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Energy and SustainabilitySL E-101

DC Electricity 101

Basic Electrical Energy

Voltage = volts = pressureAmps = current = flowPower = Volts x Amps = Watts=Joules/secEnergy = Power x Time = Watt-hours

Electricity

Electricity is an energy carrier – it can be thought of as a flow of electrons in a wire although it can take many forms

Water Analogy

Volts(pressure)

Amps(flow)

Electricity: Energy and Power

Power: Rate of energy production or consumption Watt (joule/second) Volts x Amps (pressure x flow)

Energy: Total amount produced or consumed JoulesWatt-hoursPower x time

Electricity: Power

Power: Watt (joule/second)Kilowatt = 1000 watts Volts x amps

A watt is a pretty small unit - it takes 1000 of them to run your toaster. A kilowatt is 1000 watts.

Volts

Amps

Electricity: Energy

Energy: Watt-hours (joules)Kilowatt-hour= 1 kw for 1 hour Volts x amps x time

Volts

Amps

A watt-hour is a pretty small unit - it takes 50 of them to make your toast. A kilowatt-hour is 1000 watt-hours. A typical utility-connected family uses about 1000 kilowatt-hours per month of electrical energy.

Electricity: Conversions

One watt-hour = 3.41 btu

One kilowatt-hour = 3410 btu

Solar electric design example

Electrical Drawing Symbols

Capacitance in farads

Inductance in henrys

Resistance in Ohms

Voltage Source

Current Source

Ohm’s Law

V=Voltage = VoltageR=resistance = ohms I = Current = amps

V=IRV/I = RV/R=I

Power and Energy in Electric Circuits

Power = VI = watts1000 watts = 1 kilowatt

Energy = power x time

Series and Parallel

Is Futile

House wiring diagram

Electrical Circuits

Reading Electrical Circuit Diagrams