SecondCor521 said:
Never mind. I found books that appear to answer all the questions I had plus more.
No problem, sometimes doing nothing is my best tactic. (Well, OK, our kid was hogging the computer last night with lame homework excuses.) Let me know if your analysis runs into roadblocks-- I used
Keith Cronin's website as one resource and I can point you to HECO's Ron Richmond and a local engineering thesis student named Jeff Mikulina. All nice guys.
SecondCor521 said:
Where do you find cheap panels, though? A quick google found me a 161.5 watt panel for $850. That's new, of course, but it makes the system really expensive. I did a quick calculation and it looks like it would take a 28 panel system to meet my energy needs at 5.4 peak sun hours, 80% battery efficiency (I think I could take that factor out if I did a grid-tie system like you), and 90% inverter efficiency, assuming 16.86 kWh / day usage. That system is $24K just for the panels, which is obviously way too high.
I think unless I find cheaper panels or move to a sunnier area this may be a non-starter.
It's not impossible but it takes a lot of time & patience. We bought old used panels-- parent or even grandparent technology-- and blemished factory seconds. They all have lower power density & conversion efficiency so they "waste" a lot of roof space. You pay a premium for higher densities & efficiencies but a 3KW system can indeed cost close to $30K.
Unfortunately $5.25/watt is a pretty good retail price. Your rough $24K for 4500 watts of panels isn't too far off considering a $3K inverter plus mounts, racks, connectors, & labor. Many modern panel designs cost $6-7/watt retail and up to $9/watt installed.
Keep in mind that we spent a grand total of $14,500 on our current 3 KW system and I haven't yet installed another five panels that cost $1075. We've already racked up $6000 of tax credits over the last three years' returns and we have another $1700 in the buffer. Those subsidies really make the $$ math work.
The mechanics of finding cheap panels comes under the heading of "Whaddya do all day."
My last buy was on eBay. It was his first sale (under that name, anyway) so no one else was bidding. He even paid for Hawaii shipping so my cost came to about $3.36/watt. I ran a daily search for over two months, sorted through hundreds of items each day, swapped dozens of e-mails with sellers, and dropped out whenever the auction bids exceeded $4/watt. The other business retailers who sell panels on eBay generally agreed that I was a cheapskate and refused to discuss less than $5/watt. The best deals come from estate sales, storage auctions, and other one-time sellers who really had no interest in what they were getting rid of.
My next largest purchase was from
Sun Electronics in Miami. They sell heavily on eBay and I bought $7000 of cosmetically-blemished Evergreen 115-watt panels from them. That was a bit of a leap of faith (as well as the $700 shipping fee across five time zones that took a month) but they gave good service and the panels make up most of our array.
SecondCor521 said:
Interesting. What I had read so far this afternoon indicated that a grid-tie system is complicated by the fact that the power company will want to inspect your system and impose requirements on it so it doesn't foul their power system up. I can see how skipping the whole battery part of the system would make it simpler from a design point of view.
Yep. Grid-tie is the most cost-effective design but it involves a lot of people whom you'd rather not deal with. Not only do they want to inspect it, but you'll need a construction permit and a licensed electrician. Keith was extremely patient with me (I kept trying to apply logic to the building & electrical codes) and he did only the electrical work yet I was thrilled to pay him over $400 to run the permit paperwork. Jeff Mikulina told me that out of over one million Oahu HECO customers, we're one of only two dozen homes with grid-tie PV permits. The city's permit staff and HECO's "inspector" had never seen a PV system before (literally!) but they were happy to approve the paperwork that Keith had previously run through HECO and the local legislature. I'm not implying that Keith had bribed anyone-- his contractor's lobbying group went through a tremendous education effort to smooth the bureaucratic approval process. After I'd tried it on my own I would have paid him $800.
A couple months after we'd installed our system, including the permit inspection and HECO's approval of the net-metering contract, a separate branch of HECO sent an inspector out to the house. His job was monitoring their accounts for abrupt changes in customer energy useage-- we'd popped up on their list as either possible energy thieves or missing/dead. He'd also never seen a PV system before and Ron Goodman took a lot of teasing from the contractors about that one.
Google "guerilla solar" for stories of homeowners who just don't want to bother the utilities or the regulating agencies...
SecondCor521 said:
I don't really care about going off grid except for the cool/geeky factor of it. I am interested if I can invest capital up front that provides me with a return that speeds up my FIRE date.
There are three ways to look at it: return of capital, dividend, and opportunity cost.
The fastest payback, most favored by contractor sales staffs, is the return of your capital. It's the cost of the system divided by your monthly savings, and a "typical" ROC is 20 years. Tax credits (and excavating the bottom of the barrel) reduces that to 10-15 years, and rising utility costs (the energy CPI?) may reduce that by a few more years. It's highly variable and location-dependent so you end up doing your own research & calculations.
The second-fastest payback, also popular with sales staffs, is dividends-- especially since you don't have to depend on the stock market or a bunch of company execs. But although the dividend rate may be among the market's highest, paying back a 7% dividend still takes over 14 years.
The most accurate method is opportunity cost. (You'll never hear about this from a sales guy.) I assumed that every penny we spent on a PV system could've been invested in a low-cost index ETF returning 6%/year after taxes. I model this with a rudimentary spreadsheet to track its growth against the growth of our PV savings. Every month I read our KWhr production, check HECO's $/KWHr retail rate, and compound that amount at 6% APY. Even with the tax breaks the two lines don't cross for another 11 years. I didn't measure the energy savings of our solar water heater but I suspect that it's a big part of the overall picture-- yet that's a reduction in consumption.
SecondCor521 said:
Unfortunately for my my south facing roof is the right side of my garage roof, which faces the street. I think my HOA folks would have an issue with solar panels. Maybe not.
Luckily ours faces the sewage booster station at the end of our cul-de-sac and our system is not easily seen from the street. Our HOA had no objections but you're right, it'll probably require their approval. The good news is that they won't want to look like green Luddites and they'll probably approve the panels just to stay out of the media.
CFB has correctly pointed out that no homebuyer will pay for your PV array. I wanted to look at a local guy's system and found that he'd moved to the Mainland, but he gave us the phone number of the new owner. The new guy graciously showed us around but had no idea what the PV components did, where they were located, or how they affected his electric bill. He admitted that if they broke then he wouldn't even bother trying to get it fixed.
The flexible rollout panels fill me with Dilbert engineering consumer lust; they're going into a local military base-housing neighborhood to become the nation's largest residential solar installation.
Ovonic also makes a line of PV roof tiles that looks incredibly cool. In two or three decades our new south roof will probably use those... unless I see them on eBay sooner!
T-Al, I've seen small systems like that at Home Depot. They were advertised as "laptop power supplies" or something similar-- just a panel, a black-box inverter, and a receptacle plug. One of my favorite references for those products is
http://www.backwoodssolar.com/