photovoltaic design and installation
DESCRIPTION
Photovoltaic Design and Installation. Bucknell University Solar Scholars Program. Presenters: Colin Davies ‘08 Eric Fournier ‘08. Outline. Why Renewable Energy? The Science of Photovoltaics System Configurations Principle Design Elements - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/1.jpg)
Photovoltaic Design and Installation
Bucknell University Solar Scholars Program
Presenters:
Colin Davies ‘08
Eric Fournier ‘08
![Page 2: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/2.jpg)
Outline
Why Renewable Energy? The Science of Photovoltaics System Configurations Principle Design Elements The Solar Scholars program at
Bucknell (walking tour)
![Page 3: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/3.jpg)
What’s wrong with this picture?
Pollution from burning fossil fuels leads to an increase in greenhouse gases, acid rain, and the degradation of public health.
In 2005, the U.S. emitted 2,513,609 metric tons of carbon dioxide, 10,340 metric tons of sulfur dioxide, and 3,961 metric tons of nitrogen oxides from its power plants.
![Page 4: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/4.jpg)
40%
85% of our energy consumption is from fossil fuels!
![Page 5: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/5.jpg)
Why Sustainable Energy Matters
The world’s current energy system is built around fossil fuels– Problems:
Fossil fuel reserves are ultimately finiteTwo-thirds of the world' s proven oil reserves are
locating in the Middle-East and North Africa (which can lead to political and economic instability)
![Page 6: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/6.jpg)
Why Sustainable Energy Matters
Detrimental environmental impacts– Extraction (mining operations)– Combustion
Global warming? (could lead to significant changes in the world' s climate system, leading to a rise in sea level and disruption of agriculture and ecosystems)
![Page 7: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/7.jpg)
A Sustainable Energy Future
Develop and deploy renewable energy sources on a much wider scale
Bring down cost of renewable energy Make improvements in the efficiency of energy
conversion, distribution, and use
Three Methods:
- Incentives
- Economy of scale
- Regulation
![Page 8: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/8.jpg)
Making the Change to Renewable Energy
Solar Geothermal Wind Hydroelectric
![Page 9: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/9.jpg)
Today’s Solar Picture
Germany leads solar production (over 4.5 times more then US production) – Japan is 2nd (nearly 3 times more then US production) – this is mainly due to incentives
Financial Incentives– Investment subsidies: cost of installation of a
system is subsidized – Net metering: the electricity utility buys PV
electricity from the producer under a multiyear contract at a guaranteed rate
– Renewable Energy Certificates ("RECs")
![Page 10: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/10.jpg)
Solar in Pennsylvania
Pennsylvania is in fact a leader in renewable energy
Incentives– Local & state grant and loan programs– Tax deductions– REC’s (in 2006: varied from $5 to $90 per MWh,
median about $20)
![Page 11: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/11.jpg)
Harnessing the Sun
Commonly known as solar cells, photovoltaic (PV) devices convert light energy into electrical energy
PV cells are constructed with semiconductor materials, usually silicon-based
The photovoltaic effect is the basic physical process by which a PV cell converts sunlight into electricity– When light shines on a PV cell, it may be
reflected, absorbed, or pass right through. But only the absorbed light generates electricity.
![Page 12: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/12.jpg)
Electricity
![Page 13: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/13.jpg)
Part 2: Learning Objectives
Compare AC and DC electrical current and understand their important differences
Explain the relationship between volts, amps, amp-hours, watts, watt-hours, and kilowatt-hours
Learn about using electrical meters
![Page 14: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/14.jpg)
Electricity Terminology
Electricity = Flowing electrons
Differences in electrical potential create electron flow
Loads harness the kinetic energy of these flowing electrons to do work
Flowing water is a good conceptual tool for understanding
![Page 15: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/15.jpg)
Electricity Terminology
Voltage (E or V) – Unit of electromotive force – Can be thought of as electrical pressure
Amps (I or A)– Rate of electron flow – Electrical current – 1 Amp = 1 coulomb/second = 6.3 x 1018
electrons/second
![Page 16: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/16.jpg)
Electricity Terminology
Resistance (R or Ω) – The opposition of a material to the flow of an
electrical current – Depends on
Material Cross sectional area Length Temperature
![Page 17: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/17.jpg)
Electricity Terminology
Watt (W) are a measure of Power – Unit rate of electrical energy
Amps x Volts = Watts 1 Kilowatt (kW) = 1000 watts
![Page 18: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/18.jpg)
Electricity Terminology
Watt-hour (Wh) is a measure of energy – Unit quantity of electrical energy (consumption
and production) – Watts x hours = Watt-hours
1 Kilowatt-hour (kWh) = 1000 Wh
![Page 19: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/19.jpg)
Power and Energy Calculation
Draw a PV array composed of four 75 watt modules.
