Wiring of the Photovoltaic System

Our team looked into the wiring of the system and formulated a table consisting of the different connections such as PV to CC, CC to Battery etc. The table consists of fields such as Connector type, connector color, wire gauge, wire type, wire color, wire length and cost.

Connection block diagram and Final 3D schematic

The 3D schematic was developed using Google SketchUp which included a potential orientation of the panels. Due to the limitations in the size of the cart and the weight of each panel, the only viable option was to place the panels horizontally. It was decided that two light sources, each capable of giving out 89000 lumens, would be directed from above utilizing separate stands.

Although initially it was decided to use just two digital ammeters and voltmeters at the charge controller and DC end of the inverter, later it was deduced that having more measuring devices would enhance the learning experience of students. Although this would incur an additional investment, this would not be that significant due to the low cost of these devices. Moreover, the type of wiring that will be incorporated in the system and methodology of implementing the connections to the various components were discussed.

Block Diagram with Electrical Connections

Final Version of 3D Schematic

Photovoltaic System: 3D Schematic

Our design team utilized Google SketchUp 3D CAD software to model our design in real space. Google SketchUp is a free CAD software that several of our team members had previous experience with.  We used the dimensions found on the data sheets of all our components to create the 3D model to scale. This was helpful to visual our project and determine how to mount the solar panels, where to run wire conduits, and the layout of all the devices.  The following figure shows a general overview of our design setup and how it would look in a classroom setting.

The next figure show the bottom shelf with the battery, charge controller, and inverter on it.

The next two figures show the middle shelf that contains the dc load, meter displays, and a 6 plug power strip.  An AC/DC 10Vdc inverter is plugged in and connected to the two bus bars used to supply power to the meters.  Also two 600W dimmer switches will be plugged into the power strip. The dimmer switches will be between the power strip and light stands and provide a means to vary the light intensity to the solar panels. The power strip is rated at 15A and the two light stands will require I_LIGHT = 5.5A at full load each.  Each meter operates at I_METER < 60mA and there are currently 8 meters for a total of I_METERS = 0.48A.  The total current required from the power strip is I_PS = 11.5A which is well under the rated value of 15A.  The power strip has a 6ft cord that plugs into a standard 120Vac wall outlet.

The top shelf shown below supports the frame structure that will house the four 55W solar panels.  

Progress Update

Our team has been discussing, finalizing and updating the different components that we will be using to make our system. We got to see the solar panel that we will be using and realized that the panel dimensions and weight deviated from our original estimations by a large amount. Therefore, we will need to come with a different way of mounting the panels on the cart such that we can easily fit the four panels on the cart along with the mountable light source we are planning to use.

For the light source, we decided to use a 600 Watt High-pressure sodium light bulb mounted on a fixture.

• 600 Watt
• 89,000 Lumens
• Covers a 6' x6' area

From the image below we can estimate the approximate coverage area of the bulb attached to a fixture.

Preliminary 3D schematic: Experiment with orientation of Panels

We started working on the 3D schematic in order to experiment with the appropriate orientation of the panels.

 Shown below is a preliminary version of the 3D schematic using Google SketchUp.

Preliminary Version of 3D Schematic

Budget

Hardware Expenses
Equipment	Quantity	Price/Unit ($)	Sub Total ($)
SunWize, 55 W Polycrystalline Solar Panel	4	235.00	940.00
Morningstar, Charge Controller	1	211.00	211.00
Universal Power, Sealed Lead Acid Battery	1	109.61	105.00
Morningstar, 300W Sine Wave Inverter	1	225.00	225.00
BK Precision, 300W Programmable DC Electronic Load	1	1,095	1,095.00
Suntek Store, DC Digital Ammeter	3	12.08	36.24
Suntek Store, DC Digital Voltmeter	3	7.19	21.57
AC Digital Ammeter	1		0.00
AC Digital Voltmeter	1		0.00
600 W Dimmer Switches	2	32.95	65.90
PlanetLights, 600 W Light Source	2	25.25	50.50
Light Fixture with Ballast	2	205.95	411.90
Light Stands	2	47.99	95.98
Northern Industrial, Service Cart	1	134.99	134.99
Tripp Lite, 15 A Power Strip	2	11.99	23.98
Single Conductor Copper Wire - Red (100 ft)	1	17.85	17.85
Single Conductor Copper Wire - Black (100 ft)	1	14.21	14.21
Single Conductor Copper Wire - Gray (100 ft)	1	15.81	15.81
AC/DC 10 V Power Adapter	1	25.07	25.07
Sea Dog, Bus Bar	2	10.98	21.96
GE, 30 W Light Bulbs	5	4.99	24.95
Bulbs Fixture	1	6.90	6.90
Support Frame - Angle 6061-T6 Aluminum, Extruded	210	0.09	18.9
Support Underside - 6061-T6511 Aluminum, Extruded	105	0.2	21.00
Support Legs - Square. Tube 6063-T52 Aluminum	25	0.13	3.25
		Total	3,586.96

