Solar radiation

[DavidFrancis]

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 November 22, 2016 by DavidFrancis

[TerryE]

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.

[SteamyTea]

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.

 

 

 

[DavidFrancis]

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

[SteamyTea]

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

[SteamyTea]

Yesterday looked like a grim day up your way.

Only 3 times brighter than night time