Opened 5 years ago

Closed 5 years ago

#935 closed task (fixed)

revised de-rating of PV system performance

Reported by: cchriste Owned by: cchriste
Priority: normal Component: Modeling - General
Version: 0.0 Pending Review Keywords:
Cc:

Description

From Aron Dobos on the latest approach in SAM (10/21/14):

SAM uses some of the older PVWatts derate factors, but some of the biggest changes to Pvwatts were in the inverter model. The original Pvwatts assumed a 92% efficient inverter, which is really outdated. The new PVWatts V5 that was released last month (pvwatts.nrel.gov) updates this and makes several other changes, summarized here: http://pvwatts.nrel.gov/version_5.php

The new PVWatts predicts roughly 7-9% more energy on an annual basis than the old V1 for the default inputs.

The details and validation are in the technical manual: http://www.nrel.gov/docs/fy14osti/62641.pdf

Also, we’ve gone away from derate factors, and switched to loss percentages. This makes SAM and Pvwatts consistent with every other PV modeling tool out there, and is generally easier for users to understand.

Change History (2)

comment:1 Changed 5 years ago by shorowit

  • Owner changed from shorowit to cchriste
  • Priority changed from high to normal
  • Status new deleted
  • Version changed from 2.3.0.0 to 0.0 Pending Review

r4810.

The only thing we didn't address is: "System sizing is explicitly handled by the new DC-to-AC Size Ratio input. This allows you to consider different system sizing strategies and operational effects such as clipping. The default value is 1.1." It's unclear if this is the same as the 1.2 value hard-coded in the BEopt PV model.

comment:2 Changed 5 years ago by cchriste

  • Resolution set to fixed
  • Status set to closed
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