[RE-wrenches] Sanyo Semi-facial

[Bill Brooks]

Geoff, Daryl, and others,

To be clear, Sanyo's product is not an amorphous-silicon (a-Si) product. It
has a-Si coatings that help with the electron flow at the surface of the
cell. There is no reason to believe that the Staebler-Wronski effect, so
well known over the past 30 years, has any impact on this product. It is not
really a multi-junction cell. 

The issue of sizing inverters to array size is a many-facetted issue. I
conservative rule of thumb would be to size the array STC-rating to be equal
to the ac KW rating of the inverter. As long as you are clear that the
system will only very rarely ever reach full power, everything is fine. It
is less of an art than a science in that programs, such as PVSYST, can
predict quite accurately how much energy is lost if you undersize a PV
inverter. The 125% array-to-inverter power number discussed below would only
hold true for installations that are dominated by hot conditions, modules at
minimum spec of -10% of nameplate rating, and no snow or altitude
enhancements. 

Inverters are so much cheaper now that undersizing inverters makes very
little sense.

Bill.


-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Geoff
Greenfield
Sent: Wednesday, April 15, 2009 6:15 AM
To: daryl solar
Cc: RE-wrenches
Subject: Re: [RE-wrenches] Sanyo Semi-facial

My understanding of amorphous is that there is a 2-3 week burn in of higher
performance, then it levels off. The rated watts reflect the levelized
performance. 

Re overstacking an inverter:  the sma report from their sizing tool is
useful- balancing best value, long term performance and inverter reliability
is an artform more than science. Adding modules that perform at spec when we
are used to a larger derate makes it that much trickier.  

For a brighter energy future,

Geoff Greenfield
President
Third Sun Solar & Wind Power Ltd.
340 West State Street, Unit 25
Athens, OH 45701

740.597.3111     Fax 740.597.1548
www.Third-Sun.com

Clean Energy - Expertly Installed






----- Darryl Thayer <daryl_solar at yahoo.com> wrote:
> 
> hi all
> 1) I have a 97kW system that just hit 95kW peak, which surprised me.  
> 2) Overloading the inverter, I was told that slight over load is OK and
that if you overload up to 25% you will not have any significant annual
loss.  If this is not correct please up date me.
> DT
> 
>