[RE-wrenches] Volcanos, reduced solar production and kWh performance warranties

[Dave Click]

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
> ray at solarray.com <mailto:ray at solarray.com>
> 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,
>> marco at pvthawaii.com <mailto:marco at pvthawaii.com> 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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