Do Now: Baltimore Polytechnic Institute receives an average of 150 W/m2 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.] 150 Watts m2 * day Area of football field in m2 1 day Watts x = 150 Watts m2 * day 100 meters * 50 meters 1 1000 W 1 kW day 23250 kW x x = 23250 kW = 23.25 MW!!!

December 4, 2013 Objective: SWBAT understand how photovoltaic cells function and the difference between passive and active solar energy. The students will answer the question –How is solar energy converted for use in a typical home? Active Solar Energy

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?

Active Solar Energy The use of mechanical or electrical systems to convert solar energy into thermal or electrical energy. Heating Power Generation Active Solar Water Heating Systems There are two types of active solar water heating systems: 1. Direct circulation systems Direct-circulation systems use pumps to circulate pressurized potable water directly through the collectors. These systems are appropriate in areas that do not freeze for long periods and do not have hard or acidic water. 2. Indirect circulation systems Indirect-circulation systems pump heat-transfer fluids through collectors. Heat exchangers transfer the heat from the fluid to the potable water. Power Generation Systems There are two main types of active solar power generation systems: 1. Photovoltaic (PV) Systems PV materials and devices convert sunlight into electrical energy, and PV cells are commonly known as solar cells. Photovoltaics can literally be translated as light-electricity. 2. Concentrating Solar Power (CSP) Technologies 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. PV System Solar Tower Dish/Engine System Photovoltaics & Concentrating Solar Power Solar Water Heating

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. Active Solar Water Heating Systems There are two types of active solar water heating systems: 1. Direct circulation systems Direct-circulation systems use pumps to circulate pressurized potable water directly through the collectors. These systems are appropriate in areas that do not freeze for long periods and do not have hard or acidic water. 2. Indirect circulation systems Indirect-circulation systems pump heat-transfer fluids through collectors. Heat exchangers transfer the heat from the fluid to the potable water.

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 Solar Power Generation Systems There are two main types of active solar power generation systems: 1. Photovoltaic (PV) Systems PV materials and devices convert sunlight into electrical energy, and PV cells are commonly known as solar cells. Photovoltaics can literally be translated as light-electricity. 2. Concentrating Solar Power (CSP) Technologies 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.

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! 1. Photovoltaic (PV) Systems PV materials and devices convert sunlight into electrical energy, and PV cells are commonly known as solar cells. Photovoltaics can literally be translated as light-electricity. *Show video on daylighting: “Energy 101- Solar PV” And how engineers make..\Solar Innovator - Alta Devices.mp4 a difference

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 P ower! 2. Concentrating Solar Power (CSP) Technologies 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. *Show video on daylighting: “Energy 101- Concentrating Solar Power”

What’s Coming Up? Next week we will begin Water Power. Test on Solar this Friday.