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

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

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

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)

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.

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

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

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

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

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

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

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!!

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

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

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

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

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

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

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

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