|
Copyright
©Denis Lenardic 2001-2010 All Rights Reserved
Friday
12th Mar, 2010
19:36
This page was last time updated on
14th Feb, 2010
|
Solar radiation estimation and site analysis
"Turn your face to the Sun and the shadows fall behind you."
(Maori proverb)
Where are you: Home > Site analysis
The
choice of a proper location is the first and the very essential
step in solar system design procedure. Even the most carefully
planned solar system doesn’t work satisfactory, if the location
wasn’t properly chosen. It is critical that the modules are
exposed to sunlight without shadowing at least from 9 am to 3 pm;
therefore, the properties and values of solar insolation should
be studied. The modules have to be fixed with proper tilt angle
allowing the system efficient operation.
Other topics:
Software >
Modules
|
Sun path
|
|
Understanding the motion of the Sun is essential for proper solar systems design
and the choice of proper location for solar collectors or photovoltaic modules.
The solar path is described with the Sun path diagram. The Sun path
diagram is a very useful tool in the early photovoltaic system design
phase for shadowing determining. The most important geometrical
parameters, which describe Earth-Sun relations, include declination
/δ/, Sun height /α/ and Solar azimuth /φ/. They are defined
as follows:
h = ±15o· ( number of hours from/to solar noon )
n = day of the year
Sun path diagram, created with SunOrb 1.2
Solar azimuth
Sun height
According to the equations above we can estimate the most proper photovoltaic
modules tilt employing the following equation:
Declination
Tilt angle for different latitudes
Declination changes throughout the year, therefore, the optimal tilt angle
changes as well. The optimal tilt angle of 46° N latitude can be
seen in the picture above.
|
|
Tilt and azimuth angle of photovoltaic modules
|
|
The
proper tilt and azimuth angle choice is by far more important for
photovoltaic systems design than solar thermal system design. Manual
or automatic tilt angle adjustment can increase the total
light-electricity conversion up to 30 % and more in locations with
high values of solar radiation. Incidence angle should be as close to
90° as possible. Photovoltaic module tilt angle and location
choice in general require more care than solar collectors tilt angle
and location choice. Shaded locations, including partially shaded,
are not suitable for photovoltaic module fixation. Modules should be
south oriented. The following general recommendations should be
considered, if you design a photovoltaic system:
Yearly
average maximum output power - the photovoltaic modules tilt
angle should equal local latitude.
Maximum
output power in winter - the photovoltaic modules tilt angle
should equal local latitude + 15° (max +20°). Such a tilt
angle is a good solution in areas, where the winter load is greater
than the summer load. The electricity consumption for lighting is
greater during winter than summer.
Manual
photovoltaic module tilt angle adjustment - in small systems
modules should be fixed in a way, which allows manual adjustment of
the module tilt angle. In March the tilt angle should be adjusted to
equal latitude, in May the tilt angle equals latitude minus 10
degrees, in September the tilt angle equals latitude and in December
the tilt angle equals latitude plus 10 degrees. With such an
adjustment the maximal efficiency could be obtained throughout the
year.
Accurate
and maximum energy output of larger systems should be based on exact
calculations, because energy output is influenced by different
factors, such as local climatic conditions (solar radiation
availability in different seasons, local cloudiness or fogginess in
winter, temperature and so on). You will need a long-term solar
radiation data for the chosen location.
|
|
Tools for site analysis
|
|
|
Solar Pathfinder - The Solar Pathfinder has been the standard in the solar industry for solar site analysis
for decades. Its panoramic reflection of the site instantly provides a full year of accurate
solar/shade data, making it the instrument of choice.
 |
|
Solar Pathfinder
- a powerful non-electronic instrument that includes:
- Printed Manual (online version also available)
- Sunpath Diagrams (latitude & application specific)
- Angle estimator (for determining altitude and azimuth)
- White marking pen with extra leads
- Tool box specifically designed for the Pathfinder™
|
|
Solar Pathfinder™ gives an entire year’s solar potential for a given site in just seconds. This non-electronic instrument is ready-to-use upon receipt of shipment.
Solar Pathfinder Assistant is companion software that generates monthly sunpaths for each specific site latitude instead of relying on the stock latitude band diagrams. It includes weather data for North America, Central America, Europe, and Southwest Pacific.
Click here to learn more
|
|
|
|
SunEye™
The Solmetric SunEye™ (patent pending) is a hand held electronic device that allows
users to instantly assess total potential solar energy given the shading of a particular
site. Identifying the shading pattern early in the process reduces the expense of system
and home design and improves the efficiency of the final system or house.
|
|
|
SunTracker
is an iPhone® based site evaluation tool, providing full solar site analysis in an affordable hand held package.
|
|
|
HORIcatcher
HORIcatcher is an easy and fast tool to take outdoor pictures of the horizon.
