Sustainable Energy Systems Sustainable Energy Systems EngineeringEngineering

Peter GevorkianPeter Gevorkian

Ch 2: Solar Power Generation Ch 2: Solar Power Generation DesignDesign

Brevard Community CollegeBrevard Community College

EST1830EST1830

Bruce HesherBruce Hesher

Other ReferencesOther References

Photovoltaic systems is only a topic for this text. If you Photovoltaic systems is only a topic for this text. If you want more info try:want more info try:

Photovoltaic SystemsPhotovoltaic Systems by Jim Dunlop. This is the text for by Jim Dunlop. This is the text for ETPC2410 Photovoltaic Technology.ETPC2410 Photovoltaic Technology.

Section 690 of the National Electrical Code (NEC)Section 690 of the National Electrical Code (NEC)

www.enphaseenergy.com

www.fsec.ucf.edu/en/consumer/solar_electricity/basics/types_of_pv.htm

Photovoltaic System Photovoltaic System TypesTypes

Utility Interactive (Grid-Tied)Utility Interactive (Grid-Tied): Most common type for : Most common type for residential. Only works when sun is up. Uses the grid residential. Only works when sun is up. Uses the grid to store energy. Used to lower the electric bill.to store energy. Used to lower the electric bill.

Stand-aloneStand-alone: Provides power when grid is down. : Provides power when grid is down. Uses batteries to store energy. Has high cost and Uses batteries to store energy. Has high cost and maintenance. maintenance.

HybridHybrid: Has more than just solar modules as an : Has more than just solar modules as an energy source (wind turbine, generator, etc). energy source (wind turbine, generator, etc). Google Google HOMER.HOMER.DedicatedDedicated: Used as power source for a specific : Used as power source for a specific system. ex: road signs, electric car recharging system. ex: road signs, electric car recharging stations, communications repeaters, water stations, communications repeaters, water pumping. pumping.

Bi-ModalBi-Modal: has features of both Grid-Tied and Stand-alone. More equipment but provides power when utility is out.

Design SkillsDesign Skills Solar power design essentially consists Solar power design essentially consists of electronics and power systems of electronics and power systems engineering, which requires a thorough engineering, which requires a thorough understanding of the electrical understanding of the electrical engineering discipline and the prevailing engineering discipline and the prevailing standards outlined in Article 690 of the standards outlined in Article 690 of the National Electrical Code (NEC).National Electrical Code (NEC).

Designers are only one part of Designers are only one part of the workforce needed for the PV the workforce needed for the PV industry. Installers, Energy industry. Installers, Energy Auditors, System Integrators Auditors, System Integrators (wholesale and retail outlets), (wholesale and retail outlets), manufacturing staff to build manufacturing staff to build equipment, and others are also equipment, and others are also needed. needed.

Functions Systems Functions Systems PerformPerform

Not every system type performs every function. Not every system type performs every function. Utility Interactive systems do not have batteries; Utility Interactive systems do not have batteries; a hybrid system will have multiple energy a hybrid system will have multiple energy sources.sources.

Solar Power System Solar Power System Components and Components and

MaterialsMaterials

note: The text’s use of terminology on p26 is poor.

Sample PV System DiagramsSample PV System DiagramsUtility Interactive systems with battery Utility Interactive systems with battery

backupbackup

Sample PV System DiagramsSample PV System DiagramsUtility Interactive systemUtility Interactive system

Wiring DiagramWiring Diagram(Enphase D380 Utility Interactive System)(Enphase D380 Utility Interactive System)

BatteriesBatteries Not used for most residential grid-tied systems. Used Not used for most residential grid-tied systems. Used in stand-alone systems. Required if power needed in stand-alone systems. Required if power needed when grid is down. when grid is down.

Batteries are expensive and high maintenance. May Batteries are expensive and high maintenance. May have significant permitting requirements. Can also be have significant permitting requirements. Can also be dangerous.dangerous.