What size is the system in watts ?
![Page 20: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/20.jpg)
Electricity Terminology
Amp-hour (Ah) – Quantity of electron flow – Used for battery sizing – Amps x hours = Amp-hours – Amp-hours x Volts = Watt-hours
A 200 Ah Battery delivering 1A will last _____ hours 200 Ah Battery delivering10 A will last _____ hours 100 Ah Battery x 12 V = _____ Wh
![Page 21: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/21.jpg)
Types of Electrical Current
DC = Direct Current – PV panels produce DC– Batteries store DC
AC = Alternating Current – Utility power – Most consumer appliances
use AC
![Page 22: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/22.jpg)
Meters and Testing
Clamp on meter Digital multimeter
Never test battery current using a multimeter!
![Page 23: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/23.jpg)
System Types
![Page 24: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/24.jpg)
Part 1: Learning Objectives
Understand the functions of PV components Identify different system types
![Page 25: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/25.jpg)
Photovoltaic (PV) Terminology
Cell < Module < Panel < Array Battery – stores DC energy Controller – senses battery voltage and
regulates charging Inverter – converts direct current (DC )
energy to alternating current (AC) energy Loads – anything that consumes energy
![Page 26: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/26.jpg)
Systems with DC Loads
![Page 27: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/27.jpg)
DC System Options
Battery backup vs. discontinuous use LVD option in charge controller Load controllers
![Page 28: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/28.jpg)
Systems with AC loads
![Page 29: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/29.jpg)
AC System Options
Combined AC and DC loads Hybrid system with back up generator Grid tied utility interactive system without
batteries Grid tied interactive with battery backup
(why might you need this?)
![Page 30: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/30.jpg)
Grid-Tied System(Without Batteries)
Complexity– Low: Easy to install
(less components)
Grid Interaction– Grid can supplement
power– No power when grid
goes down
![Page 31: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/31.jpg)
Grid-Tied System(With Batteries)
Complexity– High: Due to the
addition of batteries
Grid Interaction– Grid still supplements
power– When grid goes down
batteries supply power to loads (aka battery backup)
![Page 32: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/32.jpg)
PV Modules
![Page 33: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/33.jpg)
Part 3: Learning Objectives
Learn how a PV cell produces electricity from sunlight
Discuss the 3 basic types of PV cell technologies
Understand the effects of cell temperature and solar insolation on PV performance
Gain understanding of module specification Identify the various parts of a module
![Page 34: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/34.jpg)
Solar Cells and the PV Effect
Usually produced with Semi-conductor grade silicon
Doping agents create positive and negative regions
P/N junction results in 0.5 volts per cell Sunlight knocks available electrons loose Wire grid provides a path to direct current
![Page 35: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/35.jpg)
Inside a PV Cell
![Page 36: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/36.jpg)
Available Cell Technologies
Single-crystal or Mono-crystalline Silicon
Polycrystalline or Multi-crystalline Silicon
Thin film
– Ex. Amorphous silicon or Cadmium Telluride
![Page 37: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/37.jpg)
Monocrystalline Silicon Modules
Most efficient commercially available module (11% - 14%)
Most expensive to produce
Circular (square-round) cell creates wasted space on module
![Page 38: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/38.jpg)
Polycrystalline Silicon Modules
Less expensive to make than single crystalline modules
Cells slightly less efficient than a single crystalline (10% - 12%)
