Solar panel array model for UI FESS development

The overall objective of this project is to develop a model of a PV (Photovoltaic) panel array using MATLAB and to then verify that model using hardware. The PV panel array will be used to supply power to a FESS (Flywheel Energy Storage System) that NASA is developing for energy storage on the lunar surface. The solar panel array model is needed for the University of Idaho’s low speed FESS development.

Background
•	NASA is developing FESS for space applications which include Mars colonization; a first step towards Mars colonization is lunar colonization.

•	Lunar colonization requires energy storage to bridge the gap between energy generation and energy demand (load).

•	The University of Idaho has developed a low speed FESS and is developing a high speed FESS.

•	A solar panel array model is needed for use in UI HS FESS development

Design Goal
The equipment needs to be able to handle the harsh environment on the lunar surface where it will experience temperatures. The PV array model must take into consideration the environmental conditions such as irradiance and temperature using the characteristics of a silicon wafer. Things like power output and voltage fluctuation needs to be taken into consideration as the FESS will regulate the voltage on the panel’s output. The model must be as simple as possible without sacrificing accuracy as the PV panel array will be a piece of a larger electro-mechanical system.

How a photovoltaic cell works
A photovoltaic cell is usually a semiconductor device that converts sunlight into electricity by the means of photovoltaic effect. When light falls on a solar cell, the incoming photons can be absorbed, reflected, or passed through it. For a photon to be absorbed by the solar cell, the energy of the photon must be greater than the band gap energy of the cell. The photon is then absorbed to generate pairs of mobile charge carriers (for example, electron and hole) which are then separated by the structure of the device (such as a p–n junction). This produces a potential difference and thus produces electrical current. The photovoltaic effect is shown by various materials. In most of the cases, semiconductor materials (like silicon) in the form of p–n junction are commercially used to produce solar cells.




 * A semiconductor p–n junction can be made to operate as a solar cell. Figure 1 shows the basic structure of a PV cell. When light is incident on the cell, the photons of light generate free electron–hole pairs which are then attracted toward the junction.

Design Specifications
The model should take inputs of temperature and irradiance that it would see on the lunar surface and give an output voltage and current. Temperatures ranging from -243°F (-153°C) to 253°F (123°C) Solar irradiance of about 100 W/m2 DC bus on the FESS typically operates at 24 V

Ideal cell model
In ideal condition, the solar cell is electrically equivalent to a current source in parallel with a diode as shown in Fig. 3a. The light-generated current, also known as photocurrent, is represented as IL, the diode current as ID, and the net current and terminal voltage of solar cell as Icell and Vcell , respectively.

model must be easily adaptable to different size PV panel arrays and different environmental conditions

Includes PV panel array and charge controller

Must be capable with the FESS model

model will be verified using hardware



MPPT Charge Controller
Max Power Point Tracking is an electronic DC-DC converter that optimizes the power supplied by a solar panel

Ensures the panel’s output is at maximum power



CONTROL ALGORITHM
Incremental Conductance（IC） Algorithm of the proposed MPPT technique

Measures voltage and current then adjusts duty cycle to remain at peak power



Project verification
Hardware needed for verification

Prices stated out in budget handout

Solar panel to verify the PV Panel Array model

Maximum Power Point Tracking MPPT Charge Controller to verify charge controller and entire system under load

Solar Panel
The Series and Parallel resistance values Rs and Rp are not given by manufacturer These parameters can be derived using the experimental maximum power Pmex Start by incrementing Rs starting from zero until the calculated maximum power Pmax = Pmex then calculate Rp using Rs



Maximum output power is necessary in determining Rs and Rp from the PV Cell equivalent circuit Pmax can be determined by measuring the output voltage and current using various resistive loads The maximum power can be determined by plotting Pout vs Vout



PV Model Cell
model must be easily adaptable to different size PV panel arrays and different environmental conditions Includes PV panel array and charge controller

Must be capable with the FESS model

model will be verified using hardware



SOLAR PANEL INSTALLATION
3 piece of solar panel in parallel connect with MPPT charge controller, then connected with load.