Solar batteries are not car batteries. Car battereis are Solar batteries are not car batteries. Car battereis are designed for fast discahrge and slow recharge. Solar designed for fast discahrge and slow recharge. Solar battereis are designed for slow discharge and recharge.battereis are designed for slow discharge and recharge.

Special Solar batteries or deep cycle marine Special Solar batteries or deep cycle marine

batteries are sometimes used. batteries are sometimes used.

Solar batteries often have gel electrolyte.Solar batteries often have gel electrolyte.

Some PV Some PV TerminologyTerminology

MPPTMPPT: Maximum Power Pont Tracking. Automatically adjusting the load : Maximum Power Pont Tracking. Automatically adjusting the load on the array to get the most power out of it. Done by Charge Controller on the array to get the most power out of it. Done by Charge Controller or Inverter.or Inverter.

Net MeteringNet Metering: Metering power taken from and sent to the utility : Metering power taken from and sent to the utility company and being charged or paid for the difference. company and being charged or paid for the difference.

InversionInversion: changing DC to AC.: changing DC to AC.

RectificationRectification: Changing AC to DC.: Changing AC to DC.

StringString: modules connected in series.: modules connected in series.

IslandingIslanding: unintentional energizing of a local section of the grid.: unintentional energizing of a local section of the grid.

AzimuthAzimuth: Angle off from due south.: Angle off from due south.

Tilt AngleTilt Angle: the degree the modules are raised up (lattitude for fixed : the degree the modules are raised up (lattitude for fixed array.array.

Sun HoursSun Hours: Average annual KWH per day that strike a particular : Average annual KWH per day that strike a particular location.location.

AWGAWG: American Wire Guage. Standard table for wire guages, types, and : American Wire Guage. Standard table for wire guages, types, and ratingsratings

DeratingDerating: Adjust design parameters to account for temperature or other : Adjust design parameters to account for temperature or other factors.factors.

Components of a PV Components of a PV SystemSystem

Array: Modules are made of cells connected in series. Stings are made of modules connected in series. Arrays are made of strings connected in parallel in a fuse combiner box.Fuse Combiner box: A weather proof box on the roof with the array that individually fuses each string and combines the wires into a +, - , and ground.DC Disconnect: A DC rated switch between the array and rest of system.PCU: Power Conditioning Unit. Unit that does all or most of the following; MPPT, DC to AC inversion, DC to DC conversion. May include a charge controller.Charge Controller: Unit that uses power from the array to charge the batteries, may also do MPPT.AC Disconnect: Switch between distribution panel and utility meter.BOS: Balance of System. Parts of a PV system other than the major components.

Solar Power System WiringSolar Power System Wiring

Starts with the array and the nameplate on the modules. The Starts with the array and the nameplate on the modules. The nameplate gives several important parameters:nameplate gives several important parameters:

VocVoc: Open Circuit Voltage. The highest voltage the module can : Open Circuit Voltage. The highest voltage the module can produce.produce.

VmpVmp: Max Power Voltage: Max Power Voltage

IscIsc: Short Circuit Current. The maximum current the module can : Short Circuit Current. The maximum current the module can deliver.deliver.

ImpImp: Max Power Current: Max Power Current

Component ConnectionComponent Connection

The Series/Parallel arrangement of the modules The Series/Parallel arrangement of the modules and strings determines the voltage and current of and strings determines the voltage and current of the array. The voltage of the array must meet the the array. The voltage of the array must meet the input requirements of the PCU/Charge controller.input requirements of the PCU/Charge controller.

For best performance the arravoltage should be in For best performance the arravoltage should be in the MPPT range of the Charge controller or PCU.the MPPT range of the Charge controller or PCU.

For safety of people and equipment; all For safety of people and equipment; all component connections need to be done while component connections need to be done while the system in NOT energized. Turn off all the system in NOT energized. Turn off all component and shade the array!component and shade the array!

System MonitoringSystem Monitoring

Most Charge Controllers and PCU’s have monitoring ability. It may be a front panel display and it may be on-line graphical display. “Theres an app for that.”

See http://www.enphaseenergy.com/products/products/enlighten.cfm

System that needs attention?