Preliminary Product Description: Solar Energy System

Preliminary Product Description

ECEP 490 Group 5

Product Description

Our design group aims to develop a low cost solar energy demonstration system for middle or high schools. The photovoltaic (PV) system we develop will display voltage and current of key equipment so that students can observe equipment response to changing solar conditions like light intensity and shading. Furthermore, the DC and AC load levels will be variable so that students can observe system response to changing loads. Some of the constraints for our design will be low cost, minimum storage, insulated cover for safety of students, and a mobile cart for easy movement of the entire system. The main features include adjustable light source and load.

Learning Goals

The PV demonstration cart will focus on:

•  Brief high level description of PV system component functions
•   How light intensity effects PV system performance and output
• Shading effects on PV system performance and output
•  Effect of varying load level and battery interaction
•  Concept of Inversion

 System Graphics

The following diagram depicts the single line diagram of the PV system. 

The next figure depicts a block diagram of the PV system.

Component Descriptions

Solar Panel

Type: SunWize SW-S55P 55 Watt Polycrystalline Solar Panel

Charge Controller

Type: Morningstar SunSaver MPPT Solar Controller with maximum power point tracking

Inverter

Type: Morningstar SureSine Pure Sine Wave 300 Watt Inverter

DC Load

Type: BK Precision 8500 300 Watt Programmable DC Electronic Load 

Battery

Type: UPG UB12500 AGM Deep Cycle 12 Volt 50 Ah Battery

Light Source

• Sunmaster MH 1000 Watt, 100000 Lumens.
• Buld Life: 9,000 hours
• Cost $93.95
• Number of bulbs we will use: 1

Digital Ammeter/Voltmeter

•  DC 50A Blue LCD Digital Ammeter and Shunt
• Comes with connecting wire and 50A 75m Vshunt
• Low Power Consumption
• Measuring Input Range: DC 50A
• Working Power Range: DC 6V to 15V
• Meter Dimensions(LxWxH): Approx: 7.2 x 3.6 x 2.5cm (2.9 x 1.4 x 1 inch)
• Shunt Dimensions(LxWxH): Approx: 12 x 2.5 x 1.8cm (4.7 x 1 x 0.7 inch)
• Cost: $12.08

• Mini DC 99.9V Blue LED Digital Panel Meter Voltmeter
• 3 digital bright LED, easy to read the digits
• Power Supply: DC 6V to 15V
• Type: Blue LED
• Measuring Range: 0 -99.9V
• It's easy to install, ideal for DIY
• Safe to use
• Accuracy: ± 0.2%
• Resolution: 0.1V
• Cutout Dimensions: Approx. 38mm (L) x 20mm (W) (1.5 x 0.8 inch)
• Voltmeter Dimensions: Approx. 45(L) x 25(W) x 20(H)mm (1.8 x 1 x 0.8 inch)
• Cable Length: Approx. 20 cm(8 inch)
• Cost: $7.19

Mobile Cart

•  Northern Industrial Structural Foam Service Cart
• Material Type: Structural foam
• Capacity: 500 lbs
• Shelves: 3
• Shelf Capacity: 165 lbs
•  Dimensions W x D x H(in) : 26 x 38 x 33 5/16
• Cost: $144.99

Activities

 Varying the load is one of the activities students can perform to interact and learn about the PV system.  The load can be adjusted by using the DC Electronic Load to adjust DC load and a small multi-speed fan, ac light bulb bank with switches, or some other common variable AC load provided by the demonstrator to change AC load.  The light source can be varied by students by using a dimmer switch commonly used to adjust house lighting to vary the intensity of light.