November Energy Bill

I got the latest Energy bill in yesterday.  Here's the results:

Nov 2011-
Total KWH:  734
Days:  29
Avg KWH/d:  25.30
2010 Avg Kwh/d:  26.28
Savings:  3.67%
Comparing to 2009 townhome:  108.1%

Yup...not a huge savings.  But then recall, the bill is label November, but it's actually for October 4 - November 2nd.  Well...for about half of October, the HVAC system was turned off.  Then we started getting those cold nights (30s-40s) so the heat was turned on.  Those cold temperatures are unusual for this time of the year (did you guys see the October New England snow storm?)

Overall, I think we're fine.  Now NEXT month is going to be exciting.  As a preview, last year we used 1374 kWh for the month or 45.80 kWh/d.  We're averaging 32.2 kWh/d right now...and that will be back to the normal ~30% savings.  After that in January we used 3,224 kWh and in February it was 1,967 kWh....I expect HUGE savings over those months.  Since we've installed the Geothermal system, our largest month was 1086 kWh...

Cost of Going Solar...is it worth it?

Ok...so I've been mulling over additional ways to save money.  If you've been following...that's included changing out the HW heater for one.  I've also been thinking about replacing the siding on my house (which is the old Masonite stuff...which had a lawsuit against it...which expired right after I bought my home)...whch would include Housewrap which should reduce energy bills by 10-15%. 

The other thing, I've been thinking about is solar power.  Adding this in would significantly reduce my bills...but at a significant cost.   So I did some research and came upon a handy website that allowed me to determine the cost of solar.  This saves me a lot of heartache of doing it myself...and it appears to be fairly comprehensive.  The site is:  solar-estimate.org and its a free site that is run by "Energy Matters LLC" which makes web-based tools for marketing and sales in solar, wind, renewable energy, and energy efficiency industries.  So given that this site was probably paid for by a professional organization looking to advance the industry and not one specific business, I feel fairly comfortable using the tool.

So, I input my location, selected my Utility, along with some other minor stuff (residence, I want to review solar PV, etc) and it says I have a solar rating of "GREAT" at 5.09 kWh/m^2/day.  I've seen this value before and when I look at those "solar maps", my area is right around 5, so this makes sense to me. This is the "average solar radiation during an average year".  Next I entered the following information:

From above, nearly all of this stuff was pre-filled in for me.  Note that I said I only wanted to put in a 25% system (2kW)...since if I did do this, I'd want to start off small.  The install cost shown is from a help file that shows its about $9/WDC <2 kW installed and $8/WDC for systems =>2kW.  Note that my utility inflation rate was suggested at 3.78% based on whatever data, solar-estimate.org has.  This actually is probably pretty close.  I've looked this value up numeous times for Engineering reports and, in general, Utility inflation is about 4%.  So I'm comfortable with this.

So after, I put this stuff, in I  got the following for system sizing:

  The energy bill is right on.  When I track my energy bills via Mint.com, I  get roughly the same.  OK...so this says I'd need roughly a 2.25 kW system and I'd need 226 ft2 of roof area.  Note:.  2.25kW is roughly how much energy my geothermal system needs when its running (for half...so either the upstairs or the downstairs).  .How big is 226 ft2?  If I assume a 4-ft long solar panel and I put 2 end-to end, then I'd need an area that's 8-ft x 28-ft.  That's really not all that big. This estimates an annual production of just under 3000 kWh.  Note that there is some hidden math behind here...because this is not just simply:  226 ft2 --> 21m2 x 5.09 kWh/m2/day * 365 days/yr...because this equals 39,000 kWh/yr.  The 226ft2 (or 21m2) is based on 10W/ft2 average solar panel sizing.  So this obviously has some fairly high conservatism in it. I get fairly similar values when I run the Dept of Energy's PV Watts...this gives me a solar rating of 5.07 kWh/m2/day and an energy production of 2976 kWh/yr.  If I use data from an existing PV system (adjacent to the fire station roughly 2.5 miles away, I get 4.91 kWh/m2/day and and equivalent annual production of 2863 kWh.  So this is neighborhood.

Next it gave the rough cost for the system:

$18.1K?  Installed cost?  OK...I can believe that.  I've heard numbers floating around and this makes sense to me.     The next part is really cool...they show me how the incentives work.  I've seen these before since I got the same one's for my geothermal system...for exception of the Duke Energy and NC Greenpower adders:

Overall...this is showing my a rough ROI of 9 years.  That's not overly great...but then again, it's not overly bad either.  Most of my other options (i.e. HW Heater) don't have an ROI for 10+ years.   The information below gets into more detail on the savings. 

Overall...this appears to be a good investment if you take into account the 25-yr net present worth.  So maybe someday, I'll have some extra cash on hand and I'll look into this.  Also...possibly by then...prices of solar panels will have come down helping the ROI.   I definitely like the idea. 

One thing I'm still tentative about is what maintenance needs to occur.  Do I need to go up to my roof every fall and get the leaves off?  Do I need to wash the system (espeically if a bird decides to unload)?  Anything else I need to do?

When and if I install a system....I'm sure I'll blog about it...so you'll know.

Any thoughts out there?

Brrrrr...

Hello all-

It's gotten cold in the Carolina's the past couple weeks.  Morning temperatures have been flirting with the high 30s...with afternoon temperatures in the high 50s, low 60s.  You know what that means....the heat is on.   Below is the TED historical usage.  Electricity usage is up into the 30 kWH/d range.  Those days that show usage in the 40 KWH/d are when we're doing laundry (Sunday/Monday).  It's amazing how much the eletric dryer uses even though we have a high efficiency washer which really spins the water out of the clothes.  Maybe I'll investigate the default settings on the dryer to see if I can save some energy there...but I kind of doubt I'll find anything. 


TED Historical Usage up to 11/2/2011

My HW usage is up too...not suprising as anyone can tell you how nice a hot shower is on a cold AM....even though I have the super-low flow 1.5 gpm showerhead.  And now I have the results to show it (see below).  On average we're using about $0.50-$0.60 per day on HW.  One an avearage month...that's $15 in my Bill.  Probably at best, I can reduce that by about 50% if I upgrade my HW heater to one of those GE Geospring Units and run it in series with my existing HW (turned off) to maximize the geothermal desuperheater.  At that amount ($7.50/mo), I'd save $90/year.  Thus it would take roughly 10 years to pay off the HW heater. That's not exactly a great ROI, but who knows...maybe prices will drop to make it more attractive.  I really wish Duke Energy would offer a rebate on higher efficiency hot water heaters to make it worthwhile.  A $300 rebate would mean 3 years off the ROI, which is great.  But...Duke energy's program is for HVAC only...bah!

TED HW Usage - Oct 31, 2011

FYI...so the NC Utilities commission, denied Duke Energy's request for the 15.4% rate increase this year.  Instead they recommended a ~5% increase.  Duke's pretty pissed about this and I'm sure they'll find another way to get the rates out of us.   Maybe I'll need to start really looking at solar panels soon...