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

[Marco Mangelsdorf]

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, 
ma...@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

 

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10 
20:31:00

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

[Marco Mangelsdorf]

Bill,

 

If, a big IF, I were to agree to a performance warranty, I would want to agree 
to an annual production figure 90 or less percent of the estimated output along 
with a bunch of caveats, like the one you suggest, to render any performance 
warranty relatively toothless.  Otherwise, I see it as way too big of a 
liability and a really bad precedent.

 

marco

 

Hi Marco,

 

I hope this query does not divert response to your original question.

 

How is the situation of the reduced performance due to the volcano (or other 
"acts of God" or the like) approached in the Power Purchase contract? Perhaps 
this could be titled "Reduced Solar Production As a Result of Reduced Solar 
Input". 

 

TIA,

 

Bill Loesch
Solar 1 - Saint Louis Solar

PS As I remember, the last time I bought a new vehicle, back in the Dark Ages, 
the auto manufacturer's warranty deferred to the tire maker's warranty (for 
tires), etc. Any similarity?

 

 

- Original Message - 

From: Marco Mangelsdorf <mailto:ma...@pvthawaii.com>  

To: 'RE-wrenches' <mailto:re-wrenches@lists.re-wrenches.org>  

Sent: Sunday, April 25, 2010 10:02 PM

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

 

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, 
ma...@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

 

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10 
20:31:00

  _  

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

[Bill Loesch]

Hi Marco,

I hope this query does not divert response to your original question.

How is the situation of the reduced performance due to the volcano (or other 
"acts of God" or the like) approached in the Power Purchase contract? Perhaps 
this could be titled "Reduced Solar Production As a Result of Reduced Solar 
Input". 

TIA,

Bill Loesch
Solar 1 - Saint Louis Solar

PS As I remember, the last time I bought a new vehicle, back in the Dark Ages, 
the auto manufacturer's warranty deferred to the tire maker's warranty (for 
tires), etc. Any similarity?


  - Original Message - 
  From: Marco Mangelsdorf 
  To: 'RE-wrenches' 
  Sent: Sunday, April 25, 2010 10:02 PM
  Subject: [RE-wrenches] Volcanos,reduced solar production and kWh performance 
warranties


  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, 
ma...@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

 

  No virus found in this incoming message.
  Checked by AVG - www.avg.com
  Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10 
20:31:00



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

[Exeltech]

Consider adding a "Force Majeure" clause to your contract to cover "Acts of 
God" and other aspects not under your control.

On the other hand, auto manufacturers evade this issue with "Your mileage may 
vary."


Dan





--- On Mon, 4/26/10, Bill Loesch  wrote:
From: Bill Loesch 
Subject: Re: [RE-wrenches] Volcanos, reduced solar production and kWh 
performance warranties
To: "RE-wrenches" 
Date: Monday, April 26, 2010, 6:39 AM


Hi Marco,

I hope this query does not divert response to your 
original question.

How is the situation of the reduced performance due 
to the volcano (or other "acts of God" or the like)
approached in the Power Purchase contract? Perhaps
this could be titled "Reduced Solar Production 
As a Result of Reduced Solar Input". 

TIA,

Bill Loesch
Solar 1 - Saint Louis Solar

PS As I remember, the last time I bought a new vehicle,
back in the Dark Ages, the auto manufacturer's warranty
deferred to the tire maker's warranty (for tires), etc.
Any similarity?
 
 

- Original Message -
From: Marco Mangelsdorf 
To: 'RE-wrenches' 
Sent: Sunday, April 25, 2010 10:02 PM
Subject: [RE-wrenches] Volcanos,reduced 
solar production and kWh performance warranties
  
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 



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

[Max Balchowsky]

We've had a lot of people asking about "performance" warranties and I stay very 
far away from any language that hints at a performance guarantee. I think this 
especially important in the "PPA" I give them all the product specifications, 
run the production charts and then explain how little control I have over the 
things that affect output (to the grid) which includes weather and the way they 
use electricity.

Max Balchowsky
SEE Systems
1048 Irvine Ave. Suite 217
Newport, Beach Ca. 92660
760-403-6810





From: Marco Mangelsdorf 
To: RE-wrenches 
Sent: Sun, April 25, 2010 8:02:58 PM
Subject: [RE-wrenches] Volcanos, reduced solar production and kWh performance 

  
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 PVkWhs 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, 
ma...@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
> 
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10 
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Re: [RE-wrenches] Volcanos, reduced solar production and kWh performance warranties

[Dave Click]

Something you can do is guarantee a kWh amount given a certain amount of 
irradiance. Offer X annual kWh given 2000 sun-hours, perhaps. If you're 
in a snowy area, just make sure the irradiance meter keeps snow on it as 
long as the modules would.


