Solar panels and battery - any real world reccomendations?

Peteronthesouthcoast · 26 Dec 2022 at 11:41

Mercenary Keyboard Warrior said:
BTW the impact of heat is detailed on your panels spec sheet

It is a number that you add or subtract from typically 20-25c, its not that much, but in effect a say 400w panel may perform like a 425w say at 5c and a 375w at 45c

Mine are 405w -0.37% per c (from 25) so 10 degrees higher would lose 3.7%

Never saw that when we purchased ours originally. Sanyo did say that their "unique HIT" panels resisted the effects of heat better than non HIT panels which was basically everyone else. Wonder how hot panels get when it is a hot day of say 35.

Key to our going off grid date (which is the 20th Jan) is the angle of the sun.

Look at this below. Column 3 is the peak angle of the sun. The only figures I could find years ago were for London, so we have used those. We are about 50 miles further south.

Once we get to 18.5 degrees, I think that we should be able to survive on our panels and batteries. Yes the hours of daylight get longer which helps. We have logged the 5th January and the 17th January as perfect days. The solar increase is way beyond the proportional increase in the length of the day. By the time we get to February, we are most likely to have the car and house batteries looking quite healthy.

14	Dec-21	7h 52m 33s	15.3°	1.0	1.4	1.5	44093.8	2.9	3.9
15	Dec-21	7h 51m 49s	15.3°	1.0	0.8	0.6	44094.8	1.4	2.4
16	Dec-21	7h 51m 12s	15.2°	0.5	0.8	0.7	44095.3	1.5	2.0
17	Dec-21	7h 50m 42s	15.2°	2.4	1.9	3.8	44097.7	5.7	8.1
18	Dec-21	7h 50m 18s	15.2°	6.8	2.4	10.1	44104.5	12.5	19.3
19	Dec-21	7h 50m 00s	15.1°	3.4	2.3	4.8	44107.9	7.1	10.5
20	Dec-21	7h 49m 49s	15.1°	0.7	1.1	1.1	44108.6	2.2	2.9
21	Dec-21	7h 49m 44s	15.1°	1.4	1.8	2.2	44110.0	4.0	5.4
22	Dec-21	7h 49m 46s	15.1°	2.0	2.3	2.9	44112.0	5.2	7.2
23	Dec-21	7h 49m 54s	15.1°	0.2	0.2	0.2	44112.2	0.4	0.6
24	Dec-21	7h 50m 09s	15.2°	1.3	1.4	1.4	44113.5	2.8	4.1
25	Dec-21	7h 50m 30s	15.2°	0.8	1.0	1.0	44114.3	2.0	2.8
26	Dec-21	7h 50m 58s	15.2°	1.6	1.2	2.4	44115.9	3.6	5.2
27	Dec-21	7h 51m 33s	15.3°	0.9	0.9	1.2	44116.8	2.1	3.0
28	Dec-21	7h 52m 14s	15.3°	2.9	2.3	4.3	44119.7	6.6	9.5
29	Dec-21	7h 53m 01s	15.4°	1.3	1.1	1.8	44121.0	2.9	4.2
30	Dec-21	7h 53m 54s	15.4°	0.2	0.0	0.3	44121.2	0.3	0.5
31	Dec-21	7h 54m 54s	15.5°	0.4	0.1	0.5	44121.6	0.6	1.0
1	Jan-22	7h 56m 00s	15.6°	1.9	1.9	2.6	44123.5	4.5	6.4
2	Jan-22	7h 57m 12s	15.7°	1.3	1.4	1.8	44124.8	3.2	4.5
3	Jan-22	7h 58m 30s	15.8°	1.3	1.6	1.8	44126.1	3.4	4.7
4	Jan-22	7h 59m 53s	15.9°	1.3	1.2	1.8	44127.4	3.0	4.3
5	Jan-22	8h 01m 23s	16.0°	11.6	6.1	16.6	44139.0	22.7	34.3
6	Jan-22	8h 02m 58s	16.1°	1.1	1.4	1.4	44140.1	2.8	3.9
7	Jan-22	8h 04m 39s	16.2°	2.9	3.2	3.9	44143.0	7.1	10.0
8	Jan-22	8h 06m 25s	16.3°	0.3	0.5	0.2	44143.3	0.7	1.0
9	Jan-22	8h 08m 17s	16.5°	9.3	5.8	12.6	44152.6	18.4	27.7
10	Jan-22	8h 10m 14s	16.6°	0.9	1.1	1.3	44153.5	2.4	3.3
11	Jan-22	8h 12m 16s	16.8°	0.6	0.9	0.7	44154.1	1.6	2.2
12	Jan-22	8h 14m 23s	16.9°	12.6	6.1	16.9	44166.7	23.0	35.6
13	Jan-22	8h 16m 35s	17.1°	13.8	6.8	18.4	44180.5	25.2	39.0
14	Jan-22	8h 18m 51s	17.3°	14.0	6.8	18.4	44194.5	25.2	39.2
15	Jan-22	8h 21m 12s	17.5°	2.8	3.0	3.9	44197.3	6.9	9.7
16	Jan-22	8h 23m 38s	17.7°	8.2	4.1	10.6	44205.5	14.7	22.9
17	Jan-22	8h 26m 08s	17.9°	14.6	7.0	18.8	44220.1	25.8	40.4
18	Jan-22	8h 28m 41s	18.1°	4.5	2.9	6.0	44224.6	8.9	13.4
19	Jan-22	8h 31m 20s	18.3°	2.4	2.0	3.2	44227.0	5.2	7.6
20	Jan-22	8h 34m 02s	18.5°	14.1	7.5	18.3	44241.1	25.8	39.9
21	Jan-22	8h 36m 48s	18.7°	6.6	6.5	9.0	44247.7	15.5	22.1
22	Jan-22	8h 39m 38s	18.9°	1.7	2.0	2.2	44249.4	4.2	5.9
23	Jan-22	8h 42m 31s	19.2°	0.7	1.0	1.0	44250.1	2.0	2.7
24	Jan-22	8h 45m 28s	19.4°	0.8	1.1	1.2	44250.9	2.3	3.1
25	Jan-22	8h 48m 28s	19.6°	0.5	0.8	0.7	44251.4	1.5	2.0
26	Jan-22	8h 51m 31s	19.9°	5.1	2.7	6.4	44256.5	9.1	14.2
27	Jan-22	8h 54m 37s	20.1°	2.8	1.7	3.0	44259.3	4.7	7.5
28	Jan-22	8h 57m 46s	20.4°	9.6	6.0	12.5	44268.9	18.5	28.1
29	Jan-22	9h 00m 58s	20.7°	4.9	4.1	6.5	44273.8	10.6	15.5
30	Jan-22	9h 04m 13s	20.9°	14.8	8.2	19.3	44288.6	27.5	42.3
31	Jan-22	9h 07m 30s	21.2°	5.3	2.9	6.7	44293.9	9.6	14.9

