Actually....was...Re: Solar Ideas - long but hopefully informative

[JoE McCabe <energyi@mccabe.net>]

Dear SB'ers, and my buds down in Souther CA. 

I do these PV numbers for a living, and Skip is just about right on! The
500 systems installed in CA under the buy down program are showing between
$8k and $10k per kW (with exceptional frugality at $6k / kW). 

And, for San Diego, a 1 kW system produces about 2,000 kWh / year. (see
shareware BIPV Designer at www.energyi.mccabe.net). Notice that the 50%
California buydown (http://www.energy.ca.gov/greengrid/) will pay half of
the system, and the present value of the system is $3,000 (8% money, 20
years for $300 / year). Basically, the economics are break even at 20 years
for just the $/kWh's at $0.15/kWh. If you think electric rates are going to
go up, or if you think the game is going to change with "time of day"
rates, then you will be ahead of the game with PV. OR, if you care about
the environment........

However, I am installing a system on my house, souther exposure roof, where
I will be eliminating the direct beam radiation hitting my shingles. Thus
eliminating a significate airconditioning load on my house, reducing my
electric bill. I also have the potential for un-interuptable power with a
small battery bank (another California buy down is happening for batteries,
stay tuned to SB 1345). What is it worth to have power on during black-outs?

The real thing you bale-heads should be thinking in your new SB building is
displacing the cost of the roofing material with PV. Your economics will go
much higher if you were going to have a person on the roof anyway. Use PV
to effect whole building energy usage, provide shade on the south side
(north in souther hemisphere) of the building to reduce heating in summer
months (but alow for winter sun if you want passive solar gains). 

Hope this helps.

JoE
PSsshh: I can also harvest heat energy off the back sides of the PV (but
don't ask) ~smiley~.

At 02:00 AM 1/28/2001 -0500, Bob and Skip wrote:
--
>First, and foremost, your calculations are right on (about 20 year-plus
>paybacks)!  Also, the 6 hours a day peak output is a bit high for San Diego
>and most regions.  I assume about 1800 t0 2000 kWhs a year per peak kw
>installed here.
>Typical PV residential systems here are costing around $8,000 to $10,000 a
>kw, grid-tied, with no batteries.  Rates here have been hanging around $.20
>a
>kwh for several months.  I expect them to drop, but who knows how much?
>California also has a "Net Metering" law that essentially unwinds the
>electric meter whenever PV energy is fed into the grid.  One other incentive
>here is a $3,000 rebate from the utilities for a grid-tied system.  Putting
>all the optimistic numbers together ($8,000 cost, $3,000 rebate, 2,000 kWhs
>a
>year sold at $.20/kwhr, gives a 12 year payback.   If the system cost is
>amortized in a 30-year mortgage at low current rates, the monthly costs
>(interest tax-deductible) can be close to the average utility cost (assuming
>they stay high), and would thence serve as a hedge against future rate
>spikes.
>I don't advise my customers to do PV on grid homes if economics is their
>main
>concern.  As happened when solar water heaters 20 years ago had 15-year
>paybacks against natural gas, and many people still chose to buy, this is
>starting to happen now.  Many people buy for reasons other than short
>paybacks.  Many buy to make a statement, or to contribute to growing a good
>industry.
>The best application of residential PV is for new construction, where a
>power
>line might have to be run for more than a third or half-mile.  Then a
>pv/battery/generator system might be more cost effective, especially if
>sound
>passive, strawbale, efficient appliances, principles are incorporated to
>reduce the size and cost of the PV system.  My company, Sustainable Earth

>Enterprises (www.StrawBaleHouse.com) builds straw bale and other natural
>passively-conditioned homes, and solar thermal & electric systems.  With
>intelligent design, an energy efficient house can be built for about the
>same
>as a house using 2 to 4 times as much energy.
>So the bottom line recommendation is design the home as a system, not to
>just
>look at one component.
>Hope this helps.  Email or call me if you have more questions.  Your
>analysis
>was very good!
>Skip Fralick
>619-985-2603
>solarskip@aol.
>
>Poway, CA
>(San Diego County)
>www.strawbalehouse.com
>
>------------------------------
>



.
Joseph McCabe, P.E.
Energy Ideas
(530)795-2930
energyi@mccabe.net


www.energyi.mccabe.net

New location in Davis/Sacramento area.



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