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Advancement and Development of Electricity and Technology
Building Integrated PV
Bypass diodes
Determining low temperature that caused the inverter to go over voltage
Another NABCEP PVIP Certificate in the mail!

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Feeder PV Connections 705.12(D)(2)(1)(b)
Crimping MC4 Connectors without the tool
Converting kWh to pounds of CO2
NEC 310.15(A)(2) Exception, 10% or 10 feet or less for sizing conductors
PV Temperature coeficcients in V/C, mV/C and %/C with conversion examples

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NABCEP PV Technical Sales Exam Study Group (which will evolve into a full course)

Feedback from the first NABCEP PV Technical Sales Online Group


Submitted: 04/23/2016
Training: NABCEP PV Technical Sales Exam Prep Discussion Group / Online / Anytime

How would you rate this course?
10/10
What did you like about the course?:
The pace for me was good, also questions with answers really helped. In the 5th week I got bombarded with work so was playing catch up.
How effective was the instructor's communication during the course?:
Very good, seems like my teammates asked the same things I was thinking.

Post NABCEP PV Technical Sales Exam


Comment:

Hey Sean, the exam went great! Youe prep course and material more than prepared me for the exam. I think you did a great job with us these last 6 weeks. There was not 1 question I was not able to handle.

Reply:

Thanks for the feedback!
Glad to be able to help!!
Sean

8-days pre-exam strategy


8-days until the exam!

My advice is now is the time to study a lot. No procrastinating. Do not worry too much about obscure things that will probably not be on the exam. Do not spend too much time trying to understand the one thing that you do not understand. It is a numbers game and nobody ever gets all of the questions right.

Plan to be done cramming 2 days before the exam, when it is time to get rest and review. Remember that a good state of mind and a clear head will be the best thing that you can accomplish the night before.

PV Inter-Row Spacing Methods


Q:

Thanks Sean. Do you know which formula they would expect us to use? I've run across several in previous studies of varying accuracy levels:
Basic inter-row shading distance
(d) = 3H
H = height of module from back edge to surface

Better inter-row shading distance
(d) = H/tan AltA
H = height of module from back edge to surface
AltA = Altitude Angle on December 21st at 9:00 AM

Best inter-row shading distance:
(d) = [ (Sin TiltA) x M ] / tan AltA ] x cos AzAD

Converting kWh to pounds of CO2


Q:

Looking at the joint task analysis for non-financial benefit analysis it says to know how calculate CO2 avoidance, tons of coal saved, water saved, miles not driven, etc. Is that really something they would ask us how to calculate? Tons of assumptions go into each of those and several vary by geographic location. Any particular rules of thumb to remember for them or is it more likely they would give us all the inputs/assumptions and just ask us to calculate them based on lifetime kWh production of the system?

Delta Kelvin is the same as delta Celsius


Q:

Oh and I was reminded today that mV/C(elsius) and mV/K(elvin) are the same thing but sometimes the spec sheets show it in mV/K which can be confusing.

A:

I think that the engineers making the datasheets that are using Kelvin instead of Celsius are just trying to impress people at how educated they are. They probably tell their family the weather forecast in Kelvin and have a big Kelvin thermometer on their front door. They probably have birthday parties for when their kids turn pi years old or the square root of 3.

705.12(D)(2)(2) and 240.21(B) 10-foot Tap Rule and 25-foot Tap Rule for PV Systems


Q:

I'm not super clear on the 10 ft. and 25ft. tap rules. Can you provide some concrete examples of how the conductor size is calculated for each of those?
 
A:
 
Let’s start first with the 10-foot tap rule and then infer the 20-foot tap rule from what we learned with the 20-foot rule.
 
Imagine a feeder going from a main panel to a sub panel. That feeder has a 200A breaker at the main panel.
 
Imagine that we want to connect a very small 8A inverter to the middle of that feeder.

690.11 dc Arc Fault Protection and 690.12 Rapid Shutdown of PV Systems


Q:

I've been reading recently about 2014 requirements for arc fault protection (690.11) and rapid shutdown (690.12). Both seem relevant for sales personnel, particularly the rapid shutdown requirements because of the potential for added equipment. Any good resources folks can recommend in this area?
 
A:
 
You are right, it is important for sales people to understand 690.11 dc arc fault protection and 690.12 rapid shutdown requirements.

PV Temperature coeficcients in V/C, mV/C and %/C with conversion examples


Q:

One thing I remember from working on temperature co-efficients before is the importance of paying attention to whether the co-efficient is given as a percentage or in volts/degree. If it's in voltage/degree, which I've seen on some spec sheets, than you've got one less step to do.

A:

Good point! Usually it is given in percent per degrees C and it can confuse some people if all of the sudden the coefficient is given in volts or mV per degrees C.

Polycrystalline, Multicrystalline, Monocrystalline, CdTe, CIGS and Gallium Arsenide


Q:
 
How much time is it worth to spend on the various types of cells and their chemical structures and construction methods? Or is it sufficient just to be aware in general of the different cell types (mono, poly, CIGS, CdTe, etc.) and their performance characteristics?
 
A:

Since you are studying for a Technical Sales Exam, I would recommend not worrying about getting into the different details about the chemistry if you have limited time.

Voltage Drop and Bypass Diode Alternatives


Q:

Ch 3 Question: Will we be asked to calculate voltage drop on the exam?
 
Ch 4 Question: Have you used optimizer/chips instead of bypass diodes? Jinko modules use them and they appear to be much better than bypass diodes in terms of losses.
 
A:
 
To answer your question 3 about voltage drop first:
 
I do not think you will be asked to calculate voltage drop on the NABCEP PV Technical Sales Exam, but you should understand what voltage drop is.

Compounding Interest


Q:

Compounding Interest: I thought this was a simple formula(s) to memorize. Just remember to subtract from 1 for module degradation and inflation. Add to one for interest rates.

A:

I think a lot of textbooks make things as difficult as possible to understand, because the author is trying to impress the other instructors.
Glad you think it is simple to understand.

Einstein said:

"Everything Should Be Made as Simple as Possible, But Not Simpler"

Voltage, Current, Magnetic Declination, Power Factor, Tilt Angles and Busbars


Q:

I have just finished Ch:1-6 of you book. It was very clear, informative, and funny. Here are my questions/comments from Ch 1 on the facts & Figures. FYI, I am a visual learner.
1. Do you know of a video/resource that reviews IV curves (Isc, Imp, Voc, Vmp)?
2. Do you know of a video/resource that explains optimal tilt angle . Any practice questions would also be helpful
3. Can you expand on the power factor? Why is it significant?
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