1. Do Now: Baltimore Polytechnic Institute receives an average of 150 W/m 2 every day during the month of January. How many kW of solar energy land on our football field per day in January?[ Explain your reasoning and show your work.] 23250 kW = 23.25 MW!!! 150 Watts m 2 * day Area of football field in m 2 1day Watts =x 150 Watts m 2 * day 100 meters * 50 meters 11000 W 1 kW day 750 kW =xx

2. Active Solar Energy

3. Essential Questions  What is active solar energy and how can it be used?  How do solar cells work?  How is electricity generated from solar energy transformed for use in the home?

4. Active Solar Energy The use of mechanical or electrical systems to convert solar energy into thermal or electrical energy.  Heating  Power Generation Solar Water HeatingPhotovoltaics & Concentrating Solar Power PV SystemSolar TowerDish/Engine System

5. Active Solar Water Heating:  Direct Circulation Systems  Pumps move water through solar collectors to warm and then back into a tank for home use; a controller monitors water temperature and turns the pump on/off  Indirect Circulation Systems  Pumps move water through solar collectors to warm and then into a heat exchanger to warm up the home’s water tank; a controller monitors water temperature and turns the pump on/off; there is an additional boiler in case more heat is required.

6. Active Solar Power Generation:  Photovoltaic Systems  Light is turned directly into electricity  Concentrating Solar Power Systems  Focused light from the sun either heats steam to run turbines or is converted to thermal energy to run heat engines

7. Active Solar Power: Photovoltaics  Photovoltaics (PV) are materials that convert sunlight into electrical energy; Edmond Becquerel discovered the PV effect in 1839 and the first practical solar cells were created in Bell Labs in 1954. Let’s watch a video on Photovoltaics!

8. Active Solar Power: CSP  CSP technologies use mirrors to reflect and concentrate sunlight onto receivers that collect solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine that drives a generator. Let’s watch a video on Concentrating Solar Power!

9. What’s Coming Up?  Exam Review this week and Exam II on Tuesday 1/15. It will be with Mr. Borah in Room 233.