Mercenary Keyboard Warrior · 26 Dec 2022 at 12:13

Peteronthesouthcoast said:
Never saw that when we purchased ours originally. Sanyo did say that their "unique HIT" panels resisted the effects of heat better than non HIT panels which was basically everyone else. Wonder how hot panels get when it is a hot day of say 35.

Key to our going off grid date (which is the 20th Jan) is the angle of the sun.

Look at this below. Column 3 is the peak angle of the sun. The only figures I could find years ago were for London, so we have used those. We are about 50 miles further south.

Once we get to 18.5 degrees, I think that we should be able to survive on our panels and batteries. Yes the hours of daylight get longer which helps. We have logged the 5th January and the 17th January as perfect days. The solar increase is way beyond the proportional increase in the length of the day. By the time we get to February, we are most likely to have the car and house batteries looking quite healthy.

14
Dec-21 7h 52m 33s 15.3°
1.0
1.4
1.5
44093.8
2.9
3.9
15
Dec-21 7h 51m 49s 15.3°
1.0
0.8
0.6
44094.8
1.4
2.4
16
Dec-21 7h 51m 12s 15.2°
0.5
0.8
0.7
44095.3
1.5
2.0
17
Dec-21 7h 50m 42s 15.2°
2.4
1.9
3.8
44097.7
5.7
8.1
18
Dec-21 7h 50m 18s 15.2°
6.8
2.4
10.1
44104.5
12.5
19.3
19
Dec-21 7h 50m 00s 15.1°
3.4
2.3
4.8
44107.9
7.1
10.5
20
Dec-21 7h 49m 49s 15.1°
0.7
1.1
1.1
44108.6
2.2
2.9
21
Dec-21 7h 49m 44s 15.1°
1.4
1.8
2.2
44110.0
4.0
5.4
22
Dec-21 7h 49m 46s 15.1°
2.0
2.3
2.9
44112.0
5.2
7.2
23
Dec-21 7h 49m 54s 15.1°
0.2
0.2
0.2
44112.2
0.4
0.6
24
Dec-21 7h 50m 09s 15.2°
1.3
1.4
1.4
44113.5
2.8
4.1
25
Dec-21 7h 50m 30s 15.2°
0.8
1.0
1.0
44114.3
2.0
2.8
26
Dec-21 7h 50m 58s 15.2°
1.6
1.2
2.4
44115.9
3.6
5.2
27
Dec-21 7h 51m 33s 15.3°
0.9
0.9
1.2
44116.8
2.1
3.0
28
Dec-21 7h 52m 14s 15.3°
2.9
2.3
4.3
44119.7
6.6
9.5
29
Dec-21 7h 53m 01s 15.4°
1.3
1.1
1.8
44121.0
2.9
4.2
30
Dec-21 7h 53m 54s 15.4°
0.2
0.0
0.3
44121.2
0.3
0.5
31
Dec-21 7h 54m 54s 15.5°
0.4
0.1
0.5
44121.6
0.6
1.0
1
Jan-22 7h 56m 00s 15.6°
1.9
1.9
2.6
44123.5
4.5
6.4
2
Jan-22 7h 57m 12s 15.7°
1.3
1.4
1.8
44124.8
3.2
4.5
3
Jan-22 7h 58m 30s 15.8°
1.3
1.6
1.8
44126.1
3.4
4.7
4
Jan-22 7h 59m 53s 15.9°
1.3
1.2
1.8
44127.4
3.0
4.3
5
Jan-22 8h 01m 23s 16.0°
11.6
6.1
16.6
44139.0
22.7
34.3
6
Jan-22 8h 02m 58s 16.1°
1.1
1.4
1.4
44140.1
2.8
3.9
7
Jan-22 8h 04m 39s 16.2°
2.9
3.2
3.9
44143.0
7.1
10.0
8
Jan-22 8h 06m 25s 16.3°
0.3
0.5
0.2
44143.3
0.7
1.0
9
Jan-22 8h 08m 17s 16.5°
9.3
5.8
12.6
44152.6
18.4
27.7
10
Jan-22 8h 10m 14s 16.6°
0.9
1.1
1.3
44153.5
2.4
3.3
11
Jan-22 8h 12m 16s 16.8°
0.6
0.9
0.7
44154.1
1.6
2.2
12
Jan-22 8h 14m 23s 16.9°
12.6
6.1
16.9
44166.7
23.0
35.6
13
Jan-22 8h 16m 35s 17.1°
13.8
6.8
18.4
44180.5
25.2
39.0
14
Jan-22 8h 18m 51s 17.3°
14.0
6.8
18.4
44194.5
25.2
39.2
15
Jan-22 8h 21m 12s 17.5°
2.8
3.0
3.9
44197.3
6.9
9.7
16
Jan-22 8h 23m 38s 17.7°
8.2
4.1
10.6
44205.5
14.7
22.9
17
Jan-22 8h 26m 08s 17.9°
14.6
7.0
18.8
44220.1
25.8
40.4
18
Jan-22 8h 28m 41s 18.1°
4.5
2.9
6.0
44224.6
8.9
13.4
19
Jan-22 8h 31m 20s 18.3°
2.4
2.0
3.2
44227.0
5.2
7.6
20
Jan-22 8h 34m 02s 18.5°
14.1
7.5
18.3
44241.1
25.8
39.9
21
Jan-22 8h 36m 48s 18.7°
6.6
6.5
9.0
44247.7
15.5
22.1
22
Jan-22 8h 39m 38s 18.9°
1.7
2.0
2.2
44249.4
4.2
5.9
23
Jan-22 8h 42m 31s 19.2°
0.7
1.0
1.0
44250.1
2.0
2.7
24
Jan-22 8h 45m 28s 19.4°
0.8
1.1
1.2
44250.9
2.3
3.1
25
Jan-22 8h 48m 28s 19.6°
0.5
0.8
0.7
44251.4
1.5
2.0
26
Jan-22 8h 51m 31s 19.9°
5.1
2.7
6.4
44256.5
9.1
14.2
27
Jan-22 8h 54m 37s 20.1°
2.8
1.7
3.0
44259.3
4.7
7.5
28
Jan-22 8h 57m 46s 20.4°
9.6
6.0
12.5
44268.9
18.5
28.1
29
Jan-22 9h 00m 58s 20.7°
4.9
4.1
6.5
44273.8
10.6
15.5
30
Jan-22 9h 04m 13s 20.9°
14.8
8.2
19.3
44288.6
27.5
42.3
31
Jan-22 9h 07m 30s 21.2°
5.3
2.9
6.7
44293.9
9.6
14.9

Googling seems to indicate around 20c when its warm, so a 35 day would likely have panels running around 55.
Apparently the performance does drop off a cliff around 60c, although as ever with these things the tech has moved on in areas and they may be far less temp impacted than they once were

Ron-ski · 26 Dec 2022 at 15:28

Not a bad day, 7.31kWh here today, which means this December is better than last December.

Freefaller · 26 Dec 2022 at 15:39

12 here. Unfortunately not around to use it. But such is life!

Mercenary Keyboard Warrior · 26 Dec 2022 at 15:47

4.4 today, wasn't far off sunny most of the day
Just need the sun to gain a bit of height now, but gaining a minute a day in the afternoon so shouldnt be too long

Weather has one half decent day left in 22 according to BBC so unlikely to hit 3.3 average I had hoped for, at 2.8 right now

HungryHippos · 26 Dec 2022 at 15:55

6.7 kwh today which is fine, was a pretty good day here.

Just breached 100 kwh as well for December which I think is pretty good for this time of year, I won't be far off November in the end, but last month was very rainy.

Not much good on the Solcast though for the next week, it says only 29/12 will be much good.

Freefaller · 26 Dec 2022 at 16:12

100kWh for Dec is pretty amazing. I'm just about at 90.

Welshman · 26 Dec 2022 at 17:28

Just the 6.8kwhs for me today and breached the 81kwh prediction for december…..

gpuerrilla · 26 Dec 2022 at 18:13

2.9kWh a brave improvement on past few weeks.

Kot · 26 Dec 2022 at 18:36

Mercenary Keyboard Warrior said:
Q2 looks like since the longest daylight hours are in June
If you compare May to July
April to Sept etc you get a far more equal although still skewed graph

Typically UK weather I feel is better in the spring than the autumn.
If we get bad weather for the season it seems to happen far more frequently in late summer than early. (He says as an allotmenteer)

Considering June has the longest day in it lol its a no brainer, same reason December is pants with the shortest day

john_smith · 26 Dec 2022 at 19:09

9.2 today. 132 for Dec so far.

quickshot89 · 26 Dec 2022 at 19:22

4.2 today for me. I have a feeling my east panels are still missing direct sun ever so slightly or there is an installation fault.

redfist · 26 Dec 2022 at 19:23

10.9 today for myself with 121kWh for the month. Certainly used every kWh so far!

norm · 26 Dec 2022 at 23:32

Does anybody have any recommendations for a cheap solar panel setup for an allotment shed, to run a 230v inverter. Keeping in mind this would done on a minimal budget.

Would two 12v car batteries in series, a 24v charge controller, two 12v panels, inverter be all that's required?

Peteronthesouthcoast · 27 Dec 2022 at 08:10

norm said:
Does anybody have any recommendations for a cheap solar panel setup for an allotment shed, to run a 230v inverter. Keeping in mind this would done on a minimal budget.

Would two 12v car batteries in series, a 24v charge controller, two 12v panels, inverter be all that's required?

We have a caravan. It has a 100 watt solar panel and controller and a fuse all of which was wired in by the village idiot (myself). It keeps a 12 volt leisure battery topped up all year, and runs everything we need in the summer.

Total cost £100. It all comes down to how much power you want to draw down, and for how long, and if you can do this with 12volts. That is going to be the simplest and cheapest route. One thing to be aware of is that the equipment could grow legs overnight.

Welshman · 27 Dec 2022 at 12:44

Its chucking it down here, currently pulling 175watts, which is just about covering our base load……as long as that happens all day ill be happy with the lower usage from the grid

HungryHippos · 27 Dec 2022 at 14:53

Not a bad day got a few kwh today which was more than expected, I have some guests over later and battery is at 83% so I'm hopeful it will more or less see out the rest of today, though I'll need to smash the heating on for a bit to make sure people aren't cold.

BT decided to reboot my router overnight so I lost a few hours of data before 9AM, it seems that the wifi just doesn't work until I turn the wifi off and on again from the admin console after a reboot (good old IT fix).

Welshman · 27 Dec 2022 at 15:01

HungryHippos said:
Not a bad day got a few kwh today which was more than expected, I have some guests over later and battery is at 83% so I'm hopeful it will more or less see out the rest of today, though I'll need to smash the heating on for a bit to make sure people aren't cold.

BT decided to reboot my router overnight so I lost a few hours of data before 9AM, it seems that the wifi just doesn't work until I turn the wifi off and on again from the admin console after a reboot (good old IT fix).

I think some are stealing my sun lol

quickshot89 · 27 Dec 2022 at 15:42

0.6kw today

gpuerrilla · 27 Dec 2022 at 15:43