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DavidFrancis

Solar radiation

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I'm thinking of spending a few days trying to work out to what extent our heating  demand is affected by temperature, wind and possibly the sun.  (Not really a great period as the temperature looks set to be fairly constant over the next week.)


We only have a very simple weather station and it doesn't log anything so I was going to use the Weather Underground local stations, which provide some great data including average temperatures and average wind speeds.  One station nearby also logs solar radiation but doesn't provide a daily average, just a table with about 150 readings per day.

 

I'm not interested enough in our heating demand to manually work out a daily radiation figure.  Does any one know of a web site that gives day-by-day radiation figures on a pretty local basis?  Or does anyone know of a slick way to manipulate the Weather Undergound figures?

 

For an example, see here:

https://www.wunderground.com/personal-weather-station/dashboard?ID=IENGLAND1342#history

 

Thanks

 

Edit: just tried following my own link and it takes you to the "Graphs" view.  You need to click on the "Table" tab below the Summary box to see the data in figures.

Edited by DavidFrancis

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We've discussed this here from time to time and on eBuild.  IMO The easiest way to calculate the incident radiation is to use the PVGIS online calculator. You can either do this by window or wall face.  Just put in the area of glass and the elevation as 90° (or the roof angle if a roof window).  One of the columns in the calculated table gives the average incident radiation in kWhr/ day by month for your location and orientation.  The % that gets into the room varies according to reflective coating and type of glass but is typically over 50% unless you've got a specialist coating on your windows.

 

The numbers can be frightening if you've got a lot of glass.  In our case we have smallish cottage-style on SE / NW facing walls and we get an extra ~2.5 kWhr / day for about 5 months a year dropping to 0.5 2.5 kWhr / day in Dec/Jan.

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We have been down this road before haven't we.

 

This will give you the daily readings as a comma separated value file

https://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=IENGLAND1342&day=22&month=11&year=2016&graphspan=day&format=1

 

You can use a Firefox addon called DwownThemAll to download the complete series between dates.

Then merge the files in DOS (CMD prompt) using:

 

copy *.xxx alldailyfiles.csv

 

Where xxx is the file extension of the download files.

 

Then you need to clean those files up a bit to get rid of the headings.  Probably for the small data set just opening up in Excel and sorting/delete is as quick as any.

 

Then you are free to do your conditional averaging.

 

 

 

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Thanks Steamy/Nick.  Didn't realise you could do that.  I can manage a CSV file OK.

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Should end up with something like this:

