How we calculated whole annual electrical energy value for no photo voltaic (electrical energy solely) on Versatile Octopus
We began by utilizing a complete annual consumption determine of three,500kWh. That is an instance determine used, based mostly on customary MCS calculations (with the shopper at dwelling half the day) and can also be the imply, non-population weighted British electrical energy consumption in response to UK Authorities statistics
To calculate how a lot it prices to eat 3,500kWh of electrical energy, we took the January 2025 regional common worth cap figures from Ofgem, that are:
Common Unit Fee – 24.86p/kWh
Common Standing Cost – 60.97p/day
The overall value of electrical energy, for a property with no photo voltaic panels, with the above assumptions works out to be:
Value of Imported Electrical energy + Standing Cost (3,500kWh x 24.86p) + (60.97p x 365) = £1,093
How we calculated whole annual electrical energy value and financial savings for a property with a ten photo voltaic panel system, no battery storage. On Versatile Octopus for import, and Fastened Outgoing Octopus for export
We took the identical whole annual consumption determine as above, and assume the ten x 445W panels generate, yearly, 4,045kWh of electrical energy.
That is based mostly on a property with photo voltaic panels on a south dealing with roof with a 35º pitch and effectivity issue of 909 (that is roughly the UK common).
Primarily based on MCS standardised calculations and steering, a property with whole annual consumption between 3,500 – 3,999 kWh, and a complete annual technology between 3,900 – 4,199kWh, with a panel solely system, self consumes 23% of the vitality generated. This works out to be: 4,045kWh x 22% = 930kWh
This implies the rest (4,045kWh – 930kWh) of three,115kWh is assumed to be exported again to the grid.
We assume the exported vitality is paid for at a price of 15p/kWh. That is our Jan 2025 Fastened Outgoing Tariff export price.
Since whole annual consumption is assumed to be 3,500kWh, of which 930kWh is consumed from electrical energy generated by the photo voltaic panels, the rest (2,570kWh) must be imported from the grid.
To calculate the overall annual electrical energy value of this property, we’ll once more use the January 2025 common Ofgem worth cap figures. To recap, these are 24.86p/kWh unit price, and a 60.97p/day standing cost, and the talked about Outgoing Octopus tariff price of 15p/kWh.
The overall annual electrical energy value works out to be:
Value of imported electrical energy + standing cost – (Export Financial savings)
(2,570kWh x 24.86p) + (60.97p x 365) – (3,115kWh x 15p) = £394
Versus a property with no photo voltaic panel system put in, the overall financial savings are:
Whole Annual Elec invoice of property with no photo voltaic – Whole Annual Elec invoice of property with photo voltaic
£1,093 – £394 = £698 (64% saved)
How we calculated whole annual electrical energy value and financial savings for a property with a ten panel system, 5kWh battery storage. On Versatile Octopus for import, and Outgoing Octopus for export
Primarily based on MCS standardised calculations and steering, a property with whole annual consumption between 3,500 – 3,999 kWh, and a complete annual technology between3,900 – 4,199kWh, with a ten photo voltaic panel system AND a battery storage with 4.1 – 5.1kWh usable capability is predicted to self eat 57% of the vitality generated.
Assuming the identical whole annual technology as above, the brand new self consumed electrical energy is:
4,045kWh x 57% = 2,306kWh
Which means the rest (1,739kWh) is exported to the grid.
Assuming the identical whole annual consumption as above, the brand new imported electrical energy is:
Whole Annual Consumption – Self Consumption: 3.500kWh – 2,306kWh = 1,194kWh
Assuming the identical unit price, standing cost and export charges as above, the overall annual electrical energy value works out to be:
Imported electrical energy + standing cost – (Export Financial savings)
(1,194kWh x 24.86p) + (60.97p x 365) – (2,306kWh x 15p) = £259
Versus a property with no photo voltaic panel system put in, the overall financial savings listed here are:
Whole Annual Elec invoice of property with no photo voltaic – Whole Annual Elec invoice of property with photo voltaic.
£1,093 – £259 = £834 (76% saved)
How we calculated whole annual electrical energy value and financial savings for a property with a ten panel system, 5kWh battery storage. On Octopus Flux for import and export.
All assumptions stay the identical as above, aside from the import price, export price and standing cost, because the tariff has modified right here.
As of January 2025, we now have used a weighted common import price of 20.58p/kWh, a weighted common export price of 16.22p/kWh, and a median standing cost of 58.93p/day.
The weighted import and export charges have been obtained by wanting on the common utilization patterns for purchasers on the Octopus Flux tariff.
With all different assumptions remaining the identical, the overall annual electrical energy invoice for this property works out to be:
Value of Imported electrical energy + standing cost – (export financial savings)
(1,194kWh x 20.58p) + (58.93p x 365) – (2,306kWh x 16.22p) = £179
Versus a property with no photo voltaic panel system put in, the overall financial savings listed here are:
Whole Annual Elec invoice of property with no photo voltaic – Whole Annual Elec invoice of property with photo voltaic
£1,093 – £179 = £914 (84% saved)
How we calculated whole annual electrical energy value and financial savings for a property with a ten panel system, 5kWh battery storage. On Clever Octopus Flux for import and export.
We first took our common Jan 2025 Clever Octopus Flux charges (in p/kWh) that are:
Import / Export
Peak 29.83p / 29.83p
Day price 22.37p / 22.37p
We then used this to calculate the weighted common import and export price. The weighted import and export charges have been obtained by wanting on the utilization patterns for purchasers on the Clever Octopus Flux tariff.
This works out to be:
Weighted import price: 22.89p
Weighted export price: 26.99p
The common standing cost on the IOF tariff for Jan 2025 is 58.93p per day.
The annual invoice was calculated as:
Value of Imported electrical energy + standing cost – (export financial savings)
(1,194kWh x 22.89p) + (58.93p x 365) – (1,739kWh x 26.99p) = £19
This can be a saving of £1,074 or 98% (£1,093 – £19)