Square shape cells fit into module efficiently using the entire space
![Page 39: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/39.jpg)
Amorphous Thin Film
Most inexpensive technology to produce
Metal grid replaced with transparent oxides
Efficiency = 6 – 8 % Can be deposited on
flexible substrates Less susceptible to
shading problems Better performance in low
light conditions that with crystalline modules
![Page 40: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/40.jpg)
Selecting the Correct Module
Practical Criteria – Size – Voltage – Availability – Warranty – Mounting Characteristics – Cost (per watt)
![Page 41: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/41.jpg)
Current-Voltage (I-V) Curve
![Page 42: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/42.jpg)
Voltage Terminology
Nominal Voltage – Ex. A PV panel that is sized to charge a 12 V battery, but
reads higher than 12 V)
Maximum Power Voltage (Vmax / Vmp) – Ex. A PV panel with a 12 V nominal voltage will read 17V-
18V under MPPT conditions)
Open Circuit Voltage (Voc )– This is seen in the early morning, late evening, and while
testing the module)
Standard Test Conditions (STC) – 25 º C (77 º) cell temperature and 1000 W/m2 insolation
![Page 43: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/43.jpg)
Effects of Temperature
As the PV cell temperature increases above 25º C, the module Vmp
decreases by approximately 0.5% per degree C
![Page 44: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/44.jpg)
Effects of Shading/Low Insolation
As insolation decreases amperage decreases while voltage remains roughly constant
![Page 45: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/45.jpg)
Other Issues
Surface temperature can be measured using laser thermometers
Insolation can be measured with a digital pyranometer
Attaching a battery bank to a solar array will decrease power production capacity
![Page 46: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/46.jpg)
PV Wiring
![Page 47: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/47.jpg)
Part 4: Learning Objectives
List the characteristics of series circuits and parallel circuits
Understand wiring of modules and batteries Describe 12V, 24V, and 48V designs
![Page 48: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/48.jpg)
Series Connections
Loads/sources wired in series
– VOLTAGES ARE ADDITIVE – CURRENT IS EQUAL – One interconnection wire is used
between two components (negative connects with positive)
– Combined modules make series string– Leave the series string from a terminal
not used in the series connection
![Page 49: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/49.jpg)
Loads/sources wired in parallel:
– VOLTAGE REMAINS CONSTANT– CURRENTS ARE ADDITIVE – Two interconnection wires are used between two
components (positive to positive and negative to negative)– Leave off of either terminal – Modules exiting to next component can happen at any parallel terminal
Parallel Connections
![Page 50: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/50.jpg)
Quiz Time
If you have 4 12V / 3A panels in an array what would the power output be if that array were wired in series?
What if it were wired in parallel? Is it possible to have a configuration that
would produce 24 V / 6 A? Why?
![Page 51: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/51.jpg)
Dissimilar Modules in Series
Voltage remains additive – If module A is 30V / 6A and module B is 15V / 3A
the resulting voltage will be?
Current taken on the lowest value – For modules A and B wired in series what would
be the current level of the array?
![Page 52: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/52.jpg)
Dissimilar Modules in Parallel
Amperage remains additive – For the same modules A and B what would the
voltage be?
Voltage takes on the lower value.– What would the voltage level of A and B wired in
parallel be?
![Page 53: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/53.jpg)
Shading on Modules
Depends on orientation of internal module circuitry relative to the orientation of the shading.
SHADING can half
or even completely
eliminate the output
of a solar array!