Date Temp Temp Day Only Windspeed Windspeed Day Only Solar Solar Day Only
04/07/2016 16.3 17.4 2.1 1.8 161 229
05/07/2016 14.5 14.8 6.5 6.9 241 334
06/07/2016 15.3 16.0 3.2 3.8 172 230
07/07/2016 16.3 16.5 4.9 6.6 124 178
08/07/2016 16.3 16.6 13.7 18.5 197 286
09/07/2016 17.5 18.0 1.7 2.0 99 143
10/07/2016 17.4 17.9 6.0 7.8 168 245
11/07/2016 14.7 14.9 13.3 16.3 69 102
12/07/2016 13.9 14.3 1.7 1.8 158 224
13/07/2016 13.9 14.4 6.3 8.5 221 316
14/07/2016 14.3 15.1 4.5 5.4 223 318
15/07/2016 16.0 16.6 1.9 1.9 104 141
16/07/2016 16.5 16.6 9.4 9.6 188 280
17/07/2016 16.0 16.7 6.5 7.7 240 342
18/07/2016 19.7 21.6 0.8 1.1 256 369
19/07/2016 24.6 26.6 2.4 3.0 312 445
20/07/2016 21.2 20.7 5.2 6.4 234 308
21/07/2016 18.6 19.4 2.9 3.0 262 347
22/07/2016 18.7 20.0 2.4 3.0 189 283
23/07/2016 17.8 19.0 1.0 1.0 177 259
24/07/2016 18.0 18.9 2.3 2.4 106 157
25/07/2016 15.7 15.9 11.3 13.5 154 225
26/07/2016 16.7 17.3 7.5 9.3 158 238
27/07/2016 16.2 16.6 4.7 4.5 231 343
28/07/2016 15.6 16.3 3.4 4.1 125 187
29/07/2016 16.5 17.0 4.4 4.7 180 270
30/07/2016 15.0 15.6 4.5 5.7 158 235
31/07/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
01/08/2016 15.6 16.4 2.8 2.4 110 165
02/08/2016 17.1 18.0 3.7 3.4 88 133
03/08/2016 17.4 17.8 11.5 12.3 138 218
04/08/2016 16.2 16.7 17.1 14.7 162 254
05/08/2016 16.3 17.1 4.2 4.4 208 309
06/08/2016 18.8 19.8 4.4 5.1 210 315
07/08/2016 17.9 18.2 23.6 26.6 203 333
08/08/2016 15.2 15.8 17.0 14.5 220 340
09/08/2016 14.0 14.8 5.7 7.0 146 229
10/08/2016 13.5 14.0 5.6 6.6 98 160
11/08/2016 15.2 15.5 20.3 22.2 66 108
12/08/2016 17.0 17.4 19.2 20.2 172 272
13/08/2016 16.2 16.5 14.1 14.0 170 269
14/08/2016 15.8 16.6 1.4 1.3 145 230
15/08/2016 17.3 20.0 1.2 1.5 212 334
16/08/2016 18.6 20.8 3.5 3.7 221 352
17/08/2016 17.7 19.6 4.1 4.8 218 351
18/08/2016 18.7 20.8 5.1 5.7 190 305
19/08/2016 16.2 16.4 4.3 3.8 82 132
20/08/2016 16.0 16.6 10.1 9.1 110 178
21/08/2016 16.3 16.7 12.1 13.8 128 213
22/08/2016 17.6 18.2 6.9 9.8 96 158
23/08/2016 19.9 22.3 0.8 1.0 191 314
24/08/2016 17.3 18.6 1.0 1.6 194 315
25/08/2016 16.8 17.6 1.2 1.4 54 95
26/08/2016 16.6 17.8 8.9 11.8 201 331
27/08/2016 15.9 17.7 3.6 4.2 127 212
28/08/2016 16.9 17.9 1.9 2.0 151 255
29/08/2016 16.0 17.1 3.1 5.1 205 348
30/08/2016 16.9 18.8 2.4 3.4 115 197
31/08/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
01/09/2016 15.9 16.8 6.1 7.4 124 216
02/09/2016 16.2 17.1 9.2 13.9 140 243
03/09/2016 14.2 14.3 1.8 1.9 43 75
04/09/2016 15.8 16.7 8.3 8.4 142 254
05/09/2016 17.6 19.3 2.0 3.3 135 233
06/09/2016 20.4 21.8 3.0 4.8 107 189
07/09/2016 21.3 23.1 0.8 0.9 148 259
08/09/2016 17.2 17.2 8.1 13.4 124 228
09/09/2016 17.5 18.6 3.0 2.9 75 138
10/09/2016 14.1 15.0 1.6 1.4 118 215
11/09/2016 15.5 17.2 2.5 2.2 130 226
12/09/2016 18.1 19.7 3.4 4.0 80 140
13/09/2016 18.6 19.2 1.7 2.4 73 136
