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Which model simulates better the performance of photovoltaic panels? The Sandia or one-diode model?

asked 2016-10-24 10:09:38 -0500

Annelore's avatar

updated 2016-10-24 14:31:40 -0500

Im studying the performance of photovoltaic panels and I need to know which model represents better the real performance of photovoltaic panels and why. I have read the Input Output Reference and the Engineering Reference but I need to know wich is better to simulate a Net Zero Energy Building.

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answered 2016-10-25 05:21:31 -0500

TL;DR: in my opinion if you have Sandia data for the actual PV panel you plan on using, use that, otherwise use the One-Diode model. Or phrased another way, maybe try to pick a module for which there is readily available Sandia data.

The two models are inherently different, not saying that one is good and the other is bad:

  • The equivalent one-diode model implemented in EnergyPlus is sometimes referred to as the TRNSYS model since it was first integrated in TRNSYS in the early 90s. It's a four-parameter model (see caveat below...), for which you supply catalog data, the model then generates I-V curves from catalog data, and assumes that the I-V curve is slope of the IV curve is zero at the short-circuit condition, which the engineering reference guide qualifies as a "reasonable approximation for crystalline modules".

Pros: can be used with any module given appropriate catalog data.

Cons: It's an approximation: the I-V curve is generated from an equation with 4-parameter. is it really accurate other than for crystalline modules?

  • The Sandia Model "consists series of empirical relationships with coefficients that are derived from actual testing"

Pros: Based on actual testing, so more accurate for a specific panel

Cons: can only be used for panels for which actual testing has been done.


Caveat about the one-diode model:

Is the one-diode model as 4P (= TRNSYS model) or a 5P (De Soto, 2004) model? Is the engineering reference guide outdated?

We've discussed this on Unmet Hours in the past when I was wondering whether you can use CEC data for the 4P model: Using the CEC Performance Database data for Solar PV in E+

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Just found a github issue I opened a year ago about clarifying the one-diode documentation here

Julien Marrec's avatar Julien Marrec  ( 2016-10-25 05:23:16 -0500 )edit

I agree that Sandia is considered the most representative of real world performance. I seem to recall there may be some ways of generating input from more detailed models rather than always requiring physical testing. The one-diode has shown numerical problems in the solver and tricky sensitivity to input sets. The robust and easy PhotovoltaicPerformance:Simple is a useful fallback, just lop off 2% efficiency or so to be conservative and catch balance of systems losses.

Archmage's avatar Archmage  ( 2016-10-25 10:08:35 -0500 )edit

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Asked: 2016-10-24 10:09:38 -0500

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Last updated: Oct 25 '16