[RE-wrenches] [RE Marketing] PV system Performance guarantee

[Hans Frederickson]

Rather than base a performance guarantee on average annual production and
introduce the possibility of disagreements about the weather, power quality
knocking inverter offline, and other things beyond your control, I think
it's better to stick to the manufacturer's performance guarantees and
measure instantaneous production to ensure that the array is performing as
expected for the irradiance and temperature on a given day. If one of my
customers had a concern about production, I would go out on a clear day with
my multimeter, daystar meter, and surface temperature meter. Take the
measurements, plug in figures for inverter efficiency, degradation from
aging, etc. and compare expected AC watts with actual. This doesn't account
for intermittent inverter dropouts that might effect annual production, but
it does show whether the array is performing as expected.

Regards,
-Hans

________________________________

From: re-markets-bounces at lists.re-wrenches.org
[mailto:re-markets-bounces at lists.re-wrenches.org] On Behalf Of Joel Davidson
Sent: Wednesday, August 05, 2009 11:42 AM
To: RE Marketing for home scale RE industry
Subject: Re: [RE Marketing] PV system Performance guarantee


Each company has its own performance contract. In general, if you monitor
the system by internet and it is reasonably close to your shop so you can
fix problems quickly, then you should be able to guarantee kWh/month within
5% of the PVWatts conservative estimate with the condition that daily
weather is within the normal 30-year climate range.

	----- Original Message ----- 
	From: bill roush <mailto:billroush at gmail.com>  
	To: RE Marketing for home scale RE industry
<mailto:re-markets at lists.re-wrenches.org>  
	Sent: Wednesday, August 05, 2009 7:42 AM
	Subject: [RE Marketing] PV system Performance guarantee

	Anything out there on what is reasonable to ask of a contractor for
a  Performance Guarantee on a PV system? 5 years/less? Based on what
parameters?  Same for home, small commercial and larger commercial?

	-- 
	Best,
	Bill Roush
	Heartland Solar Energy Industries Association
	www.hseia.org
	Heartland Renewable Energy Society
	www.heartland-res.org
	

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