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re: pv's cheaper than ever...
16 may 1999
gigg a watt wrote:
>on my bill... this month... i conserved electricity so much that it only
>costs me $15.84 for the 232 kwh hours that i used... by acting frugally,
>i have brought down my electric bill from about $200 a month to under
>$20 a month...
most people can eaily halve their electric bills, but this is remarkable :-)
then again, your average american won't go vegetarian, eat fresh sprouts
vs refrigerated vegetables, and so on.
>during the winter, when i have to use the central heat
>blower motor, it would be a higher cost.....
solar heating might be next. how many kwh of space and water heating
does your house need, vs electrical energy? that ratio's 1:1 for an
average hawaiian house, 5:1 in vermont.
>so i read my electric bill closely to understand it better, and found out
>that if i keep my electrical costs under 250 kwh... (250,000 watts per
>month)
that's watt-hours per month. talking about watts per month is like
talking about miles per hour per month.
>then i will only be charged at the rate of 2 1/4 cents per 1000 watts...
that's 2 1/4 cents per 1000 watt-hours or kwh. we pay for quantities of
electrical energy, vs rates of use or generation (power.) it makes sense
to talk about a price per (peak) watt for pvs...
>...what appears to be a low rate of 2 1/4 cents (for under 250 kwh of
>usage) actually amounts to 6.8 cents per 1000 watts...
per kwh...
>if 20 watts of pv's cost me about $80...or $4 per watt... (two 10 watt
>panels that are selling for $80)...and the pv can supply 20 watts of
>electricity for 4 hours a day, 7 days a week, 52 weeks a year, for about
>20 years.... then this 20 watt pv panel will produce a total of 582,400
>watts of electricity,
wrong. would you say the distance to pittsburgh is 300 miles per hour?
>or 582.4 kwh over its lifetime...
right.
>now... if we divide the $80 pv costs by the 582.4 kwh... then the pv is
>acutally costing me about 13.7 cents per 1000 watts...
if true, on a continuous basis, that would be a wonderful bargain, vs
$4 per peak watt. even better, with money at an interest rate of 0.0%.
>and that figure doesn't factor in the cost of some new storage batteries
>from time to time...
another 9 cents per kwh for $85 trojan t105 220 ah 6 volt batteries with
1200 cycles at 60% discharge, assuming $0 for shipping and an interest rate
of 0%, or 17 cents/kwh for $198 l-16 350 ah 6 volt 126 pound batteries with
900 cycles at 60%. aee says these are the optimum discharge depths. less
depth increases lifetimes, but requires more batteries, which wear out over
time and increase the time value of money, even with no discharges. there's
no free lunch.
>reading these figures on their face, you might conclude that it would be
>better to use the monopoly utilities, power, rather than use pv's...
another choice: grid-connected pvs, like only shooting yourself in one foot
before the race, economically-speaking. our peco utility pays 22 cents/kwh
for pv energy supplied at peak times (in exchange for being able to charge
ratepayers for $6.3 billion in stranded costs.) fewer batteries needed...
>there are other things to consider... pv's allow a person to place his
>home almost anywhere...
nice... then again, so does a 90 pound $900 honda 1500 watt gasoline
generator, with 7.5 kw of "waste heat" for a house and hot water.
>and if an electical storm comes along... some people lost most all
>of their refrigerated foods...
try comparing the cost of a pv system with installation brackets, labor,
wiring, batteries and inverter with the cost of freezer space for a few
extra frozen milk jugs full of water...
>.....and consider this... there are two, inescapable facts, that you can
>always count on... the first fact being that utility rates will continue
>to rise...
have you noticed that the price per kwh has fallen under deregulation?
>then... there is the second inescapable fact... is that the cost of making
>pv's is coming down... not only are pv's getting cheaper to buy... but
>there are new, more efficient types of pv's, now being developed and
>tested...
every few years since about 1930 we've seen press releases announcing amazing
new technological breakthroughs that will make pvs inexpensive, "real soon."
>...today, we can buy from the eg (http://www.goldmine-elec.com) pv's
>that will cost about $4 per watt... or 13.7 cents per1000 watts over the
>life of the pv.... but... when the lowering costs of pv's reach the magic
>number of $2 per watt...or 6.8 cents per 1000 watts...
oops. your ignorance is showing again.
nick
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