MEC 440 Senior Design: Solar

Photovoltaic Heat Recovery

Group H Jackie Chen Matthew Stevens

Luis Lituma Xie Zheng

The Problem

Abstract The efficiency of Solar Panels decreases as their

temperature increases, decreasing their overall power output.

The goal of this project is to improve solar photovoltaic panel efficiencies by cooling them when they overheat and recovering thermal energy for future use.

Existing Products Integra Global Solmaks

Clean and cool down the solar panel with working fluid

Existing Products cont’d Solar panels with thermal glued cooling tube

array A flat-plate photovoltaic solar panel, with an array of water-

cooling tubes affixed against the backside.

Existing Products cont’d Thin film PV module with conductive cooling envelope

The cooling mechanism is accomplished through replacement of existing laminate layers between thin film stack layers with a conductive and reflective material, such as copper or aluminum.

Conductive cooling envelope

Product Design Specifications

Core Features: Capacity to cool panels such that they do not exceed

designated temperature limit (45 degrees Celsius). Retrofittable with solar cell modules within the size of

24 x 18 inches. A well insulated outer frame to effectively recover heat

through the working fluid for re-use. An automated control system which actuates the

cooling system after temperatures exceed a designated maximum.

Product Design Specifications Cont’d

Safety Constraints and Design Standards The weight of the solar cell module and cooling system

combined should not exceed a standard uniform dead load pressure of 5 lb/ft2.

The combined system should be as similar in form to that of the standard solar photovoltaic module in terms of shape as possible, to minimize wind exposure. There should be between 3 and 6 inches of clearance between the module and the rooftop surface.

Final ConceptSingle winding rectangular

duct• Advantages

• Allows insulation of fluid ducting, increasing total thermal energy recovered.

• Reduces the wind load.• More ducting surface• Longer duration of contact• Lengthwise pathing

simplifies construction• Disadvantages

• May be moderately heavy and unsuitable.

• Require machining for parts

• Require additional components for centering and clamping.

SOLAR PANEL COOLING SYSTEM ASSEMBLY

SOLAR PANEL COOLING SYSTEM ASSEMBLY

Sub Assembly 1: COOLING CHAMBER ASSEMBLY

Sub Assembly 1: COOLING CHAMBER ASSEMBLY

Sub Assembly 2:Panel Centering Supports

Bill of MaterialsMACHINE PARTS        

PART ASSEMBLY UNIT COST Q TOTALBOTTOM PLATE COOLING CHAMBER $115.21 1 $115.21

WALLS, DIVISIONS COOLING CHAMBER $12.18 9 $109.62TOP CONDUCTING PLATE COOLING CHAMBER $268.38 1 $268.38

LONG CENTERING SUPPORTS PANEL SUPPORT $82.21 2 $164.42SHORT CENTERING SUPPORTS PANEL SUPPORT $5.90 2 $11.80

     SUBTOTAL $669.43

HARDWARE & EPOXY        DESCRIPTION ASSEMBLY UNIT COST Q TOTAL

10-32 x 1"L SCREWS PANEL SUPPORT $1.24 2 $2.48JB WATER-WELD EPOXY COOLING CHAMBER $5.47 8 $43.76

      SUBTOTAL $46.24

TEMPERATURE CONTROL SYSTEM        DESCRIPTION ASSEMBLY UNIT COST Q TOTAL

INTELLI-CIRCUIT CONTROLELR SOLAR PANEL COOLING SYSTEM $189.00 1 $189.00      SUBTOTAL $189.00

Bill of Materials

MATERIAL DESCRIPTION SUBTOTALMACHINE PARTS 669.43

HARDWARE & EPOXY 46.24TEMPERATURE CONTROL SYSTEM 189.00

TOTAL 904.67

FEA using SolidWorks

SOLAR RADIATION IN

𝑇𝑤𝑎𝑡𝑒𝑟 ,𝑖𝑛=15 °𝐶

𝑇 𝑝𝑎𝑛𝑒𝑙=45 °𝐶

𝑇 𝐴𝑀𝐵=22 °𝐶

𝑇𝑤𝑎𝑡𝑒𝑟 ,𝑜𝑢𝑡=25 °𝐶

@ 300𝐺𝑃𝐻

Simulation Assumptions: ·Conditions similar to those in San Diego, CA on an August afternoon·Steady fully developed water flow, entering at 15°C and 300 GPH.·Negligible effects of convection on the panel and cooling system.

