Grid-tied solar

[whirly]

Not sure how you got your result, but here's the rates by year, starting with year 0 and ending with year 20 (a 21 year window):

100
103.3
106.7089
110.2302937
113.8678934
117.6255339
121.5071765
125.5169133
129.6589715
133.9377175
138.3576622
142.923465
147.6399394
152.5120574
157.5449553
162.7439388
168.1144888
173.6622669
179.3931217
185.3130947
191.4284269

Each year's value is 1.033 times the previous year's value (a 3.3% increase).

The formula is simple:

(1+i)ⁿ where i= rate of increase and n= number of years. Therefore a 3.3% increase over 30 years is:

1.033 to the power of 30 or 2.64855 times the initial rate or 264.855% increase over 30 years.

 

[meburdick]

The formula is simple:

(1+i)ⁿ where i= rate of increase and n= number of years. Therefore a 3.3% increase over 30 years is:

1.033 to the power of 30 or 2.64855 times the initial rate or 264.855% increase over 30 years.

True.

The author of the original number stated 30 years but calculated for 20. For whatever reason, I read it at 20 and calculated for 20. At 30, you're dead-on.

 

[newbury]

Not sure how you got your result, but here's the rates by year, starting with year 0 and ending with year 20 (a 21 year window):

If you were responding to my post, if you had checked my link you wouldn't have had to make such a long post.

Links like Compound Interest Calculator (easily found by searching for compound interest calculator) make life so much simpler when the computer works. Don't even need the slide rule.

 

[meburdick]

If you were responding to my post, if you had checked my link you wouldn't have had to make such a long post.

Links like Compound Interest Calculator (easily found by searching for compound interest calculator) make life so much simpler when the computer works. Don't even need the slide rule.

I did read your post, and I also read the link you supplied. See my previous post and you will see that I was showing the schedule for 20 years (which is what I *thought* you were quoting values for).

 

[Alien]

Perhaps I should have gone into a little more depth. When we fitted our solar we were entitled to a feed in tarrif for any excess power we fed back to the grid. This does help offset the high cost we pay for energy. (locked in for the next 16 years.) I wish I could have afforded a larger system than 4 Kwh but we are happy with what we managed. The tarrif is 44c subsidised by the Govt and the Energy company adds an additional 6 cents. We normally had a power bill close to $500 per quarter but our last bill (and first) under the tarrif system left us $4.78 cents in credit.
To us it was a no brainer to install solar due to our circumstances but everyone has different criteria and I find it pointless to argue the pros and cons when there are so many variables.

 

[RobertN]

We have been bumping 32KWh for the last three months. Our 5KW system, has us hitting net zero for the year. We're an all electric house, but do a lot of heating in the winter, with a wood stove.

I have seen hinted, that many are comparing just todays electricity rates for the payback. Electricity rates keep rising, so the payback times shortens.

 

[meburdick]

I have seen hinted, that many are comparing just todays electricity rates for the payback. Electricity rates keep rising, so the payback times shortens.

Very true. But cost increases are not always guaranteed to happen in any given year / quarter / month, nor are the amounts set in stone. Using "today's rate" gives you a known constant to work with, and it's better than nothing.

If deregulation *really* kicks in, or if the generation companies start using more efficient means of producing, we could actually see some reductions in costs from time to time. Going based on today's cost gives you a starting point that should seemingly be "worst case". Think of it this way... When you buy a car, and the label on the window shows a mileage rating for city and highway, do you base you estimated fuel usage solely on the highway mileage? That would be assuming "best case", and it isn't likely. If you base your usage on city driving, that's "worst case" and it can only get better. It's the mantra of "Plan for the worst, hope for the best."

 

[JCByrd24]

Well if I had $.05/kwh rates my thought process would be different too, especially consuming at the rates you are. I'd probably build the same house and be doing swell with a sub $50 average monthly electric bill (including heat) instead of coughing up $15K on a PV system. It amazes me that power is that cheap anywhere, especially CT. The amount of power you consume would cost me $245/month here.

I wouldn't exactly consider Maine a mild place to live though, little cooling costs but lots of heating to do from Nov through April, even compared to CT.

 

[RobertN]

Yes, we took all of that in to consideration before getting our solar hot water, and then solar electric. Don't count your chickens before the eggs hatch...

We're in sunny Kalifornia. I really do not see prices for electricity going down out here. Stable maybe on a lucky day. Up, yes.

Very true. But cost increases are not always guaranteed to happen in any given year / quarter / month, nor are the amounts set in stone. Using "today's rate" gives you a known constant to work with, and it's better than nothing.

If deregulation *really* kicks in, or if the generation companies start using more efficient means of producing, we could actually see some reductions in costs from time to time. Going based on today's cost gives you a starting point that should seemingly be "worst case". Think of it this way... When you buy a car, and the label on the window shows a mileage rating for city and highway, do you base you estimated fuel usage solely on the highway mileage? That would be assuming "best case", and it isn't likely. If you base your usage on city driving, that's "worst case" and it can only get better. It's the mantra of "Plan for the worst, hope for the best."

 

[dave1949]

Well if I had $.05/kwh rates my thought process would be different too, especially consuming at the rates you are. I'd probably build the same house and be doing swell with a sub $50 average monthly electric bill (including heat) instead of coughing up $15K on a PV system. It amazes me that power is that cheap anywhere, especially CT. The amount of power you consume would cost me $245/month here.

I wouldn't exactly consider Maine a mild place to live though, little cooling costs but lots of heating to do from Nov through April, even compared to CT.

We put the sun to work for that too. Our house is direct-gain passive solar with full earth berms except the south side. Lots of south windows, lots of insulation, lots of concrete for thermal mass. We have a 3 ton soapstone masonry heater we fire most days, usually in the early evening. We use less than a cord of wood per year. In the gloomy time around the end of December, we turn on electric space heaters overnight in the bedroom if it hasn't been sunny. The bedroom is too far from the stove to benefit much.

It isn't for everybody, the temperature will hit 80 deg. on a clear winter day, we open windows a crack sometimes. Overnight, the temperature bottoms out around 68 degrees typically.