Ecology lab



|Solar Panel |Team: |

|w/ Sun Tracker | |

Applications

A solar panel is useless without the sun, moreover, the panel must facing the sun in order for it to work. But the sun moves across the sky each day, and every minute that the panel does not directly face the sun, the more energy that is wasted. Roof solar panels are best when the house is facing West/East (figure 1) since ONE side of the house is always basking in sunlight. But for the millions of homes that are not (figure 2), the sun tracks over the peak of the house and can be blocked by that peak. Because of this problem, the task is to build a solar panel rigging system that will track the sun and move the solar panels with a single photocell sensor.

|Figure 1: West/East Facing Houses |Figure 2: North/South Facing Houses |

|[pic] |[pic] |

An example of this exact project can be found:

Lab Setup

There are a few items that need to be set in RoboPro and in general. They are:

1. The kit is required.

2. In RoboPro:

a. Select “Level” in the menu bar, and select “Level 4”

3. Other parts needed:

a. Mounting Plate, pg 4, part #38 251 x 6 (Our Solar Panels!)

b. Photocell, pg 3, part #32 698 x 1

c. Base plate, pg 4, part #35 602 x 1

d. Masking Cap, pg 5, part #36 532 x 1

e. Motor, pg 2, part #32 293 x 1

f. Mini Switch, pg 5, part #37 783 x 3

g. Angle block 30, pg 1, part #31 011

h. Set of wires x 4

Part 1: Solar Panel Collector Rig

The solar panel rig is simple contraption that will:

hold all four of the solar panels together, all facing flat, like a blanket over a bed

Using the “solar panels” (the four mounting plates), assemble them together in the most lightweight rig possible using any parts in the kit. Using any combinations of the flat yellow girders would be a wise decision.

The general rig contains:

contain the photocell that will be used to move the solar panels directly with the sun

Use a motor that will turn the rig (with the solar panels) towards the sun.

1. the solar panel rig you just built.

2. the 30 degree angle block to tilt the panels slightly.

The general rig needs to move around a pivot point in order to follow the sun. You can use either a rope and pulley system, or the chain and gear system. Build the rig that is able to move at least 180 degrees in order to follow the sun. Program the general rig in RoboPro to move the requested 180 degrees.

|Group Questions (Do not write your answers!!!) |

|What system of movement (chain or pulley) did you use? Why? |□ |

|Why does the rig need to move 180 degrees? |□ |

|On your rig, what would be the best placement for your photocell? |□ |

|Instructor Check and Signature |

|Questions Answered | |

|Robot completed and worked | |

Part 2: The kill Switch!!

Safety first!! Whatever happens to your rig, we need a “kill” switch. A kill switch is a switch that when pressed stops the entire program. Think of it as an “emergency stop” switch. Gas stations, machine shops, and lawn mowers all have kill switches. Attach a switch with wires to I1. Create a RoboPro program “solar”. There will be two programs (called threads) running in the same program. This will be part one. Use the picture below (Figure 1) to create your program. But as a twist, DO NOT USE THE SAME ICON as the one circled. Find an alternative.

|Figure 1: Kill switch program |

|[pic] |

|Group Questions (Do not write your answers!!!) |

|Describe how each icon works? |□ |

|[pic] | |

|There are numbers engraved in the switch you used? There is also a diagram. What does the diagram mean? |□ |

|Instructor Check and Signature |

|Questions Answered | |

|Robot completed and worked | |

Part 3: The photocell placement and programming

The photocell is the key to the rig following the sun. But, only when the photocell is COVERED will the rig move to catch up. Using a partition or shade can we accomplish this. Figure 2 shows how the shad will work with two photocells, you only need one.

|Figure 2: The photocell shade |

|[pic] |

|Group Questions (Do not write your answers!!!) |

|Identify the loop in the program. |□ |

|When will this program end? |□ |

|Instructor Check and Signature |

|Questions Answered | |

|Robot completed and worked | |

Part 4: Testing the Photocell

Connect the Photocell and a set of wires to AX on the interface. Without running the program, click on the interface icon, and answer the questions below. Use your hand to simulate the shaded region. Add a new thread to the “solar” program having the rig move ONLY when the photocell reaches an appropriate shaded number. As a hint, you will need a few items:

1. Figure 4

2. A loop that will CONSTANTLY check to see if the photocell is too dark

|Figure 3: Interface test |Figure 4: Photocell hint |

|[pic] |[pic] |

|Group Questions (Do not write your answers!!!) |

|When your thumb is off (bright) what value is being transmitted from the sensor? Use the Interface Test to help you. (Figure 2) |□ |

|Why is the answer to the previous not 0? |□ |

|What is the MAXIMUM value given by the sensor? |□ |

|What is the MINUMUM value given by the sensor? |□ |

|Instructor Check and Signature |

|Questions Answered | |

|Robot completed and worked | |

Part 5: The return

Using the last two switches, when the rig has turned as far west as possible, and the sun is about to set, when it hits the West switch, have it reset BACK to the east (and hit the other “East” switch to stop) for the next morning’s sun.

|Instructor Check and Signature |

|Questions Answered | |

|Robot completed and worked | |

Sources:





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