Shade Webinar 25 Mar 09

Shade Measurement Topics • Site analysis considerations – Impacts of shading – Tilt/Orientation/Weather – Terminology

• Using the SunEye – Tricks and shortcuts – Common problems and solutions – State rebate requirements

• Resources, Questions and Answers

Shading and Site analysis for solar energy systems

PV System Life Cycle

Preliminary assessment

Site survey

Final design

Startup

Preliminary design

Installation planning

Performance Verification

Proposal

Installation

Maintenance

Contract

Checkout

Service

San Diego insolation

Solar Resource Terms • Insolation. Incident Solar Radiation, kWh/m2 • Solar Access. Insolation compared to no shading, in field of view of the panel. • Tilt and Orientation Factor (TOF). TOF is the solar insolation at the actual tilt and orientation divided by the insolation at the optimum tilt and orientation, expressed in percent. • Total Solar Resource Fraction (TSRF). TSRF is the ratio of insolation available accounting for both shading and TOF, compared to the total insolation available at a given location at the optimum tilt and orientation and with no shading. TSRF is also expressed in percent, according to the following equation: TSRF = Solar Access * TOF.

Solar Resource Terms Optimum Annual Insolation

TOF Solar Access Loss due to shading

TSRF

Loss due to suboptimal tilt/azimuth

Solar Resource Example Optimum Annual Insolation

TOF

Solar Access Loss due to shading

Good Solar Access means little shade, but not necessarily the best solar production.

TSRF

Loss due to suboptimal tilt/azimuth

Shading: a little bit goes a long way

100

% Production 50

Best case Real world?

50 % Shading

Actual performance depends on: • Modules ―bypass‖ • Panel configuration • #strings affected

100

Shading: a little bit goes a long way 100%

73%

Business Card covering half of one cell

Shade mitigation strategies • Optimize Shade-Free production – Avoid shade whenever possible – Find the best location for the desired season/time-of-day

• Tree removal – Reduce shade – Minimize debris

• For PV systems – Use best string configuration and placement – Select best panel/inverter type

Shade mitigation example

Shade Avoidance Example Ridge

Layout

Tree

West string

~South

East string

Chimney

Relocated Panels

Solar Energy Quiz What’s wrong with this picture?

• Panel separation should be 2-4 times height • Complex mounting, provides small benefit

Obstruction Distance, Height, Elevation

H/D = TAN ( r=

r)

TAN-1( (H/D)

• D/H as high as possible • D/H > 2 is California Minimal Shading ~26 degrees • D/H > 3+ is ―shade free 9-3‖

Example sun path

Max access

Reduced access

Panel No access

Sun Path

Sun Path example

Hemisphere view (Skyline)

Using the Solmetric SunEyeTM

Copyright Solmetric Corporation, 2008

Steps for measuring solar access Bubble Level

1. Point south* 2. Hold Level 3. Press the button

* Point south in the northern hemisphere; point north in the southern hemisphere.

Compass

Live Measurement example • ―Sky Simulator‖ facilitates indoor use (demos and training) • Small tree toward the east; larger tree toward the west Example azimuth=150º; tilt=30º

SunEye position Always: Level, toward magnetic South

SunEye Example Roof line

SunEye Example

Roof line

Navigation • Use the touchscreen – Designed to work with finger, no need for stylus – Fingernail works best

• Use the 5-way nav button to: – – – –

bring up menu navigate menu snap skylines delete or recapture skylines

Text Entry • select alphabetical or QWERTY keyboard • To clear text or move cursor, click in the text box area • SunEye predicts words being typed, click on word to select

Create a Session 1. > Session > new… 2. Enter Session Name, and note (optional) 3. Enter location 1. Select nearest major city 2. …or, manually enter Latitude and Longitude 3. …or, use SunEye GPS to obtain exact geographical coordinates

