The Basics

When you are talking Solar you are talking another language. Personally, I get confused when talking about Kilowats (Kw) and Kilowatt hours(Kw/hr).  What the heck is an “LDC” anyways..stuff like that

DC 

Stands for direct current.  The energy from the light is generated as DC power.  You can use microinverters attached to the module to convert the DC power to AC or a inverter placed near your outbound energy meter.

AC

Stands for alternating current.  You need to convert the DC current to AC in order to transfer power to the grid since the grid is AC. The device used to convert from AC power to DC power is called an inverter

Interesting side note: In the dawn of the electrical age, Telsa and Westinghouse proposed AC electricity as the standard for homes and transmission against Thomas Edisons  who proposedDC electricity.  Edison lost the argument and today our grid is AC except for Quebec where their long distance transmission towers are DC.  That is why most homes and electrical distribution is AC not DC.

Angle of Inclination

This is the angle that the solar modules will be installed at if in a fixed position such as your roof.  This angle will change in regards to your position on the earth and throughout the year as the sun’s position will change season to season. If you were to attach a volt meter to your module and change the angle from 0 to 90 degrees you will see the display change as you reach the optimum angle for your location/time of year and then move lower as you move past this point.  So determining the best average angle of inclination will provide you with the most efficient angle for energy harvesting.

This powerpoint that I found in the web (sorry I can’t attribute it to anyone as there isn’t any label/attribution etc) explains the concept very well.

http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&ved=0CF8QFjAEOAo&url=http%3A%2F%2Fwww.cabrillo.edu%2F~lsonsino%2FChapter%25202%2520Solar%2520Radiation%2FSolar%2520Radiation.ppt&ei=_8cjUPb0GcaDywGCwYHYBA&usg=AFQjCNESy_YCNK3ygB2GWfiBbbM5FWExqA&sig2=ZNfCugt70a24KC-NGQ9idg

This is a very technical discussion about Angle of Inclination for those inclined to read  very technical articles:

http://www.physics.arizona.edu/~cronin/Solar/References/Shade%20effects/sdarticle%20(18).pdf

Azimuth

The solar azimuth angle is the azimuth angle of the sun. It is most often defined as the angle from due north in a clockwise direction.  Positive 90 degrees is facing due west, negative 90 degrees is facing due east. The compass angle shows 180 for south, 90 for east and 270 for west.

This is a good discussion of the implications of how a change in the Azimuth from due south would affect your energy output.  Depending upon how you use or get paid for your energy (i.e microFIT vs. using the energy yourself), it could still be financially feasible to have a system that is considerably off South.  You have to do the modeling and calculations to determine this.

http://www.civicsolar.com/resource/effect-azimuth-angle-energy-output

ESA

Electrical Safety Authority.  ESA is responsible for administering specific regulations related to the Ontario Electrical Safety Code, licensing of Electrical Contractors and Master Electricians, electricity distribution system safety, and electrical product safety.  They are important to you because they must certify your newly installed solar system prior to connection to the grid.

http://www.esasafe.com

Derate

A series of factors that affect system performance that are factored into the final calculation of system efficiency and and energy harvest.

This is an excellent article that explains Derate by component:

http://homerenergy.com/documents/SolarPro3_%20Production%20Modeling%20High%20Res_201004-1.pdf

A derate calculator:  

http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/derate.cgi

Kilowatts

A unit of power equal to 1000 watts

Example: 1 light bulb that is 100 watts.  10 -100 watt light bulbs = 1 Killowat

Kilowatt hours

Number of hours 1 killowat is generated

Example- If you use 1 kilowatt for 1 hour you now have 1 kilowatt hour

10 lightbulbs burning for 1 hours = 1 kilowatt hour.  So if you are billed  .9 cents a kilowatt hour, the cost of burning 10 lightbulbs for one hour is .9 cents

Watts  

The watt (abbreviated W) is the International System of Units' (SI) standard unit of power(energy per unit time), the equivalent of one jouleper second. The watt is used to specify the rate at which electrical energy isdissipated, or the rate at which electromagnetic energy is radiated, absorbed, or dissipated.In DC (direct-current) and low-frequency AC (alternating current) electrical circuits and systems, power is the product of the current and the voltage. Power is also proportional to the ratio of the square of the voltage to the resistance, and to the product of the resistance and the square of the current.