![Page 54: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/54.jpg)
Wiring Introduction
PV installations must be in compliance with the National Electrical Code (NEC)
– Refer to NEC Article 690 (Solar Photovoltaic Systems) for detailed electrical requirements
Discussion points– Wire types, wire sizes– Cables and conduit– Voltage drops– Disconnects– Grounding
![Page 55: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/55.jpg)
Wire Types
Conductor material = copper (most common) Insulation material = thermoplastic (most common)
– THHN: most commonly used is dry, indoor locations– THW, THWN, and TW can be used indoors or for wet
outdoor applications in conduit– UF and USE are good for moist or underground
applications
Wire exposed to sunlight must be classed as sunlight resistant
![Page 56: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/56.jpg)
Color Coding of Wires
Electrical wire insulation is color coded to designate its function and useAlternating Current (AC) Wiring Direct Current (DC) Wiring
Color Application Color Application
Black Ungrounded Hot Red (not NEC req.) Positive
White Grounded Conductor
White Negative or Grounded Conductor
Green or Bare Equipment Ground
Green or Bare Equipment Ground
Red or any other color
Ungrounded Hot
![Page 57: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/57.jpg)
Cables and Conduit
Cable: two or more insulated conductors having an overall covering
– As with typical wire insulation, protective covering on cable is rated for specific uses (resistance to moisture, UV light, heat, chemicals, or abrasion)
Conduit: metal or plastic pipe that contains wires– PVC is a common conduit used– Using too many wires or too large of wires in a given conduit
size can cause overheating and also causes problems when “pulling” wire
![Page 58: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/58.jpg)
Wire Size
Wire size selection based on two criteria:– Ampacity– Voltage drop
Ampacity: current carrying ability of a wire– The larger the wire, the greater its capacity to carry current– Wire size given in terms of American Wire Gauge (AWG)
The higher the gauge number, the smaller the wire Voltage drop: the loss of voltage due to a wire’s
resistance and length– Function of wire gauge, length of wire, and current flow in the
wire
![Page 59: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/59.jpg)
Safety Considerations
Unsafe Wiring– Splices outside the box– Currents in grounding conductors– Indoor rated cable used outdoors– Single conductor cable exposed– “Hot” fuses
Disconnects Overcurrent Protection (Fuses & Breakers)
![Page 60: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/60.jpg)
Safety Equipment
Disconnects– Allow electrical flow to be
physically severed (disconnected) to allow for safe servicing of equipment
Overcurrent Protection– Protect an electrical
circuit from damage caused by overload or short circuit
Fuses Circuit Breakers
![Page 61: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/61.jpg)
Grounding
Limit voltages due to:– Lightning– Power line surges– Unintentional contact with higher voltage lines
Provides a current path for surplus electricity to travel too (earth)
Two types of grounding:– Equipment grounding (attach all exposed metal parts of PV
system to the grounding electrode)– System grounding (at one point attach ground to one current
carrying conductor) DC side of system => Negative to ground AC side of system => Neutral to ground
![Page 62: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/62.jpg)
Batteries
![Page 63: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/63.jpg)
Part 4: Learning Objectives
Battery basics Battery functions Types of batteries Charging/discharging Depth of discharge Battery safety
![Page 64: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/64.jpg)
Batteries in Series and Parallel
Series connections– Builds voltage
Parallel connections – Builds amp-hour capacity
![Page 65: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/65.jpg)
Battery Basics
Battery A device that stores electrical energy (chemical energy to
electrical energy and vice-versa) Capacity
Amount of electrical energy the battery will contain State of Charge (SOC)
Available battery capacity Depth of Discharge (DOD)
Energy taken out of the battery Efficiency
Energy out/Energy in (typically 80-85%)
The Terms:
![Page 66: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/66.jpg)
Functions of a Battery
Storage for the night Storage during cloudy weather Portable power Surge for starting motors
**Due to the expense and inherit inefficiencies of batteries it is recommended that they only be used when absolutely necessary (i.e. in remote locations or as battery backup for grid-tied applications if power failures are common/lengthy)
![Page 67: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/67.jpg)
Batteries: The Details
Primary (single use) Secondary (recharged) Shallow Cycle (20% DOD) Deep Cycle (50-80% DOD)
Types:
Unless lead-acid batteries are charged up to 100%, they will loose capacity over time
Batteries should be equalized on a regular basis
Charging/Discharging:
![Page 68: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/68.jpg)
Battery Capacity
Amps x Hours = Amp-hours (Ah)
Capacity:
100 amps for 1 hour
1 amp for 100 hours
20 amps for 5 hours
Capacity changes with Discharge Rate The higher the discharge rate the lower the capacity and vice versa The higher the temperature the higher the percent of rated capacity
100 Amp-hours =
![Page 69: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/69.jpg)
Rate of Charge or Discharge
Rate = C/T
C = Battery’s rated capacity (Amp-hours)T = The cycle time period (hours)
Maximum recommend charge/discharge rate = C/3 to C/5
![Page 70: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/70.jpg)
Cycle Life vs. Depth of Discharge
Depth Of Discharge (DOD) %
# of Cycles
![Page 71: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/71.jpg)
Battery Safety
Batteries are EXTREMELY DANGEROUS; handle with care!– Keep batteries out of living space, and vent battery
box to the outside– Use a spill containment vessel– Don’t mix batteries (different types or old with new)– Always disconnect batteries, and make sure tools
have insulated handles to prevent short circuiting
![Page 72: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/72.jpg)
Battery Wiring Considerations
Battery wiring leads should leave the battery bank from opposite corners– Ensures equal charging and discharging;
prolongs battery life
Make sure configuration of battery bank allows for proper connections to be easily made
![Page 73: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/73.jpg)
Controllers & Inverters
![Page 74: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/74.jpg)
Part 5: Learning Objectives
Controller basics Controller features Inverter basics Specifying an inverter
![Page 75: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/75.jpg)
Controller Basics
To protect batteries from being overchargedFunction:
Maximum Power Point Tracking– Tracks the peak
power point of the array (can improve power production by 20%)!!
