Team 20

Could solar energy be harnessed effectively at the College?What application might it have? : 

Could solar energy be harnessed effectively at the College?What application might it have? From left to right: Ryan Cheung, Shravan Karnani, Jessica Beadman, Mr. Drew, Jonas Ladegaard, Abhishek Dhandia, Jayesh Dalani

Solar Energy : 

Solar Energy Advantages - Renewable resource - Take advantage of unused space such as the roof - Non-polluting - Very little maintenance - Save money in the long run - Very easy to install

Solar Energy : 

Solar Energy •Disadvantages - Solar cells/panels, etc can be very expensive - Cannot utilize the energy form the sun at night or stormy, cloudy days, etc.

Different ways of storing solar energy : 

Different ways of storing solar energy Solar energy - light and heat from the Sun that can be collected and coverted into uses such as: - heat, light, hot water, electricity   Photovoltaic Cells Heating a transfer fluid   1)Photovoltaic cells converts the energy of sunlight directly into electricity. 2) Heating a transfer liquid - heating water by the use of solar energy   These two ways of storing solar energy will be the basis of our project and how it can be applied to Sha Tin College.

Experiment 1 -Heating a transfer liquid : 

Experiment 1 -Heating a transfer liquid What we need to find? - Total amount of energy that could be collected from the sunlight   Procedure - What we did?    Measure 200ml of water in a measuring cylinder Pour it into 200 ml beaker Measure temperature of water with temperature probe Wrap the test tube with black plastic bag and use rubber bands to hold it in place Place the wrapped up beaker on the roof top. (5Th floor) Leave the beaker up on the roof for 30 minutes After 30 minutes, unwrap the beaker and record the temperature Switch beakers and starts the experiment for the next 30 minutes (Replace water and re take new water temperature)

Experiment 2 - Photovoltaic cells : 

Experiment 2 - Photovoltaic cells What we need to find?  - The total amount of energy received from the sunlight which could be converted into electricity within a day.   Procedure - What we did? Setting up the circuit: 1)     Wipe the solar cell with a tissue to get the dust of the solar panel in order to reduce limitation. 2)     Connect wires into circuit and check the circuit by send current into it. 3)     Record data every ½ hour, collect readings of current and voltage and calculate the power. Power (watts) = current (amps)  x voltage(volts) 4)     Plot the graph and find the area under the graph. The area under the graph = the energy throughout the day in joules. 5)     Compare it to the energy required for a standard light bulb. It requires 58 joules per second to light it up.

Heating up water to figure out the amount of heat energy received from the sun : 

Heating up water to figure out the amount of heat energy received from the sun Experiment 1

Hypothesis : 

Hypothesis At the start of the day, there will be less sunlight. Less solar radiation=Less heat energy absorbed As the time of day starts to reach mid day, the temperature of the water should increase. More energy can be obtained during the middle of the day After midday, the intensity of sunlight will naturally decrease since the sun starts to set.

Slide 9: 

http://www.weather.gov.hk/publica/tnl/tnl080.pdf

Experiment 1 (Water Heating) - Limitations : 

Experiment 1 (Water Heating) - Limitations Cloud cover More time to do properly Unnatural environment –Air conditioned Infrared rays (Very little in light spectrum) The way we heated the water (Another group can look into)

Experiment 2 (PVC) - limitations : 

Experiment 2 (PVC) - limitations ·Different parts of the roof = different light intensity because of the presence of buildings and other equipment. And because of limited time we could only carry it out in one place.  ·Keeping cost in mind, the school has old and cheap solar panels; this hinders the ability to be effective in absorbing and converting energy.  ·The circuit has contact resistance. This means that if there is a lot of resistance, there will be a lot of heating. And bad contacts make the piece of equipment not work to its full potential.  ·Weather condition differs at different days; some are sunnier compared to others.  ·The incident angle at which the solar panel can affect the amount of power produced.

Results and analysis of Experiment 1 - Solar Water Heating : 

Results and analysis of Experiment 1 - Solar Water Heating Working out the energy received from the sun: Power = Energy / Time Energy = Specific Heat Capacity Specific Heat Capacity = MC∆T M=0.2 KG C=4200 Number of beakers we can fit on the 245.58 beakers per m2 Total Energy (If we put beaker all over the roof) = 7082742.82 Joules= 7082.74 Mega Joules

Table of data for experiment 1 : 

Table of data for experiment 1

Experiment 1 results : 

Experiment 1 results

Problems with experiment 1 : 

Problems with experiment 1 (Metalic) Surface that beaker is placed on is hot Area of the beaker * (Number of beakers the fit on the roof) Need to convert energy to electricity, (such as using the steam to turn a turbine/generator) Initial temperature of water increased

Slide 16: 

Hot Surface

Sustainability : 

Sustainability Solar energy -Renewable resource School already has equipment  Scrap cardboard used to protect equipment Scrap paper used for diagrams

