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Measuring Solar Radiation based on Photovoltaic Cells
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(16-06-2015, 23:53)AllyCat Wrote:  As for the relative pros and cons of Panels v Diodes, that could (and maybe should) fill another thread (i.e. not this one). But its probably easier to "level" a Panel to within the one degree horizontality which is suggested as being necessary for good (Cosine response) results.

I will start by your last paragraph, because it is absolutely relevant to explain why I chose the PV cells way:
First: All the process seems easy to be understood by almost everyone with a basic electronics knowledge, like me.
Second, but very important: Everything in the WeatherDuino Pro 2 project was thought with the assembling in mind. It have to be easy enough to be built at home without special equipment. And in fact it's a lot more easier find a suitable box that allows leveling a PVcell, within one degree horizontal position, than a unit built with a photodiode which will require a great degree of precision in positioning the sensor (due to it's very small surface). Find a suitable teflon difuser for the photodiode may not be so easy too.
Maybe it's a fault of my way of being, but I always think in first place, in the practical or physical implementation. How am I going to ride it? How this could be built with simple materials?

(16-06-2015, 23:53)AllyCat Wrote:  The Davis gives you a considerable advantage, because probably the most difficult issue with this part of the project is calibration, which basically requires the availability of a reliable reference device (and a considerable amount of time and effort). Personally, I'm at a further disadvantage, that I live in London, where the sunshine cannot be considered "reliable" and I doubt if even a rare "clear sky" will enable me to calibrate my sensor accurately

Two years ago, in summer with very clear sky, I spend several full days doing measures and comparing results... at sunrise, during the day, at evening. My garden was full of wires, voltmeters, Arduinos and PVcells. It really was a very laborious job, but done with pleasure.
What about to come to Portugal in the summer to calibrate your sensor? Smile

(16-06-2015, 23:53)AllyCat Wrote:  However, I do have two FO Solar Pods (one "on the roof" the other "on the bench") which I believe have a claimed accuracy of +/- 15%, but I doubt if mine even agree by that tolerance. Certainly they do quote the "sunshine" in Lux, but I'm not sure that they actually use a "Visible Spectrum" sensor, rather than a standard Silicon Diode (Visible + Infra Red), nor whether they attempt to achieve a "Cosine" directional response. Their more recent "Solar" stations are switchable between "Lux" and "watts/m2" (except that they got the conversion factor totally wrong ! ), but I very much douibt if they change the spectral response of the sensor.

As you well know there isn't a correct formula to convert lux to w/m2, or better, it exists, but is only valid for the wavelength corresponding to the green light. I'm sure I already seen another formula which result in a more correct conversion factor, but I don't know which one FO is using. My first attempts to built a "solar radiation" sensor were based in a light intensity sensor (output in lux). When I start to learn more about the conversion process, I gave up instantly of this idea. SmileSmileSmile

(16-06-2015, 23:53)AllyCat Wrote:  Therefore, my involvement has to be more on a "theoretical" basis. Sometime I may explain my own project in more detail, but itwould take this thread too far Off-Topic. Wink

Feel free to create a new thread when you wish. Will be a pleasure read it, and I'm sure that I'm not the only one who could say this.

(16-06-2015, 23:53)AllyCat Wrote:  In principle, it should be quite possible to use either a PV panel or a photodiode such as the BPW34xx with your hardware, particularly if the load resistor is connected directly to the panel/diode (which I agree it should). The adjustment pots give a wide range of gain control, but if we assume the wipers are near the "middle of track" then the nominal gain looks to be around 5.

A PV Panel nearly always contains a number of "diodes" in series, so the ~200mV required at the input of the Op-Amps is probably a sufficiently small proportion of its Open-Circuit voltage. A single diode like the BPW34xx generates only about 400 mV, so you should probably keep the "short circuit" voltage below about 100 mV. But the Op-Amp can easily give this higher gain. I believe the "naked" diodes generate about 7 mA (i.e. 1 mA / mm2) in full sunlight, so a shunt resistor of around 15 ohms could be about right.

