Grid-tied solar

[farmeratheart]

Yeah- with the snow that we have gotten down here just south of the Mason-Dixon line, we have had several days of 0 or almost 0 kWh ...

 

[dave1949]

The January, 2014 results.

Below the model this month by one good sunny day, or two so-so days. Way below last January too. Lots of gloomy/rainy/snowy weather the first three weeks of January.

Last year, the total system output exceeded the annual model prediction by 12%, or 540 AC kWh.

Month--NREL Model (AC kWh)-----2012 Actual-----2013 Actual-----2104 Actual

Jan.----388----------------------NA--------------440-------------360
Feb.----412----------------------NA--------------375
Mar.----509----------------------NA--------------462
Apr.----374----------------------NA--------------487
May----353----------------------NA--------------375
Jun.----308----------------------NA--------------379
Jul.-----341----------------------NA--------------377
Aug.----383----------------------461-------------470
Sep.----394----------------------481-------------476
Oct.----369----------------------378-------------453
Nov.----283----------------------400-------------414
Dec.----331----------------------297-------------278

 

[dave1949]

Now that I have some history, I can revisit the system payback calculations. My installation included replacing propane-fueled domestic hot water with electric which made it difficult to guess how much propane I use for cooking and how much for DHW, and how much the electric water heater would increase our usage.

Now I can see that cooking accounts for 70 of the 315 gallons of propane we used each year leaving 245 gal. for DHW. The cheapest I have ever bought propane here was $3.05/gal., I will use $3/gal as a cost. 245 gal X $3 = $735 per year in saved propane costs.

The system produced 88% of our total 5664 kWh annual electric usage. Our rate is $0.14/kWh. (5664 X .14) X .88 = $698 per year in saved electric costs.

The total annual savings, propane + electric = $1,433.

The total cost for the installed solar system and electric water heater was $19,774.
19,774 / 1,433 = 13.8 years.

The state rebate and federal renewable energy credits totaled $7,932, or $11,842 net system cost after rebates and credits.
11,842 / 1,433 = 8.26 years.

Certainly, the cost of foregone interest or earnings on the system cost need to be considered, as does the rising cost of electric service and perhaps propane. Propane is never cheap here, I have paid as much as $3.60/gal. in normal times--which is a "shortage" price for folks in the Midwest.

 

[farmeratheart]

Thought you might like to see how the 3+ years of our system performance look ...

Monthly Solar Output of 4kW Array


Month/Year 2010-11 2011-12 2012-13 2013-14
October 538 250 361 424
November 414 380 349 388
December 313 319 242 246
January 268 411 328 270
February 421 429 336
March 563 525 446
April 440 585 582
May 511 518 558
June 580 576 520
July 620 541 510
August 518 552 497
September 518 511 576
Yearly Total(kWh)5704 5597 5305 1328

Here's to hoping for a sunny year!

 

[dave1949]

The February, 2014 results.

Above the model this month by one-two sunny days. Well above last February. It's good to see a sunny month after Dec. and Jan.

Month--NREL Model (AC kWh)-----2012 Actual-----2013 Actual-----2104 Actual

Jan.----388----------------------NA--------------440-------------360
Feb.----412----------------------NA--------------375-------------446
Mar.----509----------------------NA--------------462
Apr.----374----------------------NA--------------487
May----353----------------------NA--------------375
Jun.----308----------------------NA--------------379
Jul.-----341----------------------NA--------------377
Aug.----383----------------------461-------------470
Sep.----394----------------------481-------------476
Oct.----369----------------------378-------------453
Nov.----283----------------------400-------------414
Dec.----331----------------------297-------------278

 

[MtHam]

You mean when they de-regulated it and let the company's set the price etc?

No, California state government under Grey Davis decided that to 'protect' California from market price swings of wholesale power they would lock us in to long term contracts that proved to be disastrously over priced. Another example of how big government is inept! How's your government mandated health care working out?

 

[houstonscott]

When the companies have set prices costs went down. When government gets involved prices go up. Yeah you were taught in California schools that the monopoly's were bad, but Standard oil lowered price of fuel from $4.00 to .35 cents, an inconvenient truth left out of your history books. HS

 

[Loren49]

When the companies have set prices costs went down. When government gets involved prices go up. Yeah you were taught in California schools that the monopoly's were bad, but Standard oil lowered price of fuel from $4.00 to .35 cents, an inconvenient truth left out of your history books. HS

Do you have any references to support this claim?

Loren

 

[houstonscott]

Do you have any references to support this claim? Loren

http://www.fee.org/the_freeman/detail/john-d-rockefeller-and-the-oil-industry
Unfettered free markets are a great thing, built the country and the world. Everyone won. HS

 

[BobRip]

John D. Rockefeller and the Oil Industry : The Freeman : Foundation for Economic Education
Unfettered free markets are a great thing, built the country and the world. Everyone won. HS

Good article. It looks like Rockefeller did best when I faced competition such as the Russian oil. He did not always have a monolopy.