So, I took the usual consumption figures from some standard day in september.
Using that I am trying to evaluate pay back period.
current | | | | | | | Batteries only | | | | | | | Solar +Battery | | | | |
Period | rate p/kwh | consumption kwh | cost p | | | | Period | rate p/kwh | consumption kwh | cost p | | | | Period | rate p/kwh | consumption kwh | cost p | |
00:00 - 00:30 | 7.14 | 0.24 | 1.7136 | | | | 00:00 - 00:30 | 7.14 | 0.24 | 1.7136 | | | | 00:00 - 00:30 | 7.14 | 0.24 | 1.7136 | |
00:30 - 01:00 | 7.14 | 0.43 | 3.0702 | | | | 00:30 - 01:00 | 7.14 | 0.43 | 3.0702 | | | | 00:30 - 01:00 | 7.14 | 0.43 | 3.0702 | |
01:00 - 01:30 | 7.14 | 1.68 | 11.9952 | | | | 01:00 - 01:30 | 7.14 | 1.68 | 11.9952 | | | | 01:00 - 01:30 | 7.14 | 1.68 | 11.9952 | |
01:30 - 02:00 | 7.14 | 3.88 | 27.7032 | | | | 01:30 - 02:00 | 7.14 | 3.88 | 27.7032 | | | | 01:30 - 02:00 | 7.14 | 3.88 | 27.7032 | |
02:00 - 02:30 | 7.14 | 3.36 | 23.9904 | | | | 02:00 - 02:30 | 7.14 | 3.36 | 23.9904 | | | | 02:00 - 02:30 | 7.14 | 3.36 | 23.9904 | |
02:30 - 03:00 | 7.14 | 0.17 | 1.2138 | | | | 02:30 - 03:00 | 7.14 | 0.17 | 1.2138 | | | | 02:30 - 03:00 | 7.14 | 0.17 | 1.2138 | |
03:00 - 03:30 | 7.14 | 0.17 | 1.2138 | | | | 03:00 - 03:30 | 7.14 | 0.17 | 1.2138 | | | | 03:00 - 03:30 | 7.14 | 0.17 | 1.2138 | |
03:30 - 04:00 | 7.14 | 0.38 | 2.7132 | | | | 03:30 - 04:00 | 7.14 | 0.38 | 2.7132 | | | | 03:30 - 04:00 | 7.14 | 0.38 | 2.7132 | |
04:00 - 04:30 | 7.14 | 0.12 | 0.8568 | | | | 04:00 - 04:30 | 7.14 | 0.12 | 0.8568 | | | | 04:00 - 04:30 | 7.14 | 0.12 | 0.8568 | |
04:30 - 05:00 | 7.14 | 0.32 | 2.2848 | | | | 04:30 - 05:00 | 7.14 | 0.32 | 2.2848 | | | | 04:30 - 05:00 | 7.14 | 0.32 | 2.2848 | |
05:00 - 05:30 | 7.14 | 0.14 | 0.9996 | | | | 05:00 - 05:30 | 7.14 | 0.14 | 0.9996 | | | | 05:00 - 05:30 | 7.14 | 0.14 | 0.9996 | |
05:30 - 06:00 | 28.79 | 0.15 | 4.3185 | | | | 05:30 - 06:00 | 7.14 | 0.15 | 1.071 | | | | 05:30 - 06:00 | 7.14 | 0.15 | 1.071 | |
06:00 - 06:30 | 28.79 | 0.13 | 3.7427 | | | | 06:00 - 06:30 | 7.14 | 0.13 | 0.9282 | | | | 06:00 - 06:30 | 7.14 | 0.13 | 0.9282 | |
06:30 - 07:00 | 28.79 | 0.15 | 4.3185 | | | | 06:30 - 07:00 | 7.14 | 0.15 | 1.071 | | | | 06:30 - 07:00 | 7.14 | 0.15 | 1.071 | |
07:00 - 07:30 | 28.79 | 0.18 | 5.1822 | | | | 07:00 - 07:30 | 7.14 | 0.18 | 1.2852 | | | | 07:00 - 07:30 | 7.14 | 0.18 | 1.2852 | |
07:30 - 08:00 | 28.79 | 0.17 | 4.8943 | | | | 07:30 - 08:00 | 7.14 | 0.17 | 1.2138 | | | | 07:30 - 08:00 | 7.14 | 0.17 | 1.2138 | |