The pictures can be used to determine the solar energy input, sunshine duration and
sun exposure reduced by obstacles like trees, houses or mountains. HORIcatcher
is supplied with a digital camera.
|
|
|
Panorama master
with "Panorama master" you can make exact matched set of photos - base for panorama picture (see also "Horizon" below).
|
|
|
Horizon
software simulates sun path diagrams for arbitrary latitude.
|
|
|
Sonnenbahn Indikator Pro
is a simple tool for site evaluation.
|
|
|
Pilkington Sun Angle Calculator
This handy tool provides a relatively simple method of determining solar geometry variables
for architectural design, such as designing shading devices or locating the position of the
sun relative to a particular latitude and time.
|
|
Software for site analysis
|
|
|
Sun path
chart
this program creates sun path charts in cartesian or polar
coordinates for "typical" dates of each month (i.e.; days receiving about
the mean amount of solar radiation for a day in the given month).
|
|
|
Shadow Analyser -
Shadow Analyzer is an advanced parametric CAD tool
for professionals in the area of Solar Energy Engineering and Architecture.
Languages:
|
|
|
METEONORM
-
Global Meteorological Database for Solar Energy and Applied Meteorology.
METEONORM is a comprehensive climatological database for solar energy applications:
a meteorological database containing comprehensive climatological data for
solar engineering applications at all points of the globe between the polar
circles; a computer program for climatological calculations;
a data source for engineering design programs in the passive, active and
photovoltaic application of solar energy with comprehensive data interfaces; a
standardization tool permitting developers and users of engineering design
programs access to a comprehensive, uniform data basis.
Languages:
|
|
|
ECOTECT -
is an industry leading building analysis program that allows designers to work easily in 3D and apply
all the tools neccesary for an energy efficient and sustainable future.
Languages:
|
|
|
Sombrero
A PC-tool to calculate shadows on arbitrarily oriented surfaces.
For both, active use of solar energy (domestic hot water, photovoitaics)
as well as for passive solar architecture, shading or lighting of
planes plays an important role SOMBRERO provides quantitative results for
the shading of collectors or windows by buildings, trees, overhangs or the horizon.
|
|
Solar radiation and site analysis - related web sites
|
|
|
Focus Solar -
Focus Solar is a leading provider of solar energy information services for the
design, planning, and performance monitoring of PV systems. The specialty of
Focus Solar is the use of weather satellites for solar energy applications. PV
system planners and developers derive a unique value from the combination of
geophysical science and PV engineering. Service is available in English,
Spanish, and German. Free information is offered for PV system monitoring and
a survey of PV product quality.
Languages:
Webmaster's choice -
solar radiation data and yield estimation provided by professionals.
|
|
|
Renewable resource Data Center -
The RReDC provides information on several types of renewable energy
resources in the United States, in the form of publications, data, and
maps. An extensive dictionary of renewable energy related terms is also
provided.
Languages:
Webmaster's choice -
solar radiation terms, glossary, alghoritms, models etc.
|
|
|
Logiciel CalSol
Estimation de l'énergie solaire disponible pour une application ´nergétique.
Languages:
|
|
|
GIS Assessment of Solar Energy Resource in Europe -
On this site you can find an information on GIS-based inventory of solar
energy resource and estimations of the potential photovoltaic (PV) electricity
generation in Europe.
Languages:
Webmaster's choice -
PV potencial in Europe - estimations, maps, charts and detailed explanations of calculation methods. Excellent site for profesionals!
|
|
|
Volker Quaschning -
private web site about renewable energy use and application.
Languages:
Webmaster's choice -
a lot of useful documents available for download. Shadowing analysis and simulation explained in detail.
|
|
|
Photovoltaics and snow -
private PV related web site. Interesting section about snow and photovoltaic modules also included.
Available in dutch language only.
Languages:
|
|
More information and some useful on-line tools
|
|
Sun Position Calculator - on Line tool by Volker Quaschning. Calculation of Sun Position, Sunrise and Sunset.
Meeus, J.: Astronomical Algorithms; Willman-Bell Inc., Richmond, VI,
1999.
Muneer, T.: Solar Radiation and Daylight Models; Elsevier, Butterworth-Heinemann, Oxford, 2004.
Scharmer, K, Greif, J.: The
European Solar Radiation Atlas, Vol. 1: Fundamentals and
maps.
Scharmer, K, Greif, J.: The
European Solar Radiation Atlas, Vol. 2:
Database and exploitation software.
|
|