1. Photovoltaic Systems Engineering Session 07 Photovoltaic Systems:
SEC598S19
Photovoltaic Systems Engineering
Session 07
Photovoltaic Systems:
Technology and Policies
January 30, 2019

2. Session 07 content PV Technology PV Policy Overview Solar Resource
Scales
Components
PV Policy
Examples

3. Energy and Power Optical Energy is the energy contained in light
Chemical Energy is energy stored in atomic bonds, and in the motion or separation of ionic charges.
Mechanical Energy is the energy in moving or displaced objects at both microscopic and macroscopic scales.
Thermal Energy refers to the energy associated with heat and its transfer

4. A Quick Review of Energy and Power
Electrical Energy is the energy contained in electrons and other charged particles; Electrical Power is the rate at which electrical energy is delivered to an “electrical load”
Electrical Power is calculated by multiplying the Electrical Current and the Electrical Voltage in the electrical device
Current is a measure of the flow of electrons (amperes)
Voltage is a measure of the potential energy (volts)

5. But it can be converted from one form to another
Energy and Power
Energy is “conserved”
It is neither created nor destroyed.
The expression, “The solar module created 100 joules of energy” is technically incorrect
But it can be converted from one form to another
The expression, “The solar module converted 100 joules of optical energy into 20 joules of electrical energy and 80 joules of thermal energy (heat)” is technically correct.

6. PV System: Definition
A photovoltaic system (or PV system) is an engineered system that carries out these operations:
Absorption of incident solar radiation
Conversion of the absorbed solar energy to DC electrical energy
Controlled transfer of the DC electrical energy to a storage device (such as an array of batteries) OR
Controlled inversion of the DC electrical energy to AC electrical energy
Controlled transfer of the electrical energy to electrical loads or to the electrical grid

7. PV System Configuration
A simplified version of a “grid-tied”system
that inverts the DC electrical energy to AC
electrical energy and transmits that energy to
the grid

8. The Solar Resource – altitude and azimuth
Markvart, Solar Electricity, Fig 2.7b

9. The Solar Resource – altitude vs azimuth
Häberlin, Photovoltaics, Fig 2.5

10. The Solar Resource – atmospheric effects
The Solar Constant =
1367 W/m2
The Solar Insolation =
1000 W/m2

11. The Solar Resource – the sun’s output
Peak Solar Hours (PSH)
GAM1.5 = 1000 W/m2
Messenger & Ventre, Fig 2.3

12. PV System Components - Solar Cells
The electrical “device” that converts optical energy to electrical energy is the Solar Cell, a semiconductor device invented in 1954 at Bell Telephone Laboratories by Russell Ohl:
The vast majority of solar cells are made from silicon. And this is remarkable good fortune, since silicon is the third most abundant element on the earth’s surface!!

13. Solar Energy Conversion
There is a relation between the current and the voltage of a solar cell:
Increasing
light

14. Block diagram of two source circuit PV system
Grid-Tied PV System
Block diagram of two source circuit PV system

15. PV Systems Residential Scale Non-residential Scale Utility Scale
Self-consumption
Power export
Peak shaving
Self-consumption
Power export
Direct power export to the grid
1-10kW
10-500kW
1-500MW

16. PV System Configurations
Block diagram of solar+storage system (dc)

17. What has fueled this growth?
Technological Factors
Silicon solar cells and modules
Inexhaustible input power at zero cost
Societal Factors
Concerns about fossil fuel and nuclear power plants
An increasing awareness of sustainability issues
Economic Factors
Steady reduction in cost of PV systems
Favorable government policies and business climate

18. Types of Policies Market Preparation Policies Market Creation Policies
Interconnection Standards
Net Metering or Feed-in Tariffs
Solar Rights policies
Market Creation Policies
Renewable Portfolio Standards (RPS)
Solar Carve-out requirements
Market Expansion Policies
Policies that create financial incentives
Policies that enable financing options
Lighting the Way,
Environment Arizona,
September, 2015

19. Impact of Market Preparation Policies, EA-Lighting the Way
Types of Policies
Impact of Market Preparation Policies, EA-Lighting the Way

20. Types of Policies - Arizona
Market Preparation Policies
Net Metering – Reduces payback period
Market Creation Policies
Solar Carve-out requirements – SRECs belong to Utilities
Market Expansion Policies
Policies that create financial incentives
Utility Rebates – 50%
Investment Tax Credit – 30%
Policies that enable financing options
Solar Leases – No upfront costs