08:00 - 08:30 | 28.79 | 0.14 | 4.0306 | | | | 08:00 - 08:30 | 7.14 | 0.14 | 0.9996 | | | | 08:00 - 08:30 | 7.14 | 0.14 | 0.9996 | |
08:30 - 09:00 | 28.79 | 0.11 | 3.1669 | | | | 08:30 - 09:00 | 7.14 | 0.11 | 0.7854 | | | | 08:30 - 09:00 | 7.14 | 0.11 | 0.7854 | |
09:00 - 09:30 | 28.79 | 0.12 | 3.4548 | | | | 09:00 - 09:30 | 7.14 | 0.12 | 0.8568 | | | | 09:00 - 09:30 | 0 | 0.12 | 0 | |
09:30 - 10:00 | 28.79 | 0.13 | 3.7427 | | | | 09:30 - 10:00 | 7.14 | 0.13 | 0.9282 | | | | 09:30 - 10:00 | 0 | 0.13 | 0 | |
10:00 - 10:30 | 28.79 | 0.25 | 7.1975 | | | | 10:00 - 10:30 | 7.14 | 0.25 | 1.785 | | | | 10:00 - 10:30 | 0 | 0.25 | 0 | |
10:30 - 11:00 | 28.79 | 0.14 | 4.0306 | | | | 10:30 - 11:00 | 7.14 | 0.14 | 0.9996 | | | | 10:30 - 11:00 | 0 | 0.14 | 0 | |
11:00 - 11:30 | 28.79 | 0.11 | 3.1669 | | | | 11:00 - 11:30 | 7.14 | 0.11 | 0.7854 | | | | 11:00 - 11:30 | 0 | 0.11 | 0 | |
11:30 - 12:00 | 28.79 | 0.12 | 3.4548 | | | | 11:30 - 12:00 | 7.14 | 0.12 | 0.8568 | | | | 11:30 - 12:00 | 0 | 0.12 | 0 | |
12:00 - 12:30 | 28.79 | 0.09 | 2.5911 | | | | 12:00 - 12:30 | 7.14 | 0.09 | 0.6426 | | | | 12:00 - 12:30 | 0 | 0.09 | 0 | |
12:30 - 13:00 | 28.79 | 0.07 | 2.0153 | | | | 12:30 - 13:00 | 7.14 | 0.07 | 0.4998 | | | | 12:30 - 13:00 | 0 | 0.07 | 0 | |
13:00 - 13:30 | 28.79 | 0.09 | 2.5911 | | | | 13:00 - 13:30 | 7.14 | 0.09 | 0.6426 | | | | 13:00 - 13:30 | 0 | 0.09 | 0 | |
13:30 - 14:00 | 28.79 | 0.08 | 2.3032 | | | | 13:30 - 14:00 | 7.14 | 0.08 | 0.5712 | | | | 13:30 - 14:00 | 0 | 0.08 | 0 | |
14:00 - 14:30 | 28.79 | 0.1 | 2.879 | | | | 14:00 - 14:30 | 7.14 | 0.1 | 0.714 | | | | 14:00 - 14:30 | 0 | 0.1 | 0 | |
14:30 - 15:00 | 28.79 | 0.08 | 2.3032 | | | | 14:30 - 15:00 | 7.14 | 0.08 | 0.5712 | | | | 14:30 - 15:00 | 0 | 0.08 | 0 | |
15:00 - 15:30 | 28.79 | 0.08 | 2.3032 | | | | 15:00 - 15:30 | 7.14 | 0.08 | 0.5712 | | | | 15:00 - 15:30 | 0 | 0.08 | 0 | |
15:30 - 16:00 | 28.79 | 0.08 | 2.3032 | | | | 15:30 - 16:00 | 7.14 | 0.08 | 0.5712 | | | | 15:30 - 16:00 | 0 | 0.08 | 0 | |
16:00 - 16:30 | 28.79 | 0.07 | 2.0153 | | | | 16:00 - 16:30 | 7.14 | 0.07 | 0.4998 | | | | 16:00 - 16:30 | 0 | 0.07 | 0 | |
16:30 - 17:00 | 28.79 | 0.1 | 2.879 | | | | 16:30 - 17:00 | 7.14 | 0.1 | 0.714 | | | | 16:30 - 17:00 | 0 | 0.1 | 0 | |
17:00 - 17:30 | 28.79 | 0.08 | 2.3032 | | | | 17:00 - 17:30 | 7.14 | 0.08 | 0.5712 | | | | 17:00 - 17:30 | 0 | 0.08 | 0 | |
17:30 - 18:00 | 28.79 | 0.29 | 8.3491 | | | | 17:30 - 18:00 | 7.14 | 0.29 | 2.0706 | | | | 17:30 - 18:00 | 0 | 0.29 | 0 | |
18:00 - 18:30 | 28.79 | 0.17 | 4.8943 | | | | 18:00 - 18:30 | 7.14 | 0.17 | 1.2138 | | | | 18:00 - 18:30 | 0 | 0.17 | 0 | |
