Good call Ray to incorporate out-of-spec grid in areas where that's an
issue (and probably a good idea to include just in case!).
If you need justification on future projects as to why you can't just
guarantee a flat #:
http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/interp.html
"For these variations and the uncertainties associated with the weather
data and the model used to model the PV performance, future months and
years may be encountered where the actual PV performance is less than or
greater than the values shown in the table. *The variations may be as
much as 40% for individual months and up to 20% for individual years.*
Compared to long-term performance over many years, the values in the
table are accurate to within 10% to 12%."
R Ray Walters wrote:
I think to make any energy production warranty fair, it would have to
include an on-site monitoring package that tracked cell temp,
insolation, and grid conditions. Then the installed system would be off
the hook if the grid was out of spec, insolation levels were low, cell
temp too high, etc. The performance warranty would be limited to the
actual site conditions.
I know its scary, but the one advantage I see of this type of warranty
is that it gives an edge to companies that do a better job, better
installation, and sell higher quality equipment.
It definitely would separate the wheat from the chaff. (or the Sunpower
from the Chinese poly)
R. Walters
[email protected] <mailto:[email protected]>
Solar Engineer
On Apr 25, 2010, at 9:02 PM, Marco Mangelsdorf wrote:
This thread brings up a very timely issue that I’m dealing with right
now with PV Power Purchase Providers. As an integrator providing
turnkey PV systems of X kW, I’m being asked to contractually agree to
a minimum performance warranty for said PV systems. I am EXTREMELY
uncomfortable to any such clause in any contract that I would sign. I
have strong confidence in my PV design capabilities and engineering
support and in my professional crew to install a top-quality PV
system. I have a lot less confidence in an inverter manufacturer being
able to get to a site on a Hawaiian island in the middle of the
Pacific in a super timely fashion as the lost PV kWhs rack up. And as
I mentioned in a previous post today, we have an active volcano here
that’s been spewing since 1983, a volcano that could get a lot worse
on any given day. I’m leaning strongly against agreeing to any such
clause. Way too bad a precedent to set. Way too much of a liability.
Anyone else had to deal with this bugger of a performance warranty demand?
Thanks,
marco
ProVision Solar
Marco:
Our production /schedule/ has been in tatters - lowered by perhaps 30%
because of the rain.... can't plan, can't do. Then I pay overtime on
good days to (try to) catch up.
We have a number of systems online and I had not thought to actually
review and compare from this year to last. I'll let ya know.
We'll get a call like - "My bill is higher than last year (edison has
a bar graph of monthly consumption for the past 13 months) and I'd
like you to look at my system" or My meter is not going backwards,
should I call edison?" The weather is so consistently wet this winter
(think Hilo) that we usually just need to ask-
"Been outside lately?"
But everywhere is so green and the desert bloom is outrageous.........
http://www.desertusa.com/wildflo/ca.html
Pat Redgate
Ameco Solar
In a message dated 4/25/2010 12:24:53 P.M. Pacific Daylight Time,
[email protected] <mailto:[email protected]> writes:
Pat,
Kicked your butts as far as lower output? If so, by how much on a
percentage basis?
On the Big Island of Hawaii, we’ve had a very active volcano doing
its thing since 1983. With the normal trade winds, the vog
(volcanic smoke + fog) gets blown south past the volcano, around
the south tip of the island and */then back up/* along the west
side of the island. Which means that Kona-side residents can be in
a yucky vog zone for days and sometimes longer. Think L.A. on a
smoggy summer day. And as far as percentage decrease in solar
output, I really have little accurate clue.
Marco
ProVision Solar
Kicked out butts, in fact.
Pat Redgate
Ameco Solar
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