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Measuring Solar Radiation based on Photovoltaic Cells

Happy to have found this thread today as I was looking to have an inexpensive way to measure sun irradiance.  I looked for cheap pyranometer but the cheapest one is way too expensive for a weather station built just for fun.  

Looking at this project, the most difficult part is certainly the low voltage output and the need to have an opamp.  Somewhere in the thread, someone (alan I think) came with the idea to use a panel with more cells.  I think the real benefits were not seen.  The graph shown on the thread's first page is for one cell giving 0.5 to 0.6 volts.  Uncle_bob calculations are based on that : one cell solar panel.  If you use more cells you multiply the voltage by the number of cells, current being the same, which allows to get rid of the opamp. 

To give an idea of the values we could get with 10 cells solar panel, target voltage is then 1,6 volts.  So for 1600 W /m2 we now have 1600 mv or 1 mv /w / m2 (10 times lower).  With arduino internal ADC, this gives 4.88 W / m2 as the smaller step (again 10 time better than original design), which is quite good and really easy to do. Using 2 resistances for shunt to make a voltage divider (total becomes 17,33 ohms) we could use the 1,1 v arduino ref voltage and get 1,07 W /m2 as the smaller step and again no opamp needed ... Too good in fact for other imprecision factors like no real good reference irradiance.  
 
Some time ago, to make tests for building a sun irradiance meter, I ordered a 10 cells panel which is a 5 volts solar panel. In fact this is a 2 times 10 cells to have higher power.  I can expect higher short circuit current. As expected, open voltage is 5 to 6 volts.  I will make calculations and test this but here's what I expect with this panel : 

Short curcuit current : 0,27 amp for 810 W /m2 (bad conditions for a test today so I took a nice irradiance number to facilitate calculations)
Shunt resistance : 3 ohms
Maximum irradiance : 1500 w / m2 (1000 would probably be better for Quebec)
Max voltage measured: 1500 mv
1500 W / m2 -> 1500 mv or 1 mv / W / m2 
arduino gives 4,88 mv / step -> 4,88 w / m2

Also, with arduino, there's an easy way to get better precision : 16 bits ADC which has 4 inputs to do other things (like wind direction which is analog output for me).  

J Guy
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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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