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?
I'm sure you have already looked into this but does adding solar panels increase your property values? I would ask a real estate agent and get their opinion as well. Not that you are looking to sell now (unless you are planning to move to Denver ;-) ) but something else to consider. Have you talked to anyone else who has solar panels? I like the idea of them but have always wondered about the day-to-day upkeep.
ReplyDeleteThat's already included. See the last table above. It has ~$5300 for appreciation of property value. That increases the ROI and IRR. Of course...you don't get that unless you sell...so I don't count that in my calculations.
ReplyDeleteTom, my guess is that the property appreciation is a little on the low side, but that might be because 2kW is a fairly small system. There was a study done in California recently that determined the average house with PV gains $17,000 in resale value, which I've got to think means that you basically get the cost of your panels back. I suspect that, aside from the "revenue" stream of PV, having panels signals to the market that you've taken care of and thought about your house, and people will pay a premium for that. You should also look into Duke's rebate program. I know that Excel out here has a decreasing block rate. For the first 5 MW installed, they rebated at $2/Watt, but for the next 5MW, it's only $1/Watt, and so on. (If I was the first guy in the second 5MW block, I'd be ticked.) Finally, there's a huge social benefit to PV. I haven't read the study myself, but a paper put the actual cost of coal-fired electricity at about 18 cents/kWhr, when you include all the externalities. Obviously, you won't realize those benefits yourself, but on behalf of society, I thank you in advance.
ReplyDeleteBrian, don't forget Tom lives in NC. I suspect the average home buyer there would be afraid of the social stigma of solar. Don't forget conservatives want drilling in Anwr not weeny solar panels! ;-)
ReplyDeleteI want to try this app for CO. If we didn't live in a high rise I bet it would be off the charts out here?
The solar rating of your area is Great for adopting a solar system. (5.51 kWh/m^2 per day).
ReplyDeleteSurprised it's not higher than NC. Definitely more days of sun? Confusing.
5.51 kWh/m2/day in CO is higher than NC. We only get 4.9-5.1 kWh/m2/day. Also y'all get more sunshine (~300 days vs ~220 days).
ReplyDeleteThanks Brian. If you see above, there is a money from Duke Energy...but it's piddly (Dook is fairly stingy) The NC Greenpower is another source which helps more. It's better than nothing, right?
ReplyDeleteIf anything I'd say the solar 'home appreciation' is probably conservative...and I'd rather be on the conservative side. If I was going to go this route, it would be interesting to see what the Homeowners Association thinks. If I have to keep the panels "out of sight", then it's not worth it because my best south facing roof also gets a view from the Street.
I was only half joking about the levels of acceptance for solar by region. Certainly here in CO or in CA it's a big plus. I don't know if acceptance is as high in NC. How do you find out? Ask some Realtor?
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