14/09/2016 20.2 22.4 6.0 9.6 151 274
15/09/2016 18.3 19.8 0.8 0.8 123 230
16/09/2016 15.4 15.7 6.0 8.1 127 238
17/09/2016 13.7 15.4 1.0 1.7 147 276
18/09/2016 8.5 8.8 0.2 0.6 16 55
19/09/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
20/09/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
21/09/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
22/09/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
23/09/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
24/09/2016 18.2 18.7 4.0 3.1 18 48
25/09/2016 14.0 14.7 8.6 16.1 113 226
26/09/2016 12.2 13.0 1.0 1.5 56 114
27/09/2016 14.9 16.0 5.9 10.1 96 189
28/09/2016 17.3 18.1 10.2 6.8 91 185
29/09/2016 14.8 15.0 29.6 36.1 85 172
30/09/2016 12.2 13.5 9.3 12.7 105 212
01/10/2016 10.8 12.4 2.4 3.8 54 110
02/10/2016 9.7 12.2 0.6 0.8 118 245
03/10/2016 11.2 13.9 2.4 2.7 110 229
04/10/2016 13.6 15.8 6.1 6.8 105 211
05/10/2016 13.7 15.2 11.2 12.9 114 235
06/10/2016 11.2 13.2 9.2 14.2 103 215
07/10/2016 12.3 13.4 4.1 4.3 56 121
08/10/2016 12.5 13.4 2.3 3.6 84 185
09/10/2016 10.6 12.0 2.8 3.0 71 151
10/10/2016 9.0 11.0 2.3 3.9 87 184
11/10/2016 9.5 11.0 6.3 8.2 62 135
12/10/2016 11.2 12.3 9.0 8.5 51 111
13/10/2016 9.8 10.8 7.7 10.3 52 116
14/10/2016 10.2 11.9 5.9 7.6 54 123
15/10/2016 10.4 12.2 2.1 1.9 72 162
16/10/2016 11.4 13.2 3.6 4.3 64 147
17/10/2016 11.8 12.8 6.1 10.0 62 144
18/10/2016 10.4 10.1 13.4 18.5 31 71
19/10/2016 11.1 11.9 2.4 2.4 70 156
20/10/2016 9.8 11.2 0.2 0.2 47 108
21/10/2016 8.3 9.7 0.3 0.4 64 131
22/10/2016 7.6 9.9 3.1 5.3 46 106
23/10/2016 8.2 10.0 8.4 13.7 37 91
24/10/2016 8.2 9.8 4.3 5.8 46 108
25/10/2016 9.3 10.3 1.3 2.0 37 88
26/10/2016 12.4 13.4 8.0 13.4 42 101
27/10/2016 13.0 13.8 11.9 20.9 27 66
28/10/2016 12.9 12.7 8.7 0.2 27 70
29/10/2016 13.0 13.4 1.2 1.0 22 56
30/10/2016 11.8 12.6 0.5 0.1 28 73
31/10/2016 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #### #DIV/0!
01/11/2016 8.0 10.2 1.6 3.8 36 92
02/11/2016 5.7 7.8 0.4 0.7 39 97
03/11/2016 6.9 7.4 1.5 0.5 14 37
04/11/2016 8.0 8.8 5.9 8.4 30 79
05/11/2016 5.6 6.5 2.2 3.6 28 71
06/11/2016 4.9 6.3 3.0 5.6 31 75
07/11/2016 3.6 5.1 1.2 2.2 32 75
08/11/2016 1.3 2.1 3.5 1.6 16 44
09/11/2016 3.7 4.5 3.1 0.7 21 66
10/11/2016 7.0 8.4 8.0 12.3 28 74
11/11/2016 4.3 5.3 2.6 2.0 25 66
12/11/2016 9.1 10.7 3.7 2.9 26 71
13/11/2016 8.5 8.7 0.8 1.3 24 65
14/11/2016 11.2 11.6 7.8 10.0 12 35
15/11/2016 11.2 11.9 10.1 3.3 27 73
16/11/2016 9.5 10.1 20.2 23.4 22 60
17/11/2016 6.5 6.7 17.7 13.0 17 47
18/11/2016 4.9 5.1 15.5 18.8 18 53
19/11/2016 4.2 4.8 5.3 7.4 14 41
20/11/2016 2.6 4.7 3.1 1.6 23 66
21/11/2016 3.5 4.6 14.5 20.7 5 15

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Yesterday looked like a grim day up your way.

Only 3 times brighter than night time :D

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