Modules are the key to capturing light and creating power
but how important is it to spend hours trying to decide which one is best for
me?
Well it depends.
It is basically a cost benefit decision. Limited roof space would require a more
efficient module in order to achieve higher power production at potentially a
higher cost per watt. On the other hand
if you have a large roof space, you could use a less efficient module at
potentially alower cost per watt to generate the same energy production as the
higher cost modules.
You have to look at your potential power production and decide
whether the additional cost for a more efficient module would net out at more dollars
for you in the long term.
There is some nomenclature you would need to know when
evaluating modules. This is handy when
comparing modules. A common test
situation needs to be defined so the data can be replicated anywhere in the
world and provide common data points.
There are 2 standards that you will see when discussing modules.
STC
Means Standard Test Conditions. Module performance is
generally rated under standard test conditions (STC): irradiance of
1,000 W/m²,
solar spectrum of AM 1.5
and module temperature at 25°C.
Basically, this
defines a standard test that manufactures and test labs perform to test a
module. The companies would have a indoor
solar testing simulator that meets the standard and therefore you would have a
common data standard in order to compare
modules.
You would find STC in this context: A Siliken solar module
is 240 Watts (STC). Therefore 10 Siliken
modules would be 2,400 Watts (STC).
PTC
Stands for PVUSA Test Conditions. This is much closer to real world
conditions. You will find this value
being used in California. They use this
to obtain the rebate that is provided in this jurisdiction. PTC are 1,000 Watts per square meter solar
irradiance, 20 degrees C air temperature, and wind speed of 1 meter per second
at 10 meters above ground level
Other things to consider is the warranty for power and
manufacture defects and power production over the 20 year period. But beware, the company might have a great warranty but
will they be in business in 15 years?
Modules will lose efficiency year to year and this is stated in the
warranty. The warranty may state something like this:
25 year linear power warranty/assuring 97% performance level
the 1st year, from the 2nd to the 20th year module degradation is guaranteed to
be less than or equal to .7% per year (Siliken module performance warranty). Modules are made to last. I’ve seen a module that has been in continuous
production since 1987; it’s slightly discoloured but still functioning. Your modules should have a productive lifetime
much greater than the 20 years warranted.
They are also designed to stand up to hail stones of a certain size and
velocity.
2012 is the year of
implosion for module production-lots of companies have gone out of
business. What also is important is the
temperature cooeficient- lower is better.
The lower the number the more efficient the module is at a high
temperature.. Why this is important is that the modules can get very hot in
direct sunlight 40- 50 degrees celsius.
Higher module temperatures will reduce the voltage by 0.04 to 0.1 volts
for every one Celsius degree rise in temperature (0.04V/°C to O.l V/°C).
Here is another explanation that I picked up while surfing
the net:
Unfortunately, the 25ºC cell temperature used for testing is
not a typical operating condition. In full sun, PV modules typically operate
between 15°C and 30ºC (approximately 60°F to 90ºF) above the ambient
temperature depending on how they are mounted (flush on a roof, on top of a pole,
etc.). Thus, on a 25ºC (77ºF) day, cell temperature may be closer to 50ºC
(122ºF). On a hot summer day, cell temperature can routinely approach or exceed
65ºC (149ºF). As cell temperature increases, voltage decreases. A decrease in
voltage, at the same level of irradiance, means a proportional decrease in
power.
Side by side, and all else being equal, a module with
a 43ºC NOCT (nominal operating cell temperature) should produce about 3% more power than a
module with a 50ºC NOCT.
The state of California does an review of modules and
provides their own real word evaluation using PTC rather than STC
In
Ontario, Canada you are restricted to modules manufactured or assembled
in Ontario. There are a few companies
such as Silfab, Heliene and Canadian Solar to name a few that manufacturer in
Ontario
Unfortunately there are many more manufacturers out there
such as Sunpower (who make excellent and
efficient modules) which do not qualify as meeting the Ontario MicroFIT
regulations. For those of you going
solar but not through MicroFIT, then you have a wider range of options. From a price perspective take advantage of
the cheap Chinese modules that are entering the market. Whether this is dumping
or just that fact that the Chinese have decided to build capacity in this area,
I don’t know but the prices are great.
You can search for current Ontario Solar Module
Manufacturers by navigating to:
https://www.showreg.net/OSEI2009/default.asp?mode=2
Ontario Made Module Links
http://osmsolar.com/products.html
http://www.heliene.ca/
http://www.silfab.ca/
http://www.heshomeenergy.com/sharpsolarpanels.html (no website)
http://www.wsetech.com/solar%20panels%20csa.php
http://solgate.ca/about/
http://www.luminsolar.com/
http://www.eclipsall.com/
http://www.canadian-solar.ca/residential/
http://www.luminsolar.com/
http://www.magnum-solar.com/
http://ca.sanyo.com/News/-For-Reference-SANYO-Solar-Modules-used-for-Markham-s-first-municipally-owned-Solar-PV-Rooftop-project-to-power-under-the-Ontario-s-Feed-In-Tariff-program
http://www.schueco.com/web/ca/residential/solarheat_solarpower/products/photovoltaic_systems/pv_modules
http://www.solarizetech.com/
http://www.unconqueredsun.com/
http://www.soventix.ca/
Key points for Installation of modules on your roof
Orientation
For proper operation, the modules must be oriented as close
as possible
toward the equator. In the Northern Hemisphere, this
direction is south.
In most areas, this varies from the magnetic south given by
a compass. A
simple correction must be made.
Height from roof
4-6” to allow proper ventilation and reduce heat although
the modules can be mounted lower for visual appeal.
Angle of inclination
Permanently mounted modules should be tilted up from the
horizontal . The correct tilt angle varies
with the times of year the system is used, and the latitude of the site.
The tilt angle is measured from the horizontal, not from a
pitched roof or hillside.
The tilt should be within 10 degrees of the listed angle.
For example, a system used throughout the year at a latitude of 35° can have a
tilt angle of 25° to 45° without a noticeable decrease in annual performance.
