NI myRio: sensors needed for Solar Cell electrical characteristics

[BeDevian05]

Greetings,

I am a student working on a project on measurement automation using the NI myRio data acquisition device and the LabView platform. The main idea is to show the electrical characteristics of the solar cell like I-V, P-V, etc. 

I am looking hard to find some sensors for this project. I would need:

- A current and voltage sensor;

- temperature sensor;

- irradiance sensor;

- whatever I might have missed in this list.

Would really appreciate your help with this.

Best regards...

[Bob_Schor]

What experience do you have with digital data acquisition?  How much experience/knowledge do you have about your myRIO?

Most "signals", in order to be read by a computer, must be converted into a voltage.  Once you have a voltage, particularly if it is in a "friendly range" of, say, ±10 V, you can read it with an A/D converter (which you have on the myRIO), or if it is a "digital" signal (in the TTL range, 0 - 5V), you can sense it with a Digital Input port (which you also have on the myRIO).

To measure current, you need a resistor (or equivalent circuitry) to convert current to voltage. To read temperature, you need a thermistor or some other "temperature-to-voltage" converter.  I'm not certain what "irradiance" is, but you need an "irradiance-ometer" of some sort.

Bob Schor

[BeDevian05]

Hello Mr Schor,

Thank you for your reply.

I am really new at this whole thing. My goal is to achieve automation measurement of these electrical characteristics for a chrystaline Si pv cell. I want to measure the temperature, voltage, current and irradiance (which is the density of radiation incident on a given surface usually expressed in watts per square centimeter or square meter).

My idea is to use digital signals from digital sensors and create some UI graphis which will show the I-V graphs with the maximum power point. The whole point is to not use any voltmeters but only digital sensors.

Best regards

[Bob_Schor]

Where do you intend to get such "digital sensors"?  Voltage and current, for example, suggest that an "Analog-to-Digital Converter" (or an A-to-D converter) is required.  Well, LabVIEW calls things that do this a "DAQ" (for Data AcQuisition, I assume) device, and makes a number of them, some fairly inexpensive, that work very well with its DAQmx series of functions designed to help you get data "from the Real World" into LabVIEW for doing all of the things you want to do.

The myRIO, in fact, is loaded with DAQ inputs.  For Voltage and Current, it has A/D converters (you don't usually measure current directly -- see an Electrical Engineer (or a EE Student) for help with this).  There are various types of temperature sensors (depending on temperature ranges, speed of acquisition, etc.), but they probably also have a voltage output (again, no problem for the myRIO).  So all you need is an Irradiometer (I made that up!), but I'm certain you have a gadget (or know how to get one) that will give you a voltage reading corresponding to the Irradiance.  So let the myRIO do the Analog-to-Voltage conversion for you ...

Bob Schor

P.S. -- I'm currently working on a Project with a myRIO, and we are measuring Voltage and Currents from (let me see, 15 boards with 2 Voltage and 2 Current readings at maybe 10 kHz and 16 boards with 1 Voltage and 1 Current at 10 kHz) 46 Voltages and 46 Currents at 10 kHz, and we are not doing it with the myRIOs A/D converters!  Turns out each board had A/D Converter Chips on it, so we, in fact, do talk "digitally" to those chips, they do all the hard work, and then send the data digitally to the myRIO.  This is a lot harder than taking a few channels of Analog signals -- we are still working on it (though it mostly seems to work, now ...). 

Bob Schor

[BeDevian05]

Well, I have uploaded a drawing of the idea of my project. Probably you can understand it much easier. 

Please have a look at my upload image. Maybe you can give me a solution.

[GerdW]

Hi BeDevian,

---

@BeDevian05 wrote:

Well, I have uploaded a drawing of the idea of my project. Probably you can understand it much easier. 

Please have a look at my upload image. Maybe you can give me a solution.

---

This "idea" basically describes the same as is explained in the example projects provided by NI for RIO applications.

What about setting up a DAQ project using the PC as host?

So again:

• What have you tried so far?
• Where are you stuck?
• Did you already select all your sensors and actuators?
• Did you already design an electronics schematics for your setup?
• Did you take all those Training resources offered in the header of the LabVIEW board to learn LabVIEW and LabVIEW RT?
• Is your question about LabVIEW programming or about designing the whole (physical) DAQ system?

This forum willnot provide "solutions" for free, but will answer your (specific!) questions as best as possible…

[BeDevian05]

Thank you for your reply.

I am very new at all of this including programing or drawing electronics schematics. But I have been watching the labview training and also reading a myRio book of speifications.

I have thought as a first step I would selet the right sensors for this project and this is where I am stuck at. About the schematics, I plan to learn as I go on and of course I do not want this to be solved by someone else otherwise what is the point.

Would really appreciate any guidance towards the selection of the sensors for this project. Whatever knowledge you can share, would be of a great value to me.

Kind regards.

[GerdW]

Hi BeDevian,

---

@BeDevian05 wrote:

But I have … also reading a myRio book of speifications.

---

So you know which kind of signals you can read with your myRIO (easily).

---

@BeDevian05 wrote:

Would really appreciate any guidance towards the selection of the sensors for this project.

---

Now you need to look for sensors being able to measure the properties which you want to measure. Try to select sensors suitable for the input signals of your myRIO - which you know by now after reading the datasheet…

[BeDevian05]

Hi GerdW,

Really appreciate your guidance.

I was hoping for a direction as to which webpage or which company can I look for these sensors so that I can order. This is what I am really stuck at and not at recognising the sensors.

Kind regards.

[GerdW]

Hi BeDevian,

there are a lot of distributors delivering their items worldwide.

Just to name a few I've been in contact with: Mouser, RS, Conrad, Arrow, Distrelec, Digikey, avnet…

(You could also just start your favorite internet search engine and search for your type of sensor, like "current sensor 100 A voltage signal".)