Solar Water Heating : 

Solar Water Heating 10:00 to 14:00 received a total of 7082742.82 joules from the sun.  Total energy received can increase the temperature of 84.32 kg of water by 20 degrees.   P.E. Showers - Hot water - An average person will use 10 gallons of water in an average shower.   10 gallons X 3.78 kgs (one gallon that is.) =37.85 kgs of water in an average showers à84.32 / 37.85  =2.23 showers in 4 hours à 11 hours could heat up 6 showers (a day)   In a year, we can heat 1500 P.E. with the solar panels. The beaker filled with water covered in a black plastic bag

Solar Water Heating (Cont.) : 

Solar Water Heating (Cont.) Other than heating water, we wondered how much electricity we could actually generate from the 4 hours Total energy from the Sun / time  = Power received 7082742.82 / 14400= 491.8571403 Watts (Standard light bulb needs 58 Watts to function) 491.8571403 Watts / 58 Watts  = 8.5 Bulbs This means that in an average day, the sun could power 23.375 light bulbs Some other LIMITATIONS however, could have tampered our results. For example, we used beakers in our experiment. This would not be used for actual solar harnessing The sun’s strength varies from day to day.

Experiment 2 : 

Experiment 2 Using P.V. Cells to measure the amount of solar energy received

Circuit Diagram : 

Circuit Diagram

The Data table : 

The Data table

The graph : 

The graph Area under the graph: 0.30 square units The power produced by one solar panel through out different times of the day Power Time

The number of solar panels that can cover the flat roof area : 

The number of solar panels that can cover the flat roof area The number of solar panels that can cover the flat roof area (9419000/34) cm2 = 277,030 solar panels Total watts produced: 0.30 x 277030 = 83109 watts. 83109 / 58 watts = 1433 bulbs

But the cost…… : 

But the cost…… Cost of installation: 277,030 x HKD 60 = HKD 16,621,800 Electricity cost through out a year in Sha tin college = 957,682

Industrial Solar cell : 

Industrial Solar cell Installation + maintenance fee= 0 Grant by government = HKD 500 000 Cost of one solar panel = 0 The area of solar panel: 10 m2 941.9 meter squared / (10 m2 ) = 95 solar panels

How much energy will they produce? : 

How much energy will they produce? The watts from the solar panel: 95 solar panel x 180 watts = 17100 watts =17100/ 58 watts =2358 bulbs 2358 v/s 1433 2358/20= 118 rooms

CLP : 

CLP CLP unit = 1000 x 60 x 60 J = 3.6 x 10^6 Sha Tin College uses around 39000 units per year. The cost per unit= 84.9 cents They pay every 2 months.

Savings… : 

Savings… Total energy received through out the day (482480000)/3.6 x 10^6 = 136.8 units/day School year: 250 days =250 x 136.8 = 34200 units per year for free 34200 x 0.849 = HKD 29035.8 savings /year

Comparison : 

Comparison In comparison of both experiments is shows great differences in various areas.  -The solar water heating experiment it shows that the energy generated from it supplies electricity to 8.5 light bulbs, where as when using solar cells they generate an extensive yet reasonable amount of electricity which is efficient for our use of electricity that is needed.  -The weight of the instruments used effectively differentiate between one another. The weight of solar panels is much lighter compared to the weight of water. The ability of weight the roof can hold is being tempered with and we would encounter complications that is not financially beneficial for our college.  Also the school does not require much of heated water as it is not a constant necessity for our college.  Converting the energy in the water into electrical energy would not be as efficient as there would be energy losses. This is caused from.... -solar cells have the efficiency of approximately 80-85%, and electricity is more crucial to the college opposed to hot water.

Conclusion : 

Conclusion To conclude this investigation it has come to our attention that we can harness solar energy. Although we need to consider whether it can benefit the school, financially. Concluding we should use solar cells rather than solar water heating as shown in the experiments before, as it is impractical due to the limitations we face:  -Waterproofing the roof; This would be an important factor as damage caused from leakage would be financially ineffective.  -Another factor we would have to comply with would be keeping up with the maintenance solar heating would persist of.  -Also due to the heavy amounts of weight that the tanks hold it would be unreasonable to situate them on the roof as we would fail to follow weight regulations.  Therefore we have chosen to consider solar cells as our superlative way to success with harnessing the solar energy that is being generated. In comparison of both experiments it shows that electricity is used on a regular basis where we will benefit more from the solar panels as it is more efficient in opposed the solar water heating.

Question for next group 4(Starting point for year 12’s) : 

Question for next group 4(Starting point for year 12’s) Should these things be applied? How can they be applied in an effective way e.g. using water as a coolant to boost efficiency or using reflectors? Is it reasonable to use a more efficient solar water heater rather than using solar cells? Is there another way to heat the water in experiment 1? (The way we heated the water had a lot of energy loss)