LDC

Local Distribution Company.  This is the short form used in the industry to describe the location power distribution company, which in Ontario could be Powerstream, Toronto Hydro, Algoma Power  etc. Here is a list of LDC’s in Ontario:

http://www.eda-on.ca/eda/edaweb.nsf/0/37f4c86af0c0f5f685256d48005abf95

O & M

You might see this term when doing a spreadsheet or talking about financials-means ownership and management. The term might be used when talking about the system cost over a number of years. i.e “what’s the O&M over the 20 year period?

MicroFIT

Fit stands for Feed in Tariff, meaning you would be feeding the electricity you had generated from your PV system into the grid.  Micro is just a term in Ontario to differentiate systems under 10 Kw which would operate under one set of rules from FIT which are installations that are larger than 10 Kw.  This is the link to the Ontario MicroFIT website.  MicroFIT rules have been revised as of July 12, 2012.

http://microFIT.powerauthority.on.ca/

MMTP

This is a technique that companies use to get the maximum power.  It is an algorithm that a company integrates into its electronics and is performed on the fly as the power is being produced.  This technique is useful when you have shading as it will calculate for best power on your string or module when the module is shaded or in another example when it is very cold outside.  Power generation gets more efficient when colder and the MMTP device will take this into account and maximize power.  Examples of devices that are separate from the inverter would be the Solaredge optimizer or the Enphase microinverter.  These devices would track individual modules for MMTP while a Powerone Aurora would have the ability to have 2 separate strings  tracked.

This site uses an analogy of a cars transmission to discuss MMTP which might be clearer than my approach.

http://www.wholesalesolar.com/Windy/MPPT-article.html

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

An excellent explanation is provided here:

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

To see actual usage of PTC and also to introduce you to an excellent chart on available solar modules and their rating by the State of California go here:

http://www.gosolarcalifornia.org/equipment/pv_modules.php

SLD-Single line drawing

This is usually supplied by the Installer and is an electrical line drawing showing the circuit and how they will be setup and connected.  It is required by the LDC when submitting the micro generation application.

Solar Module definitions

 Rather than repeating what a number of bloggers and companies have produced already, please find the link below with the definitions so that you can actually understand what the spec are for modules.  This site has an excellent listing of solar modules and their specs as well.

http://www.posharp.com/photovoltaic/panelefficiency/database.aspx

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). 

Temperature Coefficient Pmax

There are a lot of terms that are very technical. I have been told temperature Coefficient  Pmax is the  most important one for the layman.

If you look at the manufacturer's data sheet you will see a term called "temperature coefficient Pmax". For example the temperature coefficient of a Suntech 190 W (monocrystalline) solar panel is –0.48%. What this means is that for each degree over 25˚C … the maximum power of the panel is reduced by 0.48%.

So on a hot day in the summer – where solar panel temperature on the roof might reach 45˚C or so – the amount of electricity would be 10% lower.

Conversely, on a sunny day in the Spring, fall, or even winter – when temperatures are lower than 25˚C – the amount of electricity produced would actually increase above the maximum rated level.

Volts

The SI unit of potential difference and electromotive force, formally defined to be the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between these points is equal to one watt.I will continue to add and edit this glossary over time as there are many more technical words that may be foreign to you.  If you see any errors or would like me to add additional definitions that you may have encountered, please send me a note. 


I have also found this website to have an excellent glossary of Solar terms that you may find useful.

http://www.altestore.com/store/glossary/

or one provided by SMA the inverter people that is also very extensive

http://www.solar-is-future.com/faq-glossary/glossary/index.html

Here’s a dictionary produced by a co-op in the States that put together a community rooftop solar system

http://www.muellermegawatt.org/resources/solar_dictionary/solar_dictionary.html