DETERMINE MAXIMUM POINT
Maximum output power is necessary in determining Rs and Rp for the PV Cell equivalent circuit

Pmax can be determined by measuring the output voltage and current using various resistive loads

The maximum power can be determined by plotting measured Pout vs Vout

Various resistive loads can be obtained using resistor bank from lab



MODELING THE ROVER MPPT
The duty cycle will be determined using the incremental conductance algorithm within a Matlab script

The parameters of the buck boost converter will be determined by measuring the voltage and current waveforms using a resistive load

1.Voltage and current ripple

2.Switching frequency



Testing short circuit current and open circuit voltage
Using pyranometer to test the solar radiation. Using Multimeter to test the short circuit current and open circuit voltage

Testing solar panel connect with load bank
Connect solar panel directly with load bank, Testing the real time radiation and voltage and current in the load bank.

Testing solar panel with MPPT charge controller and load bank
Using pyranometer to test and log the solar radiation. Using the software from MPPT charge controller manufacturer to test the current, voltage, power on load bank, solar panel, and battery.

Data Logging
Rover MPPT includes software to log output power over a long period of time

Lab equipment will be used to record transient information

Pyranometer will be used to take periodic measurements of irradiance

Infrared thermometer will be used to take periodic measurements of temperature

LUNAR TEMPERATURE AND RADIATION
Solar flux on the lunar surface will be much higher than see on the Earth’s surface Peak at 1376 W/m^2

A lunar day is about 30 Earth days

Temperature ranges from -200°C to 100°C in a similar sinusoidal fashion



Project Budget
3 pieces of Solar panel

Company: Backwoods Solar Company Location:Distributor located in Sand Point, ID 295 W Solar Panel Q.PEAK BLK-G4.1 295

Supplies 218 W under normal operating conditions VMPP = 30.3 V IMPP = 7.2 A

Rover Mppt charge controller 40A



Fall 2017 Semester
Develop PV panel array model using MATLAB

Modularize PV panel array model

Order hardware necessary for verification Solar panel

Maximum Power Point Tracking Controller

Spring 2018 Semester
Incorporate Charge Controller into PV panel array model

Specifically MPPT Controller

Verify model using hardware Including IV characteristics as well as running a DC machine and potentially UI’s FESS

Verify Capability with FESS mode

Meeting Minuets
9-12-17

9-19-17

9-26-17

10-3-17

10-10-17

10-17-17

10-24-17

10-31-17

11-7-17

11-28-17

12-5-17

1-21-18

1-29-18

2-12-18

2-18-18

2-21-18

2-26-18

3-5-18

3-21-18

3-27-18

4-2-18

4-23-18

Other Documents
Scope and Notes

Team Contract

Project Snapshot Poster

Design Review

current budget

testing data from MPPT charge controller software

Team Information


FROM LEFT TO RIGHT

{| class="wikitable"


 * style="text-align: center;" | Member
 * style="text-align: center;" | Biography
 * style="text-align: center;" | Discipline
 * style="text-align: center;" | Discipline


 * - align="center"
 * Haotian Wang
 * I am a senior student in electrical engineering at University of Idaho. I am a international student from China, Nanjing, Jiangsu province. I plan on graduating in May 2018, i love NBA and soccer.
 * Electrical Engineering


 * - align="center"
 * Mingyang Xu
 * Mingyang is a Senior in the Electrical Engineering at the University of Idaho. He come from China and is a transfer student from Soochow university. He will graduate in May 2018. He plans on continuing his study in UI as a graduate student.
 * Electrical Engineering


 * - align="center"
 * Sean Daniel
 * I am a senior in Electrical Engineering at the University of Idaho and am interested in working with power electronics and control systems. I plan on graduating in May, 2018 and am looking forward to working on modeling a solar panel array for the UI Flywheel Energy Storage System.
 * Electrical Engineering