Features:
![Page 76: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/76.jpg)
Additional Controller Features
Voltage Stepdown Controller: compensates for differing voltages between array and batteries (ex. 48V array charging 12V battery)– By using a higher voltage array, smaller wire can be
used from the array to the batteries Temperature Compensation: adjusts the charging of
batteries according to ambient temperature
![Page 77: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/77.jpg)
Other Controller Considerations
When specifying a controller you must consider:– DC input and output voltage– Input and output current– Any optional features you need
Controller redundancy: On a stand-alone system it might be desirable to have more then one controller per array in the event of a failure
![Page 78: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/78.jpg)
Inverter Basics
An electronic device used to convert direct current (DC) electricity into alternating current (AC) electricity
Function:
Efficiency penalty Complexity (read: a component which can fail) Cost!!
Drawbacks:
![Page 79: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/79.jpg)
Specifying an Inverter
What type of system are you designing?– Stand-alone– Stand-alone with back-up source (generator)– Grid-Tied (without batteries)– Grid-Tied (with battery back-up)
Specifics:– AC Output (watts)– Input voltage (based on modules and wiring)– Output voltage (120V/240V residential)– Input current (based on modules and wiring)– Surge Capacity– Efficiency– Weather protection– Metering/programming
![Page 80: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/80.jpg)
Solar Site
![Page 81: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/81.jpg)
Part 6: Learning Objectives
Understand azimuth and altitude Explain magnetic declination Describe proper orientation and tilt angle for
solar collection Describe the concept of “solar window”
![Page 82: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/82.jpg)
Site Selection – Panel Direction
Face south Correct for
magnetic declination
![Page 83: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/83.jpg)
Orientation and Tilt Angle
![Page 84: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/84.jpg)
Sun Chart for 40 degrees N Latitude
![Page 85: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/85.jpg)
Site Selection – Tilt Angle
Year round tilt = latitudeWinter + 15 lat.Summer – 15 lat.
Max performance isachieved when panelsare perpendicular to thesun’s rays
![Page 86: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/86.jpg)
Solar Access
Optimum Solar Window 9 am – 3 pm
Array should have NO SHADING in this window (or longer if possible)
![Page 87: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/87.jpg)
Solar Pathfinder
An essential tool in finding a good site for solar is the Solar Pathfinder
Provides daily, monthly, and yearly solar hours estimates
![Page 88: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/88.jpg)
Practical Determinants for Site Analysis
Loads and time of use Local climate characteristics Distance from power conditioning equipment Accessibility for maintenance Aesthetics
![Page 89: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/89.jpg)
Energy Efficiency
![Page 90: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/90.jpg)
Part 7: Learning Objectives
Identify cost effective electrical load reduction strategies
List problematic loads for PV systems Describe penalties of PV system components Explain phantom loads Evaluate types of lighting; efficiency
comparison
![Page 91: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/91.jpg)
Practical Efficiency Recommendations
For every $1 spent on energy efficiency, you save $3-$5 on system cost
Adopt a load dominated approach – Do it efficiently – Do it another way– Do with less– Do without – Do it using DC power– Do it while the sun shines
![Page 92: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/92.jpg)
Typical Wattage Requirements
Appliance Wattage
Blender 350
TV (25 inch) 130
Washer 1450
Sunfrost Refrigerator (7 hours a day)
refrigerator/freezer (13 hours a day)
112
475
Hair Dryer 1000
Microwave (.5 sq-ft)
Microwave (.8 – 1 sq-ft)
750
1400
![Page 93: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/93.jpg)
Appliances to Avoid
Electric oven or stove Electric space heater Dishwasher with heaters Electric water heater Electric clothes dryer
![Page 94: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/94.jpg)
Improving Energy Efficiency in the Home
Space Heating:– Super insulation– Passive solar design – Wood stoves– Propane– Solar hot water– Radiant Floor/
baseboard– Efficient windows
Domestic hot water heating
– Solar thermal – Propane/natural gas– No electric heaters– On demand hot water
