high current for 30 seconds, our MOSFET will burn. The reliable solution for this problem is to work with an electronics expert to fix this problem.
The Future Work
The scope of this project was simply to create a working prototype of a MPPT system. This system successfully uses the simple P&O algorithm to reach the MPP. Reaching a stable, true MPP at steady state instead of oscillating around this point would improve the system's efficiency and increase reliability. Thus implementing the incremental conductance algorithm is a good choice in continuing this project. Another extension of this project would be to directly power the microcontroller and other circuits from the solar panel instead of from a power supply. Or to incorporate a power supply into the system that draws energy from the solar panel or an energy storage element that is in turn charged by the solar panel. This extension would allow the system to be deployed to remote locations.

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