Anyone know where I might find an honest ROI analysis of solar power?
Everything I find is baloney-nosed in favor of the writer's point of view.
I suspect that solar, if you take away subsidies and tax credits, is a big-time total loser. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
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| 1962 | I love to cook with wine. Sometimes I even put it in the food.
The efficiency of a complete grid tie system is about 75 - 77%. If that is not mentioned then yes, it's baloney-nosed. The price of panels have come down. Used to be $3/W, now you can find
Were it really a cheap form of R&D stimulus. It seems to me that every government-insured loan that Obama handed out for renewable energy (or green anything for that matter) has gone into default... with government guaranteed benefits for his fat-cat buddies who contributed to his campaign. ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Tom Biasi wrote in news:_aMgw.1509943 $ snipped-for-privacy@fx21.iad:
Do the maths yourself. Its the only way to be sure that noone with their own axe to grind has shaded the figures in their favoured direction.
You cannot count on any government subsidised feed-in tarrif or tax rebate being valid past the next budget.
Solar cell lifespan is often nowhere near as good as claimed (e.g. in marine applications, 10 years is an *excellent* lifespan with most failures being moisture and corrosion related. If you are in an area with high pollution levels, on the coast, or next to a road that is salted in the winter, your roof may be as hostile an environment as a marine instalation)
Dirt on the panels vastly reduces efficiency - either budget for regular cleaning or seriously oversize the panels.
Dont forget aging and depreciation for ancillary equipment e.g. charge controllers, inverters etc. Getting lifespan estimates may be difficult
- use a reasonable fixed multiple of the manufacturer's warrenty period if you have to!
Then there's battery banks. Just about every technology except NiFe cells wear out in cyclic use.
Finally, dont forget the lost R.O.I. cost of all the money you would have tied up in the system.
The last time I even ran a back of an envelope analysis (about 5 years ago) it just didn't make sense except for off-grid applications or where the cost of a grid connection would be excessive (either one-off to get the supply cable to the location or recurring costs where the total annual usage is small enough that the standing charges dominate).
I suspect (but cannot prove) that if you figure in the total energy cost of production from raw materials + transport, most consumer lever alternative energy sources are actually a net energy loss over their actual lifespan. Exceptions: wind or water driven generators built using mostly recycled materials and solar thermal water heating.
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Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
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There is one data point to consider. Back in the wake of the oil crisis in the 1970s, a bunch of subsidized solar companies and efforts were started. All vanished when the subsidy ended.
I know nothing of US party politics - other places in the world subsidise solar PV too. It is also a fact that 'fat-cat buddies' will profit wherever they can, whatever the perceived colour.
I also suspect that the panels, batteries, and the associated structures and electronics, will generally not last the 20-25 or whatever years used for the ROI calculations. Nor do they include the roof maintenance complications or cleaning cost.
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John Larkin Highland Technology, Inc
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[speaking from the desert southwest where solar is probably more effective than someplace "up north"]
Solar *pool* heating has an almost immediate payback. Some techniques can payback in one season!
Solar *heating* (passive) has a (relatively) short term payback. Good windows, thermal storage elements, etc. But, if you've got an existing edifice and it's not sited optimally...
Solar *water* is close to 5 years -- if you can do your own plumbing.
[labor costs make many of these things impractical; without the labor costs, many more paybacks make sense!]
Solar PV's, IMO, don't have a payback even with subsidies/credits. We see LOTS of LARGE installations, here and shake our heads in disbelief -- even if they're "youngsters" who've got enough (projected) years on the planet for "payoff" to have some chance!
(How often do you have to work on your roof? even concrete tiles experience failures in the underlayment. Is the roofing contractor competent to remove the necessary panels, repair the roof and replace them?)
Starting over (i.e., if I was younger), I'd first invest in an earth-bermed/below grade living quarters. That alone would make the most savings on heating AND cooling (how much of your electric goes into that big AC compressor(s) out back?)
And, I'd opt for low voltage lighting throughout the house (instead of losing power in converters, etc).
There's a house here in AZ (IIRC built by a dentist) that's totally underground and has flat-screen TV's for "windows" ;-)
Phenomenally low energy costs. ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Yes, the general opinion is solar hot water has the fastest pay back. But with a drawback that the systems are more complex and most likey to be neglected.
There is also geo-thermal heating and cooling, lots here on LI. The pumps use electricity, but the savings on fuel out weigh that.
No. Everyone lies, but that's ok because nobody listens.
As one of those writers (content providers), I'm quite impartial and will weigh the bribes and incentives provided by all sides of an issue with impartiality. What do you offer for me to support your position?
