diffrent prices yet EXACT same usage

NittyGritty

hi ive used a few sites below to compare some tariffs, I,m liking the npowers Price Protector March 2017
I,m currently on scotish power energy online saver 20 which ends soon,
heres where the problems/diffrences start, I have entered the exact same usage over the year 14000 all electric (no gas) (4000 day units 10000 night units over the year) on all sites below on economy 7, using national average 54% in options on all

1.uswitch =£1,406.03 Npowers Price Protector March 2017
2.confused.com =£1,698.73 Npowers Price Protector March 2017
3.moneysupermarket = £1,706 Npowers Price Protector March 2017

I would list more but they are all over the place
my question is why am I getting completely different prices, even tho I enter the EXACT same figures in all?
on the above sites, ive come to the conclusion that they are not all what they seem to be, each site seems to be completely different and as such , should they be trusted with their prices/outcomes?

notbritishgas

Think I have found your problem.
I have just put your figures in Confused and uswitch.
You say you put night usage of 54% into confused, but in uswitch you must have put the actual kwh, ie 4000 and 10000.
Now your night usage is about 71% (very good).

So if you put the nearest one, 70% into confused you get a similar result. I think you must be in my area,east mids, as the figures are the same as yours, £1406 in uswitch and £1431 in confused.
The slight difference accounted for by having to use 70% not 71%.

NittyGritty

ahhh, thanks for that, yes we in east mids area

Cardew

What do you mean by "using national average 54% in options on all"?

14,000kWh total consumption with 10,000kWh off-peak means 71.4% on off-peak.

Are you saying that you have used the figure of 54%?

On energyhelpline for Npowers Price Protector March 2017 in my area(midlands) 70% E7 usage* gives a figure of £1,511. Using 55% it is £1,803.

Because of the huge difference between off-peak and Peak prices(6.132p/kWH and 20.024p/kWh) a different way calculating percentages on off-peak can make a big difference. Could it be that the websites are using different way?(despite you entering correctly)

Also Npower's method of calculating discount at end of 12 months is to be 'outlawed'. Could this be another factor?

* Energyhelpline only have 5% increments.

edit. Post crossed with Notbritishgas - great minds etc!