![Page 95: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/95.jpg)
Improving Energy Efficiency in the Home
Kitchen Stoves– Solar cookers – Gas burners- no glow
bar ignition – Microwaves
Washing machines– High efficiency horizontal
axis
Cooling – Ceiling fans – Window shades– Evaporative cooling – Insulation– Trees– Reflective attic cover– Attic fan
![Page 96: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/96.jpg)
Phantom Loads
![Page 97: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/97.jpg)
Phantom Loads
Cost the United States:– $3 Billion / year– 10 power plants – 18 million tons of CO2– More pollution than 6 million cars
TV’s and VCR’s alone cost the US $1 Billion/year in lost electricity
![Page 98: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/98.jpg)
Lighting Efficiency
Factors effecting light efficiency– Type of light– Positioning of lights– Fixture design– Color of ceilings and walls– Placement of switches
![Page 99: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/99.jpg)
Incandescent Lamps
Advantages – Most common– Least expensive– Pleasing light
Disadvantages – Low efficiency – Short life ~ 750 hours
Electricity is conducted through a filament which resists the flow of electricity, heats up, and glows
Efficiency increases as lamp wattage increases
FROM THE POWER PLANT TO YOUR HOME INCANDESCENT BULBS ARE LESS THAN 2%
EFFICIENCT
![Page 100: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/100.jpg)
Fluorescent Bulbs
Les wattage, same amount of lumens Longer life (~10,000 hours) May have difficulty starting in cold
environments Not good for lights that are repeatedly turned
on and off Contain a small amount of mercury
![Page 101: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/101.jpg)
![Page 102: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/102.jpg)
Light Emitting Diode (LED) Lights
Advantages – Extremely efficient – Long life (100,000 hours)– Rugged – No radio frequency
interference
Disadvantages– Expensive (although
prices are decreasing steadily)
– A relatively new technology
![Page 103: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/103.jpg)
Mounting
![Page 104: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/104.jpg)
Part 8: Learning Objectives
Evaluate structural considerations
List hardware requirements
Pros and cons of different mounting techniques
![Page 105: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/105.jpg)
General Considerations
Weather characteristics– Wind intensity– Estimated snowfall
Site characteristics – Corrosive salt water– Animal interference
Human factors– Vandalism – Theft protection– Aesthetics
![Page 106: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/106.jpg)
Basic Mounting Options
Fixed– Roof, ground, pole– Integrated
Tracking– Pole (active & passive)
![Page 107: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/107.jpg)
Pole Mount Considerations
Ask manufacturer for wind loading specification for your array– Pole size– Amount of concrete– Etc.
Array can be in close proximity to the house without penetrations to roof structure
![Page 108: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/108.jpg)
Tracking Considerations
Can increase system performance by: – 15% in winter months– 40% in summer months
Adds additional costs to the array
![Page 109: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/109.jpg)
Passive Vs. Active
Passive:– Have no motors, controls, or gears– Use the changing weight of a gaseous refrigerant
within a sealed frame member to track the sun
Active:– Linear actuator motors controlled by sensors
follow the sun throughout the day
![Page 110: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/110.jpg)
Roof Mount Considerations
Penetrate the roof as little as possible Weatherproof all holes to prevent leaks
– May require the aid of a professional roofer Re-roof before putting modules up Ballasted roof mounts work on certain roofs Leave 4-6” airspace between roof and
modules On sloped roofs, fasten mounts to rafters not
decking
![Page 111: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/111.jpg)
Building Integrated PV
![Page 112: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/112.jpg)
Ready for a field tour?
Questions?
If you are interested in anything you have seen today and would like to get involved, please contact any member of the Solar Scholars team:
Colin Davies, Eric Fournier, or Jess Scott (cjdavies, efournie, jpscott)
![Page 113: Photovoltaic Design and Installation](https://reader035.vdocument.in/reader035/viewer/2022062322/56814577550346895db24819/html5/thumbnails/113.jpg)
The END
Thank you for participating in this lecture series
Now lets go out into the field and take a look at the systems that we have already installed.