Well, if you're confused by factoids and figurines, I suggest you look at just the big numbers. The little ones will of course have an effect, but it's the numbers with lots of digits after the dollar sign that have the biggest impact on financial viability. To favor your speculation, I'll make some simplifying assumptions.
Everything purchased at retail prices.
5 hrs/day average solar insolation for your area.
No subsidies, tax credits, taxes, time-of-use, or kickbacks.
Net metering payback at about 3 cents/kw-hr.
Cost of installation at ,000 no matter how big the system.
Average cost of utility electricity at 15 cents/kw-hr (3 years out of date).
Grid tied system using microinverters.
Your roof is conveniently pointing due south.
Average annual consumption of 10,800 kw-hrs/year for a three bedroom house.
Ok, now for the guesswork. A fair size system should be about 10Kw maximum output. Solarworld 270 watt panels are selling for about $300/ea. Matching Enphase micro-inverters cost about $130/ea. The central controller is about $1,800. Therefore, the up front costs would be: 40 panels at $300/ea $12,000 Install $8,000 40 microinverters $5,200 Frames and mounts $4,000 Drivel and Trivia $3,000 ========================================= Total $32,200
Assuming a conversion efficiency of about 80% (including all losses),
That will reduce the consumption part of the electric bill by: 10,800 kw-hr/year * $0.15/kw-hr = $1,600/year The $0.03 credit from the electric utility for selling them surplus power will be at: Power produced - Power consumed = Power sold 15,800 kw-hr/year - 10,800 kw-hr/year = 5,000 kw-hr which is worth: 5,000 kw-hr * $0.03 = $150 Therefore, the value of the electricity produced is: $1,600 + $150 = $1,750/year
Break even is: $32,200 / $1,750/year = 18.4 years.
Not great, but still better than the 25-30 year life of the array. The incentives, credits, and deductions that you insist on ignoring will reduce the break even point a few years.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Most installation are grid tied systems, which don't use batteries. For battery type systems, the lifetime varies but seems to settle at about 5-10 years for "typical" installations. Much depends on maintenance (equalization, terminal cleaning, adding DI water, etc) and the local environment (sand storms, falling branches, vibration, etc).
Most current panels will last 40 years, with a guarantee that they'll put out 80% of rated power at 20 years.
Finding repair and replacement parts after 20 years may be a serious problem.
There are non-penetrating roof mount systems that reduce the problem. They're more appropriate for the flat roofs found on industrial buildings, but can be used on some shed roofs. Maintenance of anything that's expected to last nearly forever is going to be a problem. With the dramatic rise in solar power installations, long term issues are probably not an immediate concern, but will need to be addressed eventually.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Actually, solar *pool* heating is a sure-fire choice. But, that assumes you *want* to heat the pool that much (I've been in passively heated pools where it felt like BATH water!)
The cleverest scheme I've seen uses the thermal mass of the pool water to cool the "exhaust gas" from a whole house air conditioner (and, in the process, heat the pool water). Aside from a bit of pipe (which can be PVC) and the actual heat exchanger, no real moving parts (a valve), maintenance, etc.
Of course, assumes your keen on taking on the cost/maintenance of a *pool*...
[We've thought of going this route with an "infinite pool"... though not sure we even want *that* much maintenance!]
It looks this this thread has degenerated into the usual line of crap this newsgroup is so good at producing.
I was going to suggest that a relatively easy way to tell is to get a quote on a specific system, estimate how much power you would get from it in your area and factor in the *real* cost of electricity, reduction in what you buy, vs what the power company will pay you for your excess (if they do).
In Maryland the utility is required to pay you "full price" for your electricity. But now that they deregulated the price only includes generation and not distribution or transmission. I think they are getting some "free" money since that is electricity they don't have to pay transmission costs to get and I expect that is not factored into how they bill transmission costs. However, that is likely not much of a factor to the general public as yet, but it is to the few who sell power back to the utility company.
So is this something you are thinking about doing or just looking for a topic for getting the group wound up about?
- You're using a lot of power during peak day hours and the power company has put you on a variable rate.
- You're facing a choice between adding solar panels or adding power lines.
These are why you'll see data centers and remote hotels with solar panels and other "green" tech. They're running air conditioning and they're near the limit of how much cheap power they can buy. They're becoming popular with highways too - illuminated signs, emergency call boxes, traffic control, low power comms, etc. The cost of stringing wires out to a few remote boxes makes solar panels and batteries seem cheap.
I checked out solar for where I am and it would likely come to a loss. Maybe that will change if a few more neighbors with gas guzzlers buy tiny electric cars for commuting to work.
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