OK...so this afternoon I met up with Greenspring Energy to discuss the idea of putting up solar panels on the roof. I don't have much area...about 215 sf, by my estimate...so the system would not be large.
Anyhow, so this is the system sizing they came up with:
DC size: 2 kW
AC/DC de-rating factor: 0.93
AC rating: 1.9 kW
Type of Panel: Sunpower E20/327 panels
(E20 = 20.1% efficiency; 327W)
# of Panels (@~61.5" x 21.2"): 6
Expected annual output: 3194 kWh (based on PVwatts with an annual average solar rating of 5.07 kWh/m2/day).
Expected annual energy value: $329 assuming 0.103/kWh
Estimated Price: $12,262
Subtotal minus 30% federal and 35% state tax credits: $4,293
Estimated ROI without any increase in dook Energy rates: 13 years
Estimated ROI with a 5%/yr increase in dook Energy rates: 10.5 years
If I do the buy-all sell-all option, the ROI ends up being the same even at the higher $0.15/kWh due to the increase dook Energy monthly "facilities charge" of $16 vs the current $9/month. Leave it to dook energy to spoil all the fun. So, net metering would probably be the best option.
The system would produce roughly 28% of my annual power usage:
Feb 2011 - Feb 2012: 11,470 kWh or 947 kWh/month
Solar PV as % of Household usage: 3194/11470 = 27.8%
On some months the PV would account to roughly 54% of my usage (May-June) while during January it would only be 17% of my bill.
Overall...I'm not too thrilled about their ROI. Having an ROI of 10-13 years is too high. Plus, I know I won't get my state tax credits until at least 2014 because the State still owes me the second half of my geothermal tax credit.
What's interesting is that when I use the solar-estimator.org site, I get a 6 yr ROI. I notice that the solar calculator includes the Duke Energy RECs ($82/yr) and the NC Greenpower incentive ($264/yr)....both of which are not included in Greenspring Energy's calculations. The solar estimator also only has a 3.78% dook energy annaul inflation rate vs their 5%. The ROI goes to 7 years if I set the inflation rate to zero and then set the electricity rate to 0.0929/kWh. While it's not 1-2 years (like my latest mortgage Refinance)...6-7 years is still a pretty good ROI.
So...what do y'all think? My gut says I should at least wait until Fall 2013 for the tax credits...that's assuming the tax credits survive the upcoming election...to minimize the amount of time I have to wait for the tax credit return.
Also...solar technology is evolving quickly. New multi-junction concentrated solar panels are achieving 30-40% efficiencies: http://cleantechnica.com/2011/02/17/high-efficiency-solar-cells-getting-more-efficient-cheaper/
Who knows...in a year these bad-boys could be selling thus allowing me to get even more power from my small roof area (yes...most likely at a premium price...but if the ROI is right...)
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