Yeah, they have "summer" and "winter" rates.

It will probably go down a bit later on.

Also, you do indeed *seem* to be spending more with your example

1000 kwh per month @ 5 cent per month= 50 bucks

900 KWH per month @ 6 cent per month = 54 bucks

However, you're not making a valid comparison. True, you've spent $x to save that 10%, fair enough.

But you have to consider what you'd pay if you didn't spend that $x.

So really you're looking at it this way:

1000kWh @ 5c = $50

1000kWh @ 6c = $60

1000kWh @ 7c = $70

1000kWh @ 8c = $80

now if you spend $x to reduce by 10%:

1000kWh @ 5c = $50

900kWh @ 6c = $54

900kWh @ 7c = $63

900kHw @ 8c = $72

and so on. as the price increases, you're still saving 10% compared to if you did not upgrade to more efficient items.

In the above example, if each tier is a year of usage, you'd have saved:

50(12) + 60 (12) + 70(12) +80(12) = $3120

With your 10% efficiency increase:

50(12) + 54(12) + 63(12) + 72(12) = $2868

You saved $252 in those 4 years by reducing your usage by 10%, even though the price rose 1 cent consecutively for each year.

So then, you have to consider how much an upgrade costs - if you didn't need to replace it and it cost you $4000 to save 250 over 4 years, was it worth it?