Of course you wouldn't just take 0.8 into PVWatts and make that your 
guarantee... a hot year could impact your production quite a bit so be 
sure to include a cushion. Other things can still bite you here, like 
the aforementioned example where there's a delay getting an inverter 
tech to a remote area.


 Original Message 
Subject: Re: [RE-wrenches] Volcanos, reduced solar production and kWh 
performance warranties

From: Max Balchowsky 
To: RE-wrenches 
Date: 2010/4/26 09:27


We've had a lot of people asking about "performance" warranties and I
stay very far away from any language that hints at a performance
guarantee. I think this especially important in the "PPA" I give them
all the product specifications, run the production charts and then
explain how little control I have over the things that affect output (to
the grid) which includes weather and the way they use electricity.

Max Balchowsky
SEE Systems
1048 Irvine Ave. Suite 217
Newport, Beach Ca. 92660
760-403-6810


*From:* Marco Mangelsdorf 
*To:* RE-wrenches 
*Sent:* Sun, April 25, 2010 8:02:58 PM
*Subject:* [RE-wrenches] Volcanos, reduced solar production and kWh
performance

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,
ma...@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

No virus found in this incoming message.
Checked by AVG - www.avg.com <http://www.avg.com>
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10
20:31:00



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

[Dan Fink]

If you think providing a PV energy output warranty is scary, imagine 
trying to provide one for a small wind turbine!


Fortunately, the Small Wind Certification Council will be giving us 
wrenches a big boost over the next few years as their turbine 
certification program moves forward.


At least turbines will be certified that they perform up to their 
claims, and poor siting issues will become more apparent.


And when your customer demands a small rooftop VAWT in lieu of half your 
planned PV array, you can ask "is that turbine certified?"


DAN FINK
Buckville Energy Consulting LLC



Marco Mangelsdorf wrote:

Bill,

 

If, a big*/ IF/*, I were to agree to a performance warranty, I would 
want to agree to an annual production figure 90 or less percent of the 
estimated output along with a bunch of caveats, like the one you 
suggest, to render any performance warranty relatively toothless.  
Otherwise, I see it as way too big of a liability and a really bad 
precedent.


 


marco



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

[R Ray Walters]

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
r...@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, 
> ma...@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
>  
> 
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10 
> 20:31:00
> 
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Re: [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
r...@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,
ma...@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

No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date:
04/24/10 20:31:00

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

[Jeff Yago]

I would never contract for a guarantee minimum performance for a very simple reason - weather!
 
I think the only reasonable guarantee is to state the "nameplate" output of the array provided under test conditions, and make it clear that  air temperature, clearness factor, dust, cloud cover, and out of tolerance utility grid events will all reduce system performance from this perfect lab value.  Since you cannot control any of these affects on system performance, there has to be a reasonable expectation of system performance for you and your client. 
 
Why do doctors and hospitals have you sign a disclaimer before they render service?  How about accountants, mechanics, engineers, stock brokers, and dentists,   Yes, you can sue for gross negelence, but how many will sign a statement that guarantees their work will have a specific outcome.  Odds are, the small print in the document you sign will point out that there are too many unknowns beyond their control that could reduce the hoped for outcome and if you want a guarantee, -  buy life insurance - you die - they pay -guaranteed.
 
Jeff Yago
 
  Netscape.  Just the Net You Need.
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Re: [RE-wrenches] Volcanos, reduced solar production and kWh performance warranties

[Jeff Yago]

I would never contract for a guarantee minimum performance for a very simple reason - weather!
 
I think the only reasonable guarantee is to state the "nameplate" output of the array provided under test conditions, and make it clear that  air temperature, clearness factor, dust, cloud cover, and out of tolerance utility grid events will all reduce system performance from this perfect lab value.  Since you cannot control any of these affects on system performance, there has to be a reasonable expectation of system performance for you and your client. 
 
Why do doctors and hospitals have you sign a disclaimer before they render service?  How about accountants, mechanics, engineers, stock brokers, and dentists,   Yes, you can sue for gross negelence, but how many will sign a statement that guarantees their work will have a specific outcome.  Odds are, the small print in the document you sign will point out that there are too many unknowns beyond their control that could reduce the hoped for outcome and if you want a guarantee, -  buy life insurance - you die - they pay -guaranteed.
 
Jeff Yago
 
  Netscape.  Just the Net You Need.
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