Summary of Results:· Panel Temperature reaches a minimum of 42°C after 2 min. of cooling· Panel Temperature will not exceed maximum threshold for 28 min. thereafter· Temperature of bottom surface of copper plate increases with time approachingA maximum of near 42.5C after 10 minutes, indicating heat is in fact being conductedAway from the panel towards the water.· An outlet water temperature of approximately 25°C, an increase of 10°C a result of the panel cooling process.

FABRICATIONCOOLING CHAMBER ASSY

COOLING CHAMBER ASSY

FABRICATIONFINAL ASSY

SOLAR PANELCOOLING SYSTEM ASSY

TESTINGSPECIAL THANKS TO THE ENERGY TECHNOLOGIES LAB STAFF

FOR ALL THEIR SUPPORT

TESTING

TESTING

Testing Results

0 100 200 300 400 500 600 700 8000

10

20

30

40

50

60

f(x) = 1.90749952460193E-07 x³ − 0.000206325083776066 x² + 0.0247332777970039 x + 53.9787581699346

f(x) = 9.20562173087462 ln(x) − 14.0410745132957f(x) = − 1.81030389363721E-05 x² + 0.0464952177452176 x + 24.1753968253968

PANEL SURFACE TEMPERATURE VS. TIME

PANEL TEMPERATURE W/O COOLING

time, t (seconds)

Pane

l Sur

face

Tem

pera

ture

, T (°

C)

Uncooled temperature reaches its maximum at 54.4 CCooled temperature reaches its local minimum at 36.1 C

Uncooled Assembly

Temperature rises 26.1 C from ambient.Power drops by 4.38% to 1.72 Watts.

0 100 200 300 400 500 600 700 800 9001.68

1.7

1.72

1.74

1.76

1.78

1.8

1.8223.9°C

27.6°C

30.3°C

31.1°C

33.6 36.9°C

36.4°C41.9°C

43.3°C

44.2°C

45.3°C

46.9°C

48.3°C

°49.2C

SOLAR PANEL POWER OUTPUT VS. TIME

Time (s)

SOLA

R PA

NEL P

OWER

OUT

PUT,

P (W

)

Cooled Assembly

Temperature drops 16.9 degrees to local min at 37.5 C.

Power output increases by 4% at peak.

0 100 200 300 400 500 600 700 800 9001.64

1.66

1.68

1.7

1.72

1.74

1.76

1.78

1.8

54°C54°C

53°C 52.8°C 52.0°C48°C46°C

42°C38°C 36.7°C

36.4°C 36°C 37°C°38C

SOLAR PANEL POWER OUTPUT VS. TIME

Time (s)

SOLA

R PA

NEL P

OWER

OUT

PUT,

P (W

)

ResultsVerification of existing theory and successful

proof of concept.Successful increase in maximum power output

and efficiency in PV panel.Insufficient retention of heat in working fluid –

increase in about 3 degrees C at most.Weight of completed assembly with water can

meet PDS criteria but creates limit on roof coverage.

POTENTIAL IMPROVEMENTS CONSIDER USING MOLDED THERMOPLASTIC FOR COOLING CHAMBER- This method for manufacturing was originally considered, but was never taken into consideration

taken associated lead times and costs associated with plastic molding processes. Using a molded design would ultimately facilitate both the manufacturing and installation processes.

USE INSULATION WITHIN THE CHAMBER- While the system clearly demonstrates an ability to cool the surface of the solar panel within the

desired range of temperatures, our goal for the outlet temperature of the water for heating was not what initially expected. One obvious culprit can be found in losses through the walls of the cooling chamber. A modification including the addition of insulation would reduce the heat lost through the walls of the cooling system and increase the outlet temperature of the water.

THE ADDITION OF FINS FROM THE BOTTOM SURFACE OF THE COPPER PLATE WHICH EXTEND TOWARDS THE MIDDLE OF THE COOLING CHANNELS

- Another means of increasing the heat transferred to the water is the addition of conductive finned surfaces extending from the copper plate and into the cooling chamber channels. Such fins could also be made of a copper material, or any other suitable conductor.

SPECIAL THANKS TO: PROFESSOR’S GE AND ROSATI

OUR ADVISOR, PROFESSOR DAVID J. JAE-SEOK HWANG

THE SOLAR RACING TEAM

PROFESSOR KEN TESTA, SEAN STOLL, AND GLENN MUSANO