Solar panel array model for UI FESS development

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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.

Solar Panel Array Model for UI FESS Development
Team Name Solar FESS
Clients Brian Peterson
Sponsors NASA ISGIO and ECE department
Tech Advisor Dr. Herb Hess
Instructor Dr. Feng Li
Duration Fall 2017 - Spring 2018
Team member Haotian Wang, Mingyang Xu, Sean Daniel

Problem Definition[edit]


• 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[edit]

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.

Project Learning[edit]

How a photovoltaic cell works[edit]

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 .

Fig.1 PV cell structure Villalva et al.

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.

Different parameter models of solar cell[edit]

Parameters Symbol(Unit)
Maximum power rating Pmax(Wp)
Rated current Impp(A)
Rated voltage Vmpp(V)

Short-circuit current Isc(A)
Open-circuit voltage Voc(V)

Normal operating cell temperature NOCT(°C)
Temperature coefficient: short-circuit current (A/°C)
Temperature coefficient: open-circuit voltage V (°C)

Design Specifications[edit]

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[edit]

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

single ideal cell mode

MPPT Charge Controller[edit]

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

MPPT System

Project Design[edit]

PV Model Cell[edit]

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

PV model cell


Incremental Conductance(IC) Algorithm of the proposed MPPT technique

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

IC Algorithm for MPPT

P-T P-V diagram for solar cell model[edit]

P-T diagram[edit]

P-T diagram for solar cell

Solar Irradiance

Measured using a pyranometer

Units: W/m2


Measured using an infrared thermometer

Units: Kelvin = 1°C + 273.15

P-V diagram[edit]

P-V diagram for solar cell

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

Project schedule[edit]

Fall 2017 Semester[edit]

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[edit]

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

Document Archieve[edit]

Meeting Minuets[edit]












Other Documents[edit]

Scope and Notes

Team Contract

Project Snapshot Poster

Design Review


  • Altermatt, P. P. (2011). Models for numerical device simulations of crystalline silicon solar cells–a review. Journal of Computational Electronics, 10(3), 314–330. doi:10.1007/s10825-011-0367-6.
  • Archer, M. D., & Hill, R. (2001). Clean electricity from photovoltaics. London: Imperial College Press.
  • Bal, S., Anurag, A. & Babu, B.C. (2012). Comparative analysis of mathematical modeling of photovoltaic (pv) array. In India conference (INDICON), 2012 Annual IEEE (pp. 269–274).
  • Bendib, B., Belmili, H., & Krim, F. (2015). A survey of the most used MPPT methods: Conventional and advanced algorithms applied for photovoltaic systems. Renewable and Sustainable Energy Reviews, 45, 637–648. doi:10.1016/j.rser.2015.02.009.
  • Brano, V. L., Orioli, A., & Ciulla, G. (2012). On the experimental validation of an improved five-parameter model for silicon photovoltaic modules. Solar Energy Materials & SolarCells, 105, 27–39.

Team Information[edit]



Member Biography Discipline
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
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
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