Azimuth and Compass Heading •

Enter panel or roof azimuth (ie compass heading) as magnetic heading or true heading – Azimuth displayed in sunpath screen is always true heading – Click on underlined tilt or azimuth to change

•

Always orient the suneye toward magnetic south regardless of panel azimuth or roof orientation – The SunEye automatically accounts for magnetic declination

Skyline View Skyline Note (optional)

Month and time of day labels Annual sun paths superimposed on Skyline Solar Access summary

Tilt and Azimuth

Monthly View

• View the solar access as monthly, seasonal, or annual data • Display average solar access for multiple skyline readings

TOF/TSRF display • Solar Resources • TMY3 weather models • Tilt-Orientation-Factor %, compared to optimum • Total Solar Resource Fraction, %, • TSRF = TOF times solar access.

―Obstruction Elevation‖ View • Obstruction Elevation Angle vs. Azimuth • Max (or average) elevation in azimuth windows

Editing Open Sky and Obstructions • • •

• •

• •

Correct automatic open sky/obstruction detection Simulates obstruction removal such as trimming trees Click paintbush icon a second time to cycle paintbrush between large (two squares in icon) and small (one square in icon) Hold brush by outer square so brush is viewable while painitng Zoom out and select large brush to cover larger areas faster Zoom in and select small brush to do detailed work Pan in the image by selcting the hand icon and clicking and dragging in the image—fingernail works best

See the effect of new construction by filling in between storey poles Storey poles

Fill in where future building will be

See changes in Solar Access

Battery • View battery level: –

>

> about Solmetric SunEye…

• Store SunEye attached to AC power – If not plugged into AC power, battery will discharge over about a week even when SunEye is left off

• SunEye will charge via USB, however the computer must be on for charging to occur • Use optional car charger for charging in field

Hot Roofs • Operating temperature is 32 F to 104 F • Storage temperature is -4 F to 140 F • The SunEye left for half an hour in the sun can easily reach 130 F • Bubble in bubble level shrinks as temperature increases

If the bubble is really small, it means your SunEye is overheating. Put it in the shade until the bubble returns to normal.

SunEye GPS Add-On • Bluetooth GPS unit works with existing and new SunEye units • Detects latitude/longitude for session location and automatic sunpath generation • Records location of each skyline data set collected

SunEye GPS output to Google Earth™

Data transfer to computer via USB • SunEye stores more than 100 Skylines in memory • Transfer data to PC for further analysis • View and edit data in same way as on hand-held • Create reports and export files to design tools

Solar Access and Shade Report Client Information

• All session data is combined into a single hypertext document • Converts to MS-Word™ • View, Email, or print

Installer business information/logo

Access raw data files

Day

• Import data files into design software – Excel spread sheet, OnGrid, PVOptimize, PV*SOL, T*SOL, PVSyst, QuickQuotes, CPF Tools

1 2 3 4 5 6 7 8

Month Jan Feb Mar 54.17 54.99 67.64 54.17 54.99 67.64 54.17 54.99 67.64 54.17 54.99 67.64 56.63 54.66 67.77 56.63 54.66 67.77 56.63 54.66 67.77 56.63 54.66 67.77

Updated Software and Accessories • New software updates available from: www.solmetric.com – Includes handheld and PC updates – Set for auto-update

• Available accessories – GPS – Car charger – Hard-shell carrying case

SunEye tips Tips: • Use neck strap • Snap Skylines from multiple locations • Include worst case (eg. most south, lowest) • Use proper safety procedures

Photo courtesy of Matt Stone, SPG Solar

Help • User’s Guide accessible via desktop software – Help>Solmetric SunEye User’s Guide…

• Knowledge base at: – http://www.solmetric.com/knowledgebase.html

• Technical Support – 1-877-263-5026, opt 2 – [email protected]

Dec-Jan issue: “Solar Site Evaluation” www.solarprofessional.com

Questions?

Solmetric Corporation www.solmetric.com 1-877-263-5026