Mathematics never fails, isn't it? Your deductions based on the parts values on the schematic are absolutely right.
With the PV cells that I'm working now, I'm using a shunt resistor of just 1 ohm, which gives me a maximum voltage drop ("short circuit" voltage) around 150 mV at the shunt resistor.
The field tests reveal reasonable results adjusting the pot to get a OP gain around 7.

Cheers, Caneira



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Messages In This Thread
Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:37
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:38
RE: Measuring Solar Radiation based on Photovoltaic Cells - by fehmi - 04-02-2016, 21:21
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 05-02-2016, 02:46
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:40
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:41
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 07-09-2014, 11:46
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 08-09-2014, 20:30
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 09-09-2014, 11:24
RE: Measuring Solar Radiation based on Photovoltaic Cells - by water01 - 09-09-2014, 00:13
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 09-09-2014, 03:52
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 09-09-2014, 15:13
RE: Measuring Solar Radiation based on Photovoltaic Cells - by water01 - 09-09-2014, 20:17
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 09-09-2014, 22:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by water01 - 09-09-2014, 23:15
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 10-09-2014, 00:45
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 12-01-2015, 13:50
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 14-01-2015, 20:15
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Brett - 13-01-2015, 12:09
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 13-01-2015, 12:42
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Brett - 24-01-2015, 23:09
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 24-01-2015, 23:26
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Brett - 25-01-2015, 08:51
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 25-01-2015, 19:42
RE: Measuring Solar Radiation based on Photovoltaic Cells - by tyntop - 02-02-2015, 23:52
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-02-2015, 03:27
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 01-04-2015, 17:06
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-04-2015, 03:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by strkomis - 29-05-2015, 08:20
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 29-05-2015, 10:52
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 29-05-2015, 18:40
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 02-06-2015, 11:22
ideas to improve the measuring of solar radiation - by hvalentim - 03-06-2015, 11:01
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-06-2015, 11:50
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 03-06-2015, 13:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-06-2015, 17:33
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 05-06-2015, 15:28
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 11-06-2015, 04:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 11-06-2015, 18:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by tyntop - 11-06-2015, 19:26
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 11-06-2015, 19:47
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 11-06-2015, 20:17
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 12-06-2015, 00:44
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 12-06-2015, 06:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 12-06-2015, 13:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 12-06-2015, 17:43
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 13-06-2015, 00:16
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 16-06-2015, 11:08
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 13-06-2015, 01:02
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 13-06-2015, 00:49
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 13-06-2015, 00:56
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 13-06-2015, 11:11
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 14-06-2015, 02:41
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 16-06-2015, 23:53
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 13-06-2015, 14:19
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 16-06-2015, 15:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hvalentim - 16-06-2015, 16:26
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 16-06-2015, 17:26
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 17-06-2015, 02:52
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 30-06-2015, 18:16
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 30-06-2015, 21:28
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 12-07-2015, 11:30
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 12-07-2015, 15:19
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 12-07-2015, 16:43
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 12-07-2015, 23:31
RE: Measuring Solar Radiation based on Photovoltaic Cells - by zitoune - 18-07-2015, 02:40
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 16-07-2015, 14:19
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 18-07-2015, 03:46
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 18-07-2015, 15:32
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-08-2015, 02:47
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 18-07-2015, 15:40
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 18-07-2015, 15:59
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 19-07-2015, 10:26
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 19-07-2015, 17:57
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 20-07-2015, 10:49
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 20-07-2015, 11:07
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 20-07-2015, 11:17
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 21-07-2015, 16:25
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 24-07-2015, 02:38
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 25-07-2015, 15:44
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 02-08-2015, 14:27
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 02-08-2015, 15:42
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 02-08-2015, 17:30
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 03-08-2015, 17:22
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 03-08-2015, 04:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-08-2015, 22:53
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 03-08-2015, 12:38
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 03-08-2015, 13:47
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 08-08-2015, 07:39
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 08-08-2015, 15:21
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 09-08-2015, 14:48
RE: Measuring Solar Radiation based on Photovoltaic Cells - by strada916 - 12-08-2015, 14:23
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 12-08-2015, 14:45
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 12-08-2015, 16:20
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 12-08-2015, 19:07
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 13-08-2015, 09:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 13-08-2015, 15:48
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 19-08-2015, 00:53
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 19-08-2015, 16:51
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 29-08-2015, 04:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by seth22 - 05-09-2015, 09:12
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 06-09-2015, 16:48
RE: Measuring Solar Radiation based on Photovoltaic Cells - by laulau - 22-01-2016, 14:11
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 23-01-2016, 13:51
RE: Measuring Solar Radiation based on Photovoltaic Cells - by laulau - 23-01-2016, 17:39
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllanG - 23-01-2016, 17:56
RE: Measuring Solar Radiation based on Photovoltaic Cells - by laulau - 24-01-2016, 10:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 24-01-2016, 11:05
RE: Measuring Solar Radiation based on Photovoltaic Cells - by laulau - 30-01-2016, 11:13
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 30-01-2016, 21:39
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 12-02-2016, 00:28
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 13-02-2016, 21:10
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 13-02-2016, 22:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 14-02-2016, 00:07
RE: Measuring Solar Radiation based on Photovoltaic Cells - by JT118 - 14-02-2016, 16:25
RE: Measuring Solar Radiation based on Photovoltaic Cells - by meteobreda - 04-04-2016, 16:20
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 07-04-2016, 11:21
RE: Measuring Solar Radiation based on Photovoltaic Cells - by meteobreda - 07-04-2016, 21:15
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 07-04-2016, 22:06
RE: Measuring Solar Radiation based on Photovoltaic Cells - by zitoune - 17-08-2016, 16:36
RE: Measuring Solar Radiation based on Photovoltaic Cells - by zitoune - 18-08-2016, 09:58
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 18-08-2016, 10:52
RE: Measuring Solar Radiation based on Photovoltaic Cells - by zitoune - 18-08-2016, 11:12
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 18-08-2016, 23:29
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 26-06-2017, 20:58
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 27-08-2017, 00:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 27-08-2017, 09:28
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 27-08-2017, 11:01
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 27-08-2017, 20:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 27-08-2017, 00:48
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 27-08-2017, 02:36
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 27-08-2017, 20:04
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 27-08-2017, 23:09
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 27-08-2017, 23:16
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 27-08-2017, 23:28
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 28-08-2017, 00:59
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 28-08-2017, 14:33
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 28-08-2017, 17:25
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 30-08-2017, 02:02
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 31-08-2017, 11:00
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 31-08-2017, 04:36
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 31-08-2017, 15:46
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 31-08-2017, 22:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 01-09-2017, 00:07
RE: Measuring Solar Radiation based on Photovoltaic Cells - by jgveill - 01-12-2017, 20:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by f4aii - 01-12-2017, 07:13
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 01-12-2017, 11:03
RE: Measuring Solar Radiation based on Photovoltaic Cells - by f4aii - 01-12-2017, 13:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 01-12-2017, 21:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 19-07-2019, 14:34
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hornychz - 19-07-2019, 16:11
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 19-07-2019, 16:38
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hornychz - 19-07-2019, 22:36
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 22-07-2019, 12:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 26-07-2019, 10:16
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hornychz - 27-07-2019, 15:01
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 29-07-2019, 11:29
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 26-07-2019, 13:43
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Aggotrom - 26-07-2019, 16:01
RE: Measuring Solar Radiation based on Photovoltaic Cells - by HF_ATL - 18-08-2019, 21:37
RE: Measuring Solar Radiation based on Photovoltaic Cells - by AllyCat - 18-08-2019, 22:56
RE: Measuring Solar Radiation based on Photovoltaic Cells - by uncle_bob - 20-08-2019, 01:14
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 18-08-2019, 22:25
RE: Measuring Solar Radiation based on Photovoltaic Cells - by SSHEEHY - 07-03-2021, 20:27
RE: Measuring Solar Radiation based on Photovoltaic Cells - by hornychz - 08-03-2021, 00:46
RE: Measuring Solar Radiation based on Photovoltaic Cells - by HF_ATL - 18-08-2019, 23:37
RE: Measuring Solar Radiation based on Photovoltaic Cells - by HF_ATL - 20-08-2019, 08:57
RE: Measuring Solar Radiation based on Photovoltaic Cells - by Werk_AG - 08-03-2021, 05:46



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