Help with equation/spreadsheet to find best tariff.

skycatcher

Hi,

I’m hoping some of you very smart spreadsheet guys can help me with a formula. I’m trying to analyse where the break even point is in terms of cost between various tariffs with SSE Gas NI.

The prices as of 1 Oct 22 are as follows :-

Quarterly Credit tariff

18.008p/kWh for the first 2000kWh ; 12.338p/kWh for each kWh over 2000kWh (incl VAT)

Min consumption charge (for equivalent 1678 kWh per year) = £302.17 - which is applicable on a pro rata basis if average daily consumption in that period is less than 4.6 kWh per day.

Prepayment Meter tariff

13.1p/kWh (incl VAT)

Note there is no minimum charge on prepayment.

It is the min charge element that I’m struggling to get my head around when looking at the best rate for me.

Thanks.

[Deleted User]

First thing to ask is do you use more than 4.6kWh of gas every day?

The minimum usage charge is just a ‘fine’ of about 83p per day for periods when you are not using that much (but it doesn’t say what ‘period’ they take the average usage over to work that out).

[Deleted User]

The other maths is pretty easy though.  The credit tariff will be cheaper at high use, the prepay at low use.  The crossover will be where the two prices are the same, so where:

(2000x0.18008)+((u-2000)x0.12338) = u x 0.131

skycatcher

[Deleted User] said:

First thing to ask is do you use more than 4.6kWh of gas every day?

Well the answer to that it's no in the summer months and yes in the winter. I did knock together a spreadsheet that worked during the winter but not the low usage periods so some quarters bills I had estimated correctly but summer ones were way off.

skycatcher

[Deleted User] said:

The other maths is pretty easy though.  The credit tariff will be cheaper at high use, the prepay at low use.  The crossover will be where the two prices are the same, so where:

(2000x0.18008)+((u-2000)x0.12338) = u x 0.131

Is it possible to have an equation which would estimate quarterly bills is where you haven't yet consumed 2000 units?

PennineAcute

I am not a spreadsheet fan, but this is my working out for when the prepay is cheaper.

0.131x < 2000*.18808 + (x-2000)*.12388
0.131x < 260.16 + 0.12388x
.00712x<112.24
x<15764

So, where your gas usage is >= 2000, the prepay will be cheaper when it is less than 15764 kWh

When your usage < 2000

0.131x < .18808x

prepay will always be cheaper < 2000 kWh

Is there a SC with the prepay?

skycatcher

Deleted_User said:

First thing to ask is do you use more than 4.6kWh of gas every day?

The minimum usage charge is just a ‘fine’ of about 83p per day for periods when you are not using that much (but it doesn’t say what ‘period’ they take the average usage over to work that out).

thanks sparky - their website says :- "Your account is subject to a charge for minimum consumption of 1,678 kWh per year which is applicable on a pro rata basis if average daily consumption in that period is less than 4.6 kWh per day."

skycatcher

PennineAcute said:

I am not a spreadsheet fan, but this is my working out for when the prepay is cheaper.

0.131x < 2000*.18808 + (x-2000)*.12388
0.131x < 260.16 + 0.12388x
.00712x<112.24
x<15764

So, where your gas usage is >= 2000, the prepay will be cheaper when it is less than 15764 kWh

When your usage < 2000

0.131x < .18808x

prepay will always be cheaper < 2000 kWh

Is there a SC with the prepay?

No SC with prepay....I agree with your break even point.

 My usage last year was 2626 (Aug 21- Aug 22) as I used a multi fuel stove last winter but with coal prices way up I'll proably use more gas this winter!

[Deleted User]

skycatcher said:

Deleted_User said:

First thing to ask is do you use more than 4.6kWh of gas every day?

The minimum usage charge is just a ‘fine’ of about 83p per day for periods when you are not using that much (but it doesn’t say what ‘period’ they take the average usage over to work that out).

thanks sparky - their website says :- "Your account is subject to a charge for minimum consumption of 1,678 kWh per year which is applicable on a pro rata basis if average daily consumption in that period is less than 4.6 kWh per day."

I noticed that, it’s confusing wording.  It all depends what this period is that they use for the average.

It can’t be a year, because they wouldn’t need to pro rata if it was.

I don’t think it’s a day, because otherwise they wouldn’t need an average.

So perhaps it’s a quarter, and they will add about £75 to any quarterly bill that is for less than about 420kWh.

skycatcher

Just following this up. Today they have removed the minimum charge in recognition that everyone is trying to reduce their usage so shouldn't be penalised for it. In actual fact it was the volume of complaints to our regulator that forced the change.
I now need to check if it's still cheaper to go prepaid.