18:30 - 19:00 | 28.79 | 0.12 | 3.4548 | | | | 18:30 - 19:00 | 7.14 | 0.12 | 0.8568 | | | | 18:30 - 19:00 | 0 | 0.12 | 0 | |
19:00 - 19:30 | 28.79 | 0.15 | 4.3185 | | | | 19:00 - 19:30 | 7.14 | 0.15 | 1.071 | | | | 19:00 - 19:30 | 0 | 0.15 | 0 | |
19:30 - 20:00 | 28.79 | 1.39 | 40.0181 | | | | 19:30 - 20:00 | 7.14 | 1.39 | 9.9246 | | | | 19:30 - 20:00 | 0 | 1.39 | 0 | |
20:00 - 20:30 | 28.79 | 0.25 | 7.1975 | | | | 20:00 - 20:30 | 7.14 | 0.25 | 1.785 | | | | 20:00 - 20:30 | 0 | 0.25 | 0 | |
20:30 - 21:00 | 28.79 | 0.23 | 6.6217 | | | | 20:30 - 21:00 | 7.14 | 0.23 | 1.6422 | | | | 20:30 - 21:00 | 0 | 0.23 | 0 | |
21:00 - 21:30 | 28.79 | 0.21 | 6.0459 | | | | 21:00 - 21:30 | 7.14 | 0.21 | 1.4994 | | | | 21:00 - 21:30 | 0 | 0.21 | 0 | |
21:30 - 22:00 | 7.14 | 4.05 | 28.917 | | | | 21:30 - 22:00 | 7.14 | 4.05 | 28.917 | | | | 21:30 - 22:00 | 0 | 4.05 | 0 | |
22:00 - 22:30 | 7.14 | 3.96 | 28.2744 | | | | 22:00 - 22:30 | 7.14 | 3.96 | 28.2744 | | | | 22:00 - 22:30 | 0 | 3.96 | 0 | |
22:30 - 23:00 | 7.14 | 3.95 | 28.203 | | | | 22:30 - 23:00 | 7.14 | 3.95 | 28.203 | | | | 22:30 - 23:00 | 0 | 3.95 | 0 | |
23:00 - 23:30 | 7.14 | 4.1 | 29.274 | | | | 23:00 - 23:30 | 7.14 | 4.1 | 29.274 | | | | 23:00 - 23:30 | 0 | 4.1 | 0 | |
23:30 - 00:00 | 7.14 | 4.17 | 29.7738 | | | | 23:30 - 00:00 | 7.14 | 4.17 | 29.7738 | | | | 23:30 - 00:00 | 7.14 | 4.17 | 29.7738 | |
| | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | difference | | | | | | | difference |
| | Cost per day | £ 3.84 | £ - | | | | | Cost per day | £ 2.62 | -£ 1.22 | | | | | Cost per day | £ 1.15 | -£ 1.48 |
| | Yearly | £ 1,402.64 | £ - | | | | | Yearly | £ 957.74 | -£ 444.90 | | | | | Yearly | £ 419.32 | -£ 538.42 |
| | monthly | £ 115.29 | £ - | | | | | monthly | £ 78.72 | -£ 36.57 | | | | | monthly | £ 34.46 | -£ 44.25 |
taking into account that I would do loads of miles and need some charging of 30 kwh per night
Batteries only would save me ~444 a year (or ~36.6 gbp a month)
Solar + batteries would be 538 a year of savings (or 44 gbp a month)
I get basically 10-20 gbp a month difference max (let's say I cannot charge during the day as I am away) between solar and batteries only (relying on off-peak rate only).
just trying to understand the maths here... as my solar pack with batteries would be ~12k, let's say, pay off in 6 years - 2k a year or 166 a month
overall, 12k investment in the system would mean that in 45 gbp savings I need 20 years pay off :/ do